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Skeletal Series: The Basic Human Osteology Glossary

19 Dec

Introducing the Human Osteology Glossary

It is important for the budding human osteology student that they understand and correctly apply the basic terms used in the discipline to help identify and describe the skeletal anatomy under study.  Since human osteologists study the skeletal remains of anatomically modern humans (Homo sapiens) the terminology used, specifically the anatomical terminology, has to be precise and correct as befitting the medical use of such terms.

Human osteology remains the foundation on which the disciplines of forensic anthropology and bioarchaeology are built upon, although it is noted that the disciplines can be misleading across international divides.  For example, in the United Kingdom bioarchaeology is still used to refer to the study of both human and non-human skeleton remains from archaeological sites, whilst bioarchaeology in the United States normally refers to human remains only.  It should also be noted here that the other related disciplines, such as palaeoanthropology and biological anthropology, study not just the modern human skeleton but also the skeletal and fossilized remains of extant (genera such as Pan, Pongo and Gorilla) and extinct hominins.  Nevertheless the terminology remains the same when describing the skeletal anatomy of both human and non-human individuals.

Glossary Arrangement

This short glossary is intended to provide a basic introduction to the terminology used in the disciplines that utilizes human osteology as a core focus for the research undertaken.  The terminology documented here also includes a brief description of the word and, where possible, an example of its use.  Primarily the glossary acts as a reference post in order to be used in conjunction with the Skeletal Series posts on this site, which help outline and introduce each skeletal element of the human body section by section and as appropriate.  However please note that the glossary is also arranged in a manner in which it befits the student who needs to quickly scan the list in order to find a specific and relevant word.

Therefore the glossary is arranged in a thematic presentation as follows:

1. Discipline Definitions
2. The Human Body:
– a) Macro
– b) Micro
– c) Growth
– d) Disease and Trauma
3. Anatomical Foundations:
– a) Anatomical Planes of Reference
– b) Directional Terminology
– c) Movement Terminology
4. Postmortem Skeletal Change
– a) Postmortem Skeletal Change

The glossary ends with an introduction to the terminology used to describe the postmortem aspects of body deposition.  This is because it is an important aspect and consideration of any skeletal analysis undertaken.  The terminology used in this section leads away from the strictly anatomical terminology of the sections above it and introduces some terms that are used in archaeology and associated disciplines.

Reference Note

Please note that the bibliography provided indicates a number of important texts from which this glossary was compiled.  The key text books highlighted also introduce the study of the human skeleton, from a number of different perspectives, including the gross anatomical, bioarchaeological and human evolutionary perspectives.  Find a copy of the books at your library or order a copy and become engrossed in the beauty of the bones and the evidence of life histories that they can hold.

The Glossary:

1) – Discipline Definitions

Bioanthropology:  A scientific discipline concerned with the biological and behavioral aspects of human beings, their related non-human primates, such as gorillas and chimpanzees, and their extinct hominin ancestors.  (Related Physical Anthropology).

Bioarchaeology:  The study of human and non-human skeletal remains from archaeological sites.  In the United States of America this term is used solely for the study of human skeletal remains from archaeological sites.

Forensic Anthropology:  An applied anthropological approach dealing with human remains in legal contexts.  Forensic anthropologists often work with coroners and others, such as disaster victim identification teams, in analysing and identifying human remains (both soft and hard tissues) from a variety of contexts including but not limited ID’ing remains from natural disasters, police contexts, war zones, genocides, human rights violations, etc.

Human Osteology:  The study of human skeletal material.  Focuses on the scientific interpretation of skeletal remains from archaeological sites, including the study of the skeletal anatomy, bone physiology, and the growth and development of the skeleton itself.   

Palaeoanthropology:  The interdisciplinary study of earlier hominins.  This includes the study of their chronology, physical structure and skeletal anatomy, archaeological remains, geographic spans, etc. (Jurmain et al. 2011).

Physical Anthropology:  Concerned with the biological skeletal remains of both humans and extant and extinct hominins, anatomy, and evidence of behaviour.  The discipline is often considered congruent with the term bioanthropology, or biological anthropology.  (Related Bioanthropology).

2) a. – The Human Body: Macro

Appendicular Skeleton:  The skeletal bones of the limbs.  Includes the shoulder and pelvic girdles, however it does not include the sacrum.  Skeleton SK423 largely consisted of the non-fragmented disarticulated appendicular elements.

Axial Skeleton:  The skeletal elements of the trunk of the body.  Includes the ribs, vertebrae and sternum.  The body of SK424 was particularly fragmented in-situ, with little sign of excavation or post-excavation damage evidenced on the axial skeleton suggesting fragmentation post-burial.

Cortical (Compact) Bone:  The solid and dense bone found in the bone shafts and on the external surfaces of bone itself.  The cortical bone of the mid-shaft of the right humerus of the tennis player displayed increased thickening.  This is, in this individuals case whose physical history is known, due to the predominance of the right arm during intense and long-term use in physical exercise (see Wolff’s Law). 

Dentin (Dentine):  Calcified but slightly resilient dental connective tissue.  In human growth primary dentin appears during growth whereas secondary dentin forms after the root formation of the tooth is complete (White & Folkens 2005: 421).

Diaphysis:  The shaft portion of a long bone.  The diaphysis of the femur is one of the longest shafts found in the human skeleton, as the femur is the longest bone.

Dry Bone:  Refers to archaeological bone where no soft, or wet, tissue survives, hence the bone is dry.  It should be noted that, when subject to x-rays for investigation, archaeological dry bone radiological images are improved due to a lack of soft tissues obscuring the bone condition.

Elements (Skeletal):  Used to refer to each individual bone.  The human adult body has, on average, 206 individual skeletal elements.

Enamel:  Enamel is an extremely hard brittle material which covers the crown of a tooth.

Endosteum:  A largely cellular membrane that lines the inner surface of bones which is ill-defined (White & Folkens 2005: 421).

Epiphysis:  The epiphysis refers to the often proximal and distal ‘caps’ of long bones that develop from a secondary ossification centre.  The epiphysis of the long bones can, when used in conjunction with other skeletal markers of aging, particularly dentition, provide a highly accurate  age-at-death in non-adult human skeletal remains.

Medullary Cavity:  The cavity found inside the shaft of a long bone.  The medullary cavity of the femur is the site of the longest medullary cavity found in the human body.  The medullary cavity is the location where red and yellow bone marrow is stored and where the red and white blood cells are produced. 

Metaphyses:  The metaphyses refer to the expanded and flared ends of the shaft (or diaphysis) of long bones.  Both the femoral and humeral diaphyses display flared distal metaphyses which are indicative of their anatomical positioning.

Morphology:  The form and structure of an object.  The morphology of the femora is dictated by a variety of factors, not least the size, age, sex and weight of the individual.

Musculoskeletal System:  The musculoskeletal system provides the bony framework of the body in which the muscles attach onto and are able to leverage bones to induce movement.  The musculoskeletal system is responsible for a number of core bodily functions, including blood production and nourishment, alongside providing a stable and safe environment for vital organs.

Osteology:  The scientific study of bone.  Bones form the basis of the skeletal system of vertebrate animals, including humans.  In the United States of America bioarchaeology refers to the study of human bones within an archaeological context.

Periosteum:  The thin dense vascular connective tissue that covers the outer surfaces of bone during life, except on areas of articulation.  The periosteum tissue plays an important part in the maintenance of healthy bone, helping to also provide the body with blood via the bone marrow and associated vessels.  The periosteum provides an important area of osteogensis following a bone fracture.

Postcranial Skeleton:  All bones but the mandible and cranium.  The postcranial skeleton of SK543 was exceptionally well-preserved within the grave context but due to grave cutting the cranium and mandible were completely disturbed and not present within the context recorded.

Trabecular (Spongy) Bone:  Refers to the honeycomb like structure of bone found within the cavity of bones themselves.

2) b. – The Human Body: Micro

Cartilage:  Cartilage is a flexible connective tissue which consists of cells embedded in a matrix.  In the human skeletal system cartilage is found between joints, such as the knee and in forms such as the intervertebral disk in the spine and in the ribcage.  There are three types of cartilage: hyaline, fibrocartilage and elastic cartilage in the human skeletal system, although 28 different types of cartilage have now been identified in the human body as a whole (Gosling et al. 2008:9).

Collagen:  Collagen is a fibrous structural tissue in the skeleton which constitutes up to 90% of bone’s organic content (White & Folkens 2005: 42).

Haversian Canal (Secondary Osteons):  Microscopic canals found in compact, or cortical, bone that contain blood, nerve and lymph vessels, alongside marrow.

Hydroxyapatite:  A dense, inorganic, mineral matrix which helps form the second component of bone.  Together with collagen hydroxyapatite gives bone the unique ability to withstand and respond to physical stresses.

Lamellar (Mature) Bone:  Bone in which the ‘microscopic structure is characterized by collagen fibres arranged in layers or sheets around Haversian canals’ (White & Folkens 2005: 423).  Lamellar bone is mechanically strong.  Related woven (immature) bone.

Osteoblast:  Osteoblasts are the ‘bone-forming cells which are responsible for synthesizing and depositing bone material’ (White & Folkens 2005: 424).

Osteoclast:  Osteoclasts are the cells responsible for the resorption of bone tissue.

Osteocyte:  Osteocytes are the living bone cell which is developed from an osteoblast (White & Folkens 2005: 424).

Osteon:  The osteon is a Haversian system, ‘a structural unit of compact bone composed of a central vascular (Haversian) canal and the concentric lamellae surrounding it; a Primary Osteon is composed of a vascular canal without a cement line, whereas the cement line and lamellar bone organized around the central canal characterize a Secondary Osteon‘ (White & Folkens 2005: 424).

Remodeling:  Remodeling is the cyclical process of bone resorption and bone deposition at one site.  The human skeleton continually remodels itself throughout life, and after full growth has been achieved towards the end of puberty.  Further to this bone is a tissue that responds to physical stress and remodels as appropriate. 

Woven (Immature) Bone:  characterized by the haphazard organisation of collagen fibres.  Primarily laid down following a fracture and later replaced by lamellar bone.  Woven bone is mechanically weak.  Related lamellar (mature) bone.

2) c. – The Human Body: Growth

Appositional Growth:  The process by which old bone that lines the medullary cavity is reabsorbed and new bone tissue is grown beneath the periosteum, which increases the bone diameter.

Endochondral Ossification:  One of two main processes of bone development in which cartilage precursors (called cartilage models) are gradually replaced by bone tissue (White & Folkens 2005: 421).

Epiphyseal (Growth) Plate:  The hyaline cartilage plate found at the metaphyses of the long bones during growth of the individual (i.e. non-adults), where bone growth is focused until full growth cycle has been completed.

Idiosyncratic:  Referring to the individual.  The normal morphology of the human skeleton, and its individual elements, is influenced by three main factors of variation: biological sex (sexual dimorphism), ontogenetic (age), and idiosyncratic (individual) factors.

Intramembranous Ossification:  One of two main processes of ‘bone development in which bones ossify by apposition on tissue within an embryonic connective tissue membrane’ (White & Folkens 2005: 422).

Ontogeny:  The growth, or development, of an individual.  Ontogeny can be a major factor in the morphological presentation of the human skeleton.

Osteogenesis:  The formation and development of bone.  Embryologically the development of bone ossification occurs during two main processes: intramembranous and endochondral ossification.

Wolff’s Law:  Theory developed by German anatomist and surgeon Julius Wolff (1836-1902) which stated that human and non-human bone responded to the loads, or stresses, under to which it is placed and remodels appropriately within a healthy individual.

Sexual Dimorphism:  The differences between males and females.  The human skeleton has, compared to some animal species, discrete differences in sexual dimorphism; however there are distinct functional differences in the morphology of certain elements which can be used to determine biological sex of the individual post-puberty.

2) d. – The Human Body: Disease and Trauma

Atrophy:  The wastage of an organ or body tissue due to non-use.  Atrophy can be an outcome of disease processes in which the nerves are damaged, leading to the extended, or permanent, non-use of a limb which can lead to muscle wastage and bone resorption.

Blastic Lesion: Expansive bone lesion in which bone is abnormally expanded upon as part of part of a disease process.  The opposite of lytic lesion.

Calculus: Tartar; a deposit of calcified dental plaque on the surface of teeth.  The calculus found on the teeth of the archaeological skeleton can contain a wealth of information on the diet and extramasticatory activities of the individual.

Callus:  The hard tissue which is formed in the osteogenic (bone cell producing) layer of the periosteum as a fracture repair tissue.  This tissue is normally replaced by woven bone, which is in turn replaced by lamellar (or mature) bone as the bone continues to remodel during the healing process.

Caries:  Caries are ‘a disease characterized by the ‘progressive decalcification of enamel or dentine; the hole or cavity left by such decay’ (White & Folkens 2005: 420).  The extensive caries present on the 2nd right mandibular molar of Sk344 nearly obliterates the occlusal (chewing) surface of the tooth.

Compound Fracture:  A fracture in which the broken ends of the bone perforate the skin.  A compound fracture can be more damaging psychologically to the individual, due to the sight of the fracture itself and soft tissue damage to the skin and muscle.  Compound fractures also lead to an increased risk of fat embolism (or clots) entering the circulatory system via marrow leakage, which can be potentially fatal.

Dysplasia:  The abnormal development of bone tissue.  The bone lesions of fibrous dysplasia display as opaque and translucent patches compared to normal healthy bone on X-ray radiographic images.

Eburnation: Presents as polished bone on surface joints where subchondral bone has been exposed and worn.  Osteoarthritis often presents at the hip and knee joints where eburnation is present on the proximal femoral head and distal femoral condyle surfaces, alongside the adjacent tibia and iliac joint surfaces.

Hyperostosis:  An abnormal growth of the bone tissue.  Paget’s disease of bone is partly characterized by the hyperostosis of the cranial plates, with particularly dense parietal and frontal bones.

Hyperplasia:  An excessive growth of bone, or other, tissues.

Hypertrothy:  An increase in the volume of a tissue or organ.

Hypoplasia:  An insufficient growth of bone or other tissue.  Harris lines are dense transverse lines found in the shafts of long bones, which are indicative of arrested growth periods, as non-specific stress events, in the life of the individual.  Harris lines can often only be identified via X-ray radiography or through visual inspection of internal bone structure.

Lytic Lesion:  Destructive bone lesion as part of a disease process.  The opposite of a blastic lesion.  Syphilitic lytic bone lesions often pit and scar the frontal, parietal and associated facial bones of the skull.

Osteoarthritis:  Osteoarthritis is the most common form of arthritis, which is characterized by the destruction of the articular cartilage in a joint.  This often leads to eburnation on the bone surface.  Bony lipping and spur formation often also occur adjacent to the joint.  This is also commonly called Degenerative Joint Disease (DJD) (White & Folkens 2005: 424).

Osteophytes:  Typically small abnormal outgrowths of bone which are found at the articular surface of the bone as a feature of osteoarthritis.  Extensive osteophytic lipping was noted on the anterior portion of the vertebrae bodies of T2-L3 which, along with the evidence of eburnation, bony lipping and spurs presenting bilaterally on the femora and tibiae, present as evidence of osteoarthritis in SK469.

Pathognomonic:  A pathological feature that is characteristic for a particular disease as it is a marked intensification for a diagnostic sign or symptom.  A sequestrum (a piece of dead bone that has become separated from normal, or healthy, bone during necrosis) is normally considered a pathgonomic sign of osteomyelitis. 

Pathological Fracture:  A bone fracture that occurs due to the result of bones already being weakened by other pathological or metabolic conditions, such as osteoporosis (White & Folkens 2005: 424).

Palaeopathology:  The study of ancient disease and trauma processes in human skeletal (or mummified) remains from archaeological sites.  Includes the diagnosis of disease, where possible.  A palaeopathological analysis of the skeletal remains of individuals from the archaeological record is an important aspect of recording and contextualising health in the past.

Periodontitis:  Inflammation around the tissues of a tooth, which can involve the hard tissues of the mandibular and maxilla bone or the soft tissues themselves.  Extensive evidence of periodontitis on both the mandible and maxilla suggests a high level of chronic infection.

Periostitis: The inflammation of the periosteum which is caused by either trauma or infection, this can be either acute or chronic.  The anterior proximal third of the right tibia displayed extensive periostitis suggesting an a persistent, or long term, incidence of infection.

Radiograph:  Image produced on photographic film when exposed to x-rays passing through an object (White & Folkens 2005: 425).  The radiographic image of the femora produced evidence of Harris lines which were not visible on the visual inspection of the bones.

3) a. – Anatomical Planes of Reference

Anatomical Position (Standard):  This is defined as ‘standing with the feet together and pointing forward, looking forward, with none of the leg bones crossed from a viewer’s perspective and palms facing forward’ (White & Folkens 2005: 426).  The standard anatomical position is used when referring to the planes of reference, and for orientation and laying out of the skeletal remains of an individual for osteological examination, inventory, and/or analysis.

Coronal (frontal/Median):  The coronal plane is a vertical plane that divides the body into an equal forward and backward (or anterior and posterior) section.  The coronal plane is used along with the sagittal and transverse planes in order to describe the location of the body parts in relation to one another.

Frankfurt Horizontal:  A plane used to systematically view the skull which is defined by three osteometric points:  the right and left porion points (near the ear canal, or exterior auditory meatus) and left orbitale.

Oblique Plane:  A plane that is not parallel to the coronal, sagittal or transverse planes.  The fracture to the mid shaft of the left tibia and fibula was not a transverse or spiral break, it is an oblique fracture as evidenced by the angle of the break. 

Sagittal:  A vertical plane that divides the body into symmetrical right and left halves.

Transverse:  Situated or extending across a horizontal plane.  A transverse fracture was noted on the midshaft of the right femur.  The fracture was indicative of a great force having caused it, likely in a traumatic incident.

3) b. – Anatomical Directional Terminology

Superior:  Superior refers towards the head end of the human body, with the most superior point of the human body the parietal bone at the sagittal suture (White & Folkens 2005: 68).

Inferior:  Inferior refers towards the foot, or the heel, which is the calcaneus bone.  Generally this is towards the ground.  The tibia is inferior to the femur.

Anterior:  Towards the front of the body.  The sternum is anterior to the vertebral column.

Posterior:  Towards the back of the body.  The occipital bone is posterior to the frontal bone of the cranium.

Proximal:  Near the axial skeletonThe term is normally used for the limb bones, where for instance the proximal end of the femur is towards the os coxa.

Medial:  Towards the midline of the body.  The right side of the tongue is medial to the right side of the mandible.

Lateral:  The opposite of medial, away from the midline of the body.  In the standard anatomical position the left radius is lateral to the left ulna.

Distal:  furthest away from the axial skeleton; away from the body.  The distal aspect of the humerus articulates with the proximal head of the radius and the trochlear notch of the ulna.

Internal:  Inside.  The internal surface of the frontal bone has the frontal crest, which is located in the sagittal plane.

External: Outside.  The cranial vault is the external surface of the brain.

Endocranial:  The inner surface of the cranial vault.  The brain fills the endocranial cavity where it sits within a sack.

Ectocranial:  The outer surface of the cranial vault.  The frontal bosses (or eminences) are located on the ectocranial surface of the frontal bone.

Superficial:  Close to the surface of the body, i.e. towards the skin.  The bones of the cranium are superficial to the brain.

Deep:  Opposite of superficial, i.e. deep inside the body and far from the surface.  The lungs are deep to the ribs, but the heart is deep to the lungs.

Palmar:  Palm side of the hand.  The palm side of the hand is where the fingers bear fingerprints.

Plantar:  The plantar side of the foot is the sole.  The plantar side of the foot is in contact with the ground during normal ambulation.

Dorsal:  Either the top of the foot or the back of the hand.  The ‘dorsal surface often bears hair whilst the palmar or plantar surfaces do not’ (White & Folkens 2005: 69).

3) c. – Anatomical Movement Terminology

Abduction:  Abduction is a laterally directed movement in the coronal plane away from the sagittal, or median, plane.  It is the opposite of adduction.  Standing straight, with the palm of the left hand anterior, raise the left arm sideways until it is horizontal with the shoulder: this is the action of abducting the left arm.

Adduction:  Adduction is the medially directed movement in the coronal plane towards the sagittal, or median, plane.  It is the opposite of abductionStanding straight, with the palm of the right hand anterior, and the right arm raised sideways until it is horizontal with the shoulder, move the arm down towards the body.  This is adduction.

Circumduction:  Circumduction is a ‘circular movement created by the sequential combination of abduction, flexion, adduction, and extension’ (Schwartz 2007: 373).  The guitarist who performs the action of windmilling during playing is circumducting their plectrum holding limb.

Extension:  Extension is a movement in the sagittal plane around a transverse axis that separates two structures.  It is the opposite of flexionThe extension of the forearm involves movement at the elbow joint.

Flexion:  A bending movement in the saggital plane and around a transverse axis that draws two structures toward each other (Schwartz 2007: 374).  It is the opposite of extensionThe flexion of the forearm involves movement at the elbow joint.

Lateral Rotation:  The movement of a structure around its longitudinal axis which causes the anterior surface to face laterally.  It is the opposite of medial rotation.

Medial Rotation:  The movement of a structure around its longitudinal axis that causes the anterior surface to face medially.  It is the opposite of lateral rotation (Schwartz 2007: 376).

Opposition: The movement of the ‘thumb across the palm such that its “pad” contracts the “pad” of another digit; this movement involves abduction with flexion and medial rotation’ (Schwartz 2007: 377).

4) a. – Postmortem Skeletal Change

Antemortem:  Before the time of death.  The evidence for the active bone healing on both the distal radius and ulna diaphyses, with a clean fracture indicating use of a bladed instrumented, suggests that amputation of the right hand occurred antemortem. 

Bioturbation:  The reworking of soils and associated sediments by non-human agents, such as plants and animals.  Bioturbation can lead to the displacement of archaeological artefacts and structural features and displace deposited human skeletal bone.  Evidence of bioturbation in the cemetery was noted, as irregular tunnels were located across a number of different grave contexts suggesting the action of a burrowing or nesting mammal.  This led to the disarticulation of skeletal material within the grave contexts themselves which, on first investigation, may have led to an incorrect analysis of the sequence of events following the primary deposition of the body within the grave.

Commingled:  An assemblage of bone containing the remains of multiple individuals, which are often incomplete and heavily fragmented.  The commingled mass grave found at the Neolithic site of Talheim, in modern southern Germany, suggest that, along with the noted traumatic injuries prevalent on the individuals analysed, rapid and careless burial in a so-called ‘death pit’ took place by the individuals who carried out the massacre.  The site is a famous Linearbandkeramik (LBK) location which dates to around 5000 BC, or the Early European Neolithic.  Similar period mass burials include those at Herxheim, also in Germany, and Schletz-Asparn in nearby Austria.

Diagenesis:  The chemical, physical, and biological changes undergone by a bone through time.  This is a particularly important area of study as the conservation of bones must deal with bacteria and fungal infection of conserved bone if the skeletal material is to be preserved properly.  Analysis of the diagenesis of skeletal material can also inform the bioarchaeologist of the peri and postmortem burial conditions of the individual by comparing the environmental contexts that the bone had been introduced to.

Perimortem: At, or around, the time of death.  The decapitation of SK246 occurred perimortem as evidenced by the sharp bladed unhealed trauma to the associated body,  pedicles, lamina and spinal arches of the C3 and C4 vertebrae.

Postmortem: Refers to the period after the death of the individual.  It is likely that the body had been moved postmortem as indicated by position of the body in the bedroom and by the extensive markers on the skin, suggesting physical manipulation and accidental contusions.  Further to this the pooling of the blood within the first few hours postmortem was not indicative of where the body was located at the time of discovery.

Postmortem Modification:  Modifications, or alterations, that occur to the skeletal remains after the death of the individual.  No postmortem modification of the skeletal elements of SK543 was noted, however extensive evidence of bioturbation in the form of root action was noted on across the majority (> 80%) of the surface of the surviving skeletal elements recovered.

Taphonomy:  The study of processes that can affect the skeletal remains between the death of the individual and the curation, or analysis, of the individual.  There are a variety of natural and non-natural taphonomic processes that must be considered in the analysing of human skeletal material from archaeological, modern and forensic contexts.  This can include natural disturbances, such as bioturbation, or non-natural, such as purposeful secondary internment of the body or skeletal remains.

Note on the Terminology Used & Feedback

The terminology used above, and their definitions, are taken in part from the below sources.  Direct quotations are referenced to the source and page.  They, the sources in the bibliography, are a small handful of some of the exceptional books available which help to introduce the human skeletal system and the importance of being able to identify, study and analyse the bones in a scientific manner.  The human skeletal glossary present here is subject to revision, amendments and updates, so please do check back to see what has been included.  Finally, I heartily advise readers to leave a comment if revisions, or clarifications, are needed on any of the terms or definitions used in the glossary.

Bibliography & Further Reading

Gosling, J. A., Harris, P. F., Humpherson, J. R., Whitmore, I., Willan, P. L. T., Bentley, A. L., Davies, J. T. & Hargreaves, J. L. 2008. Human Anatomy: Colour Atlas and Texbook (5th Edition). London: Mosby Elsevier.

Jurmain, R., Kilgrore, L. & Trevathan, W. 2011. Essentials of Physical Anthropology. Belmont: Wadsworth.

Larsen, C. S. 1997. Bioarchaeology: Interpreting Behaviour from the Human Skeleton. Cambridge: Cambridge University Press.

Lewis, M. E. 2007. The Bioarchaeology of Children: Perspectives from Biological and Forensic Anthropology. Cambridge: Cambridge University Press.

Roberts, C. & Manchester, K. 2010. The Archaeology of Disease (3rd Edition). Stroud: The History Press.

Schwartz, J. H. 2007. Skeleton Keys: An Introduction Human Skeletal Morphology, Development, and Analysis (2nd Edition). New York: Oxford University Press.

White, T. D. & Folkens, P. A. 2005. The Human Bone Manual. London: Elsevier Academic Press.

Skeletal Series Part 12: Human Teeth

28 Oct
teeeeeethhh

Basic human permanent dentition. Click to enlarge.  Image credit: modified from here.

Teeth, as a part of the dentition, are a wonder of the natural world and come in a variety of forms and designs in vertebrate animals, with perhaps some of the most impressive examples include the tusks of elephants and walruses.  They are also the only part of the human skeletal system that can be observed naturally and the only part that interact directly with their environment via mastication (White & Folkens 2005: 127).

Although primarily used to break down foodstuffs during mastication, teeth can also be used as tools for a variety of extramasticatory functions such as the processing of animal skins and cord production (Larsen 1997: 262).  As the hardest of the biological material found in the body teeth survive particularly well in both the archaeological and fossil records, often surviving where bones do not.  Teeth are a goldmine of information for the human osteologist and forensic anthropologist alike as they can be indicative of the sex, age, diet and geographic origin of the individual that they belong to (Koff 2004, Larsen 1997, Lewis 2009, White & Folkens 2005).

This entry will introduce the basic anatomy of the human dental arcade, deciduous and permanent dentition and the various tooth classes, alongside a quick discussion of the action of mastication itself.  But first, as always in this series, we’ll take a look at how teeth can be found during the excavation of archaeological sites.  This post marks the final Skeletal Series post to deal explicitly with individual elements of the human skeletal system.  The next few posts in the Skeletal Series will be aimed at detailing the methods used in aging and sexing elements in the adult and non-adult skeleton (and the success rates of the various methods), followed by posts introducing the pathological conditions that can be present on human skeletal remains.

Excavation

The 32 permanent human teeth, located in the upper arcade (maxilla) and lower arcade (mandible) of the jaws, each holding 16 teeth, are resilient to chemical and physical degradation.  Furthermore tooth crown morphology (the surface that consists of enamel) can only be changed by attrition (tooth wear), breakage, or demineralization once the crown of a tooth has erupted through the gum line (White & Folkens 2005: 127).  As such teeth are often found at locations where human remains are suspected to be buried or otherwise excavated.  Care must be taken around the fragile bones of the spanchnocranium (i.e. the facial area of the skull), defined as necessary, and, if needed due to fragility, the area may have to be lifted with natural material still adhered to the bone to be more carefully micro-excavated in the lab (Brothwell 1981: 3).

Circled in red, the teeth are located in the upper (maxilla) and lower (mandible) jaws. This individual, dating to the medieval period in eastern Germany, highlights a common occurrence in supine burials where the mandible often ‘falls’ forward as the muscles, ligaments and tendons decompose. Always be careful when excavating suspected burial features as both bone and tooth can be chipped by trowels or other metallic excavation implements. Photograph taken by author.

Loose dentition may be found around the skull itself as teeth can be loosened naturally postmortem as natural ligaments decompose.  Sieving around the location of the skull may prove useful in finding loose teeth and also the smaller bones of the skulls (such as the ear ossicles).  In the excavation of non-adult remains, or of suspected females with fetal remains in-situ, great care should be taken in recording and the excavating of the skull, torso and pelvis.  As mentioned below teeth form from the crown down, as such deciduous or permanent teeth during growth may be loose in exposed crypts in the mandible or maxilla (Brickley & McKinley 2004).  Furthermore due to the small size and colour of the 20 deciduous teeth, especially the crowns during the formation and growth of the teeth, may be mistaken for pieces of dirt or rocks.

Tooth Anatomy & Terminology

The basic anatomy of teeth can be found in the diagram below, but it is worth listing the anatomical features of a typical tooth here.  The chewing surface of the tooth is called the occlusal surface and it is here that the crown of the tooth can be found.  The crown of a tooth is made of enamel, an extremely hard and brittle mixture of minerals (around 95-96% hydroxyapatite).  The enamel is formed in the gum and once fully formed contains little organic material.  The demineralization of teeth can repair initial damage, however this is limited in nature.  Dentin (sometimes termed dentine) is the tissue that forms the core of the tooth itself.  It is supported by a vascular system in the pulp of the tooth.  Dentin can only repair itself on the inner surface (the walls of the pulp cavity), but dentin is a softer material than enamel and once exposed by occlusal wear it erodes faster than enamel.  The pulp chamber, in the centre of the diagram below, is the largest part of the pulp cavity at the crown end of the tooth.  The pulp itself is the soft tissue inside the pulp chamber, which includes the usual trio bundle of vein, artery and nerves (V.A.N.).  The root of the tooth is the part that anchors it into the dental alveolus tissue (sockets) of the jaw (either the maxilla or mandible).

Toothanatomy2

The basic anatomy of a tooth (in this case a molar), outlining the three main layers present in all human teeth. Image credit: Kidport.

Cementum is the bone type tissue that covers the external surface of the roots of teeth.  The apex, or apical foramen, is the opening at the end of each root, which allows for the nerve fibers and vessels up the root canal into the pulp chamber.  Heading back up to the occlusal surface of the tooth we encounter cusps of the crown, each of which have different individual names depending on their position.  Upper teeth end with the prefix -cone whereas lower teeth end with the prefix -conid (see details here).  Finally we have fissures, which are clefts between the occlusal surfaces between cusps.  Fissures help divide the cusps into patterns and are helpful to know to help identity individual teeth (specifically the molars).  Above information taken from White & Folkens (2005: 130-131).

As previously highlighted there are some directional terms that are specific to the dentition, but it is pertinent to repeat some of the key aspects here for clarification as tooth orientation is important –

Apical: towards the root.
Buccal: towards the cheek (the buccinator muscle- the terminator of the muscle world!), used in realtion to posterior teeth (premolars and molars) only.
Cervical: towards the base of the crown or neck of the tooth (often called the cementoenamel junction).
Distal (direction): away from the midline of the mouth, opposite of mesial.
Incisal: towards the cutting edge of the anterior teeth.
Interproximal: between adjacent teeth, also useful to know and be able to identify are interproximal contact facets (IPCFs) which can indicate anatomical location of  tooth.
Labial: surface towards the lips, anterior teeth (canines and incisors) only.
Lingual: of the tooth crown towards the tongue.
Mesial (direction): towards the midline, closest to the point where the central incisors contact each other.
Occlusal: towards the chewing surface (crown) of the tooth.

teethdirect

Tooth anatomical direction terminology and legend of tooth position, above is the maxillary dental arcade. Typically the uppercase and lowercase numbers refer to maxilla and mandible positions respectively, and often include a L or R for left or right hand side for quadrant location. In deciduous dentition lower case letters are used, in permanent dentition capitalization is used. Premolars are often 3rd (1st premolar) and 4th (2nd premolar) after palaeontological standards. Check out Brickley & McKinley (2004) below for BABAO recording standards. Image credit: Dr Lorraine Heidecker @ Redwoods.edu.

Above information taken from White & Folkens (2005: 128) and here.

A different method for recording the presence/absence and state of the individual teeth from archaeological skeletal populations is proposed by the British Association of Biological Anthropology and Osteoarchaeology (BABAO) as mentioned above.  In this method, proposed by Connell (2004: 8) the deciduous and permanent dentition are given a separate letter or number:

toothrecording

The BABAO 2004 guidelines for compiling a dental inventory for a skeleton. It should be noted that if compiling a large inventory for a population it is best to individually number and identify each tooth after the Buikstra & Ubelaker 1994 standards (but see also Bone Broke). Click to enlarge. Image credit: Connell (2004: 8).

Deciduous & Permanent Teeth

Humans have only two sets of teeth during their lifetimes.  The first set, known as the deciduous (primary or milk) teeth, are the first to form, erupt and function during the early years of life (White & Folkens 2005: 128).  The primary dentition consists of central incisor, lateral incisor, canine, first molar and second molar in each jaw quadrant, making a total of 20 individual deciduous teeth in all.

These are systematically lost and replaced by the permanent, or secondary, dentition throughout childhood, adolescence and early adulthood.  As noted above these include a central incisor, lateral incisor, canine, two premolars, and three molars in each jaw quadrant making a total of 32 individual permanent teeth in all.

The sequencing of the pattern of tooth eruption plays a vital clue in estimating the age of the individual, whilst tooth attrition (wear) is used in estimating individual age after the permanent dentition have fully erupted (White & Folkens 2005: 346).  The loss of a tooth, or teeth, antemortem (before death) can lead to alveolar resorption over the empty tooth socket.  Individuals who have no teeth left (often elderly individuals or individuals suffering periodontal disease) are termed edentulous.  This can lead to problems pronouncing words, the cheeks sagging inwards and problems chewing or grinding food (Mays 1999).  Perhaps the most famous example of this is one of the Dmanisi hominin fossils (crania D3444 and associated mandible D3900) whose crania lacked any teeth whatsoever and showed alveolar bone resorption of both the mandibular and maxillary arches.  However it is unknown if this is evidence of conspecific care, or just of survival, is not known (Hawks 2005).

teeth decid

The human deciduous dentition, notice the absence of any premolars and lack of third molar. The total number of deciduous teeth is 20. Not to scale. Image credit: identalhub.

Deciduous tooth formation begins only 14-16 weeks after conception.  White & Folkens (2005: 364) note that there are four distinct periods of emergence of the human dentition: 1) most deciduous teeth emerge and erupt during the 2nd/3rd year of life, 2) the two permanent incisors and first permanent molar usually emerge around 6-8 years old, 3) most permanent canines, premolars, and second molars emerges between 10-12 years old and finally 4) the 3rd molar emerges around 17/18 years old – although this can vary.  Note also that there are some differences between the sexes and between populations (Larsen 1997, Lewis 2009, Mays 1999).  Trauma, pathological conditions and diseases can also influence tooth development and eruption rates, often delaying the eruption of the permanent dentition and sometimes leaving visible deformities in the teeth themselves, such as linear enamel hypoplasia (sign of stress) or mulberry molars (specific sign of disease) (Lewis 2009: 41).

teeth perman

The human permanent dentition highlighting the 32 individual present. Notice the crown shape and sizes indicating different functions. Not to scale. Image credit: identalhub.

The basic differences between the deciduous and permanent dentition are as follows:

Deciduous…………………….Permanent

1. No premolars.                          2 premolars.

2. Smaller teeth, each              Larger teeth apart from premolars
tooth is smaller than                    which replace deciduous molars.
successor.

3. Cusps pointed &                  Cusps are blunt, crowns not bulbous,
crowns bulbous.                            contact areas broader.

4. Enamel less translucent, Enamel is more translucent, blueish white.
teeth appear whiter.

5. Enamel ends abruptly at    Enamel ends gradually,
the neck.                                             1st molars have no bulge at cervical margin.

6. Occlusally the Bucco-         Buccal and lingual surfaces do not converge,
lingual diameter                              therefore wider.
of molars is narrower.

7. Roots shorter and more    Roots longer and stronger, multi-rooted
delicate, separate close              teeth trunk present and roots
to crown, but are longer             do not diverge near crown.
compared to crown size.

8. Dentin is less thick.               Dentin is thicker.

9. Enamel more permeable        Enamel less permeable, more calcified,
less calcified, more                    relatively less attrition.
attrition.

Above information modified from White & Folkens 2005 and here.

Tooth Class

Teeth in humans are classed into 4 separate classes of tooth based on function and position.  The classes include incisors, canines, premolars and molars, each aiding the other during the mastication of food.

teeth jawline

The human permanent dentition. Notice the larger size of the maxilla (upper) crowns compared to the mandible (lower) crowns and the differences between the roots of the same class of tooth. The first molar is the largest of the molar and the first to erupt. This can tooth can often have evidence of attrition on its cusps and crown when the 2nd and 3rd molars lack abrasion due to the 1st’s early eruption. Not to scale. Image credit: Biologycs 2012.

Maxilla Teeth:

Incisors (general: crowns flat and blade-like, outline of dentine occlusal patch is often rectangular or square if exposed by wear)

The upper incisor crowns are broad (or mesiodistally elongated) relative to their height, and have more lingual relief.  The central incisor crown is larger and more symmetrical than the lateral incisor crown but the roots are shorter and stouter to crown size than to the lateral incisor roots (White & Folkens 2005: 142).

Canines (general: crowns are conical and tusklike, canine roots longer than other roots in the same dentition, can be confused for incisors)

Upper canines are broad relative to their height and have more lingual relief, with apical occlusal wear that is largely lingual (towards the tongue) (White & Folkens 2005: 139).

Premolars (general: crowns are round, shorter than canine crowns and smaller than molar crowns, generally only have two cusps, usually single rooted but can be confused for canines but note shorter crown height)

The upper premolar crowns have cusps of nearly equal size and the crowns are more oval in occlusal outline.  Further to this the crowns of upper premolars also have strong occlusal grooves that orient mesiodistally between the major cusps, this is a key identifier for maxilla premolars (White & Folkens 2005: 140).

Molars (general: crowns larger, squarer, bear more cusps than any other tooth class, have multiple roots, 3rd molars sometimes mistaken for premolars)

Generally peaking the maxilla molars go from largest to smallest (1st molar to 3rd molar) in size and morphology.  The crowns generally have 4 cusps.  The 1st molar has three roots (two buccal and one lingual, which when seen from the buccal position the lingual root comes into view in the middle of the two buccal roots).  The occlusal surface is described as a rhomboid in shape with 4 distinctive cusps.  The 2nd molar has three roots but the two buccal roots are nearly parallel with each other, and is described as heart shape in the occlusal view.  The 3rd molar has three roots present but the two buccal roots are often fused, and the outline of the occlusal surface is also described as a heart shape.  The 3rd molar also shows greater developmental variation than either the 1st or 3rd molars, and are often the tooth that is congenitally missing.  All roots of the molars angle distally with respect to the major crown axes (White & Folkens 2005: 152).

Mandibular Teeth:

Incisors

Lower incisor crowns are narrow compared to their height and have comparatively little lingual topography, further to this the roots are usually more mesiodistally compressed in cross-section (White & Folkens 2005: 139).  The lower central incisor crowns are slightly smaller than the lower lateral crowns, with shorter roots relative to the crown and absolutely than lateral incisors (White & Folkens 2005: 142).

Canines

Lower canines have comparatively little lingual relief compared to the upper canines, and the apical occlusal wear is mostly labial.  The lower canines are also narrow relative to their height (White & Folkens 2005: 139).

Premolars

Lower premolar crowns are more circular in occlusal outline than upper premolars, and have comparatively weak median line grooves.  In lower premolars the long axes of the roots are angled distally relative to the vertical axis of the crown.  When IPCFs are present they are mesial and distal in location (White & Folkens 2005: 150).

Molars

Generally speaking the mandibular molars go from largest (1st molar) to smallest (3rd molar) in size and morphology, same as the maxilla molars.  The 1st mandibular molar is very recognizable as it has the largest crown with 5 cusps in the distinctive Y-5 cusp pattern and a pentagonal occlusal surface.  The two roots of the tooth tend to be long, separate and divergent.  The 3rd molar is smaller than the 1st or 2nd and have more irregular cusps and lack distal IPCFs, it also has two short and poorly developed roots that curve distally.  The occlusal surface is often described as crenelated and ovoid in shape.  The 2nd molar crown is an intermediate of the 1st and 3rd crowns (with 4 cusps) and roots (which have a distal inclination) in morphological terms, but has a distinctive +4 pattern of the occlusal surface.  All roots of the molars angle distally with respect to the major crown axes.

Graphic of the mandibular right quadrant highlighting a few of the specific dental anatomy terms from the above section. Image credit: modified from Gray’s Anatomy here.

Information for this section taken from White & Folkens 2005: 133-152 and here.

For tooth identification there are four questions to bear in mind:

A) To which category (or class) does the tooth belong?
B) Is the tooth permanent or deciduous?
C) Is the tooth an upper or a lower?
D) Where in the arch is the tooth located?

Although I’ve hinted at some of the answers above, those questions are a whole other post!  But do investigate the Human Bone Manual by White and Folkens (2005) for further information and/or Brothwell (1981) and Mays (1999).

Note

This post will be updated to include the muscles of mastication.

Further Information

  • Over at Bone Broke Jess Beck has a number of detailed posts focusing on teeth, with a few entries describing the anatomy of the various classes of teeth in detail (expect future posts though!).  Particularly useful is the Identifying Human Teeth: Human Dentition Cheat Sheet post which can handily be downloaded as a PDF!
  • Check out this handy sheet for anatomical and direction terminology for teeth.
  • The University of Illinois at Chicago have a wonderfully helpful molar identification sheet available here.
  • Can teeth heal themselves? I wish!  Only a bit by demineralization, learn more here.
  • Over at What Missing Link? James R Lumbard has a fantastic post on how the muscles work, which includes a case study on the musculature of the jaw.
  • An in-depth 13-minute dissection video of the muscles of mastication can be found here.  Please be aware that this is a real human dissection.

Bibliography

Brickley, M. & McKinley, J. I. (eds.). 2004. Guidance to the Standards for Recording Human Skeletal Remains. BABAO & Reading: IFA Paper No. 7. (Open Access).

Brothwell, D. R. 1981. Digging Up Bones: The Excavation, Treatment and Study of Human Skeletal Remains. Ithica: Cornell University Press. (Open Access).

Connell, B. 2004. Compiling a Dental Inventory. In Brickley, M. & McKinley, J. I. (eds.) Guidance to the Standards for Recording Human Skeletal Remains. BABAO & Reading: IFA Paper No.7: 8. (Open Access).

Gosling, J. A., Harris, P. F., Humpherson, J. R., Whitmore I.,& Willan P. L. T. 2008. Human Anatomy Color Atlas and Text Book. Philadelphia: Mosby Elsevier.

Hawks, J. 2005. Caring for the Edentulous. John Hawks Weblog. Accessed 29th October 2014.

Koff, C. 2004. The Bone Woman: Among the Dead in Rwanda, Bosnia, Croatia and Kosovo. London: Atlantic Books.

Larsen, C. S. 1997. Bioarchaeology: Interpreting Behaviour from the Human Skeleton. Cambridge: Cambridge University Press.

Lewis, M. E. 2009. The Bioarchaeology of Children: Perspectives from Biological and Forensic Anthropology. Cambridge: Cambridge University Press.

Mays, S. 1999. The Archaeology of Human Bones. Glasgow: Bell & Bain Ltd.

White, T. & Folkens, P. 2005. The Human Bone Manual. London: Elsevier Academic Press.

Skeletal Series 11: The Human Foot

4 Sep

The human foot is as distinctive and as complex as the human hand (D’Août et al.  2010).  The foot, or Pes, forms the distal terminus of the leg.  It helps to perform the two basic important functions of shock absorption and propulsion during bipedal locomotion, both of which require a high degree of stability.  The foot bones are the serial homologs of the hand bones an each foot individually is comprised of 26  individual skeletal elements as opposed to the hand’s 27  individual skeletal elements, indicative of the differing evolutionary roles of both limbs with the digits undergoing reduction and modification in mammals (White & Folkens 2005: 225).

As White & Folkens (2005: 292) note, the ‘human foot has changed dramatically during its evolution from a grasping organ to a structure adapted to bipedal locomotion’, where ‘mobility, flexibility and grasping ability has been lost’.  As humans are bipedal walkers the feet must take the full weight of the body during locomotion and this is reflected in hard and soft tissue anatomy (D’Août et al. 2008, D’Août et al. 2010, Gosling et al. 2008, Jarmey 2003).  The diagram below demonstrates the robust and compact nature of the pes elements.

Foooooot

The human foot, highlighting the articulated individual skeletal elements in dorsal and lateral view. Note the arch of the foot, the size of the calcaneus and general robusticity of the bones in comparison to the hand bones (Image credit: WebMD 2013).

Excavation

The excavation of the human skeleton should, where possible, be conducted with patience and great care for the recovery of all skeletal material possible (Brothwell 1981).  The elements that make up the foot, a total of 26 individual bones altogether (see below), are sturdy and largely compact bones, although it is likely that there will not be complete recovery of the distal phalanges due to their smaller size.  In supine and crouched burials the foot bones are likely to survive, although care must be taken when excavating at an unknown burial depth (Larsen 1997).  In cremation remains of individuals from archaeological sites it is still possible for certain elements to be recognised and described, especially in the case of the compact tarsal bones (Mays 1999).  In crowded burial grounds where the body is laid out in a supine position (lying flat on the back), as n the photograph below, burials often intersect each other, cutting off the lower part of the legs (Mays 1999).  This is a common feature in crowded burial grounds, and care must be taken when excavating and assigning individual skeletal elements to specific individual skeleton’s (Brothwell 1981).

bones brodsworth 07pic3 - Copy

A photograph of a Medieval burial ground near Brodsworth, Yorkshire, UK, from the 2007 excavation. Note the orientation and sequential laying of supine burials, and how the lower portion of the legs have been covered or destroyed by other burials. Courtesy of the University of Hull and the Brodsworth project.

Basic Musculature and Skeletal Anatomy

There are 26 bones in the human foot which are grouped into 7 tarsals, 5 metatarsals and 14 phalanges, for a total of 33 joints, of which 20 are actively articulated (See image below for skeletal elements in articulation, and Gosling et al. 2008, Mays 1999, White & Folkens 2005, for further reference).  The main joints of the foot itself include the transverse tarsal joint and tarsometatarsal joint (see figure below).  The talocrural (ankle) joint, the articulation between the leg and the foot, forms an important part of the stability of the foot, one of the main differences behind the pes and the manus (the wrist is extremely movable and flexible in comparison to the ankle).  Unlike the hand the foot cannot grasp and is not capable of fine motor movement, however the adipose tissue and plantar fascia (or aponeurosis) is tightly packed underneath the heel (calcaneus bone) for shock absorption during locomotion (Gosling et al. 2008: 304).  The stability of the ankle joint is strengthened by the wedge shaped articulation of the talus and calcaneus bones and by the strong collateral ligaments helping to tightly pack the anatomy during movement (Gosling et al. 2008: 304-305).

footbones

The individual sections and bones of a right sided human foot, which includes the tarsals, metatarsals, and phalanges from proximal to distal (Image credit: Encyclopedia Britannia 2007).

It is important to note here the two main arches of the human foot, the transverse arches and the medial and lateral longitudinal arches.  The functional anatomy of the arches allows the foot to remain stable during the pressures and energy exertion of locomotion but also retain flexibility so that it can grip different surfaces whilst enhancing forward propulsion (Gosing et al. 2008: 309).  The transverse arch is located along the cuneiforms, the cuboid bone and all of the metatarsal bases, and simply forms a domed shaped which strengthens the foot during locomotion.  The medial longitudinal arch is the highest of the arches and runs along the instep of the foot, alongside the calcaneus, talus, navicular, and cuneiform bones and up to the first three metatarsals (Gosling et al. 2008: 309).  The lateral longitudinal arch is lower and flatter than the media arch and runs alongside the calcaneus, the cuboid, and the fourth and fifth metatarsals (Gosling et al. 2008: 2010).

The arches are supported in their skeletal frame by a complex arrangement of extrinsic and intrinsic muscles, ligaments and tendons.  The sole of the foot contains numerous intrinsic muscles which mimic the muscles found in the hand, which include digitorum (flexor/abductor) and lumbrical muscles, whilst the plantar view houses the inter-osseus planar muscles (Gosling et al. 2008: 284).  It is worth remembering that the majority of the larger muscles that articulate and move the foot are located in the leg itself (soleus, gastrocnemius, and the anterior/posterior tibial muscles).  Although I will not discuss the soft tissues further, I highly recommend the ‘Human Anatomy Colour Atlas and Textbook’ by Gosling et al. (2008) as a key reference source.  The book has a high number of quality dissection photographs and anatomical diagrams clearly highlighting the different muscle, ligament and tendon structures.

Skeletal Elements: Tarsals

The 7 tarsal bones of the foot help to form the longitudinal and transverse arches of the foot, which is often called the tarsus.  The talus articulates superiorly with the distal tibia and fibula, the calcaneus forms the heel of the foot and supports the talus (White & Folkens 2005: 291).  The navicular sites between the 3 cuneiforms and the head of the talus (White & Folkens 2005: 292).  The 3 cuneiforms and the cuboid act as a second row of tarsal bones and articulate with the proximal heads of the 5 metatarsals.

tarsals_labeled

Dorsal view of the tarsal elements and proximal metatarsals (Image credit: University of Cincinnati).

The Talus

The talus (astragalus in animals) is the 2nd largest tarsal and sits atop of the calcaneus, between the tibia and the fibula.  It is distinct in it’s saddle shape, with a head (that sides medially when viewed from above) and a body that forms the posterior portion of the bone.

The Calcaneus

The largest tarsal, forming the heel bone, the calcaneus is located inferior of the talus and supports the distal portion of the foot.  An intact calcaneus is extremely distinct, and can be sided by placing the ‘heel’ away from you and the articular surfaces superiorly, and the shelf (sustentaculum tali) should point the side it is from.

The Cuboid

The cuboid is located on the lateral side of the foot, between the calcaneus and the 4th and 5th metatarsals.  It is distinct in appearance because of its large size with a cuboidal body.  There is no articular surface on the lateral side of the bone, and the inferior surface has a pronounced cuboid tuberosity.

The Naviculuar

The navicular sits snugly between the talus and the cuneiform elements, and has a distinct concave proximal surface.  A tubercle points medially when viewed from the view of the talus.  It is similar in shape to the scaphoid carpal.

The Cuneiforms:

Medial

The medial cuneiform is the largest of the three cuneiforms, sitting between the navicular and base of the first metatarsal.  It is less of a wedge shape than the other two cuneiforms, and distinguished by it’s ‘kidney-shaped facet for the base of the first metatarsal’ (White & Folkens 2005: 298).

Intermediate

This cuneiform is the smallest of the cuneiforms and is located between navicular and the 2nd metatarsal base.  It articulates on either side with the lateral and medial cuneiforms.  The non-articular dorsal surface is key for siding, with a projecting surface points towards the side it comes from when the concave facet is pointed away from the holder (White & Folkens 2005: 298).

Lateral

Located at the centre of the foot, and intermediate in size between the intermediate and medial cuneiform, the lateral cuneiform sits at the base of the foot.  It articulates distally with the 2nd, 3rd and fourth metatarsal bases, proximally with the navicular, medially with the intermediate cuneiform and laterally the cuboid (White & Folkens 2005: 299).

Metatarsals

The 5 rays of the metatarsals are typically labelled as MT 1-5, with MT1 representing the hallux, or the big toe (as the thumb is named the pollex).  The metatarsals are all ‘tubular bones with rounded distal articular facets (heads) and more squarish proximal ends (bases)’ (White & Folkens 2005: 300).  They are more easily sided by the morphology of their bases.  It is important to note that each of the tarsals in the distal row (either of the 3 cuneiforms or the cuboid above) articulates with one or more of the metatarsal bases (White & Folkens 2005: 300).  The first metatarsal is the most massive and squat, whilst all non hallucial metatarsals articulate with each other.  The fifth metatarsal bears a distinctive blunt styloid process on it’s lateral side that makes it fairly identifiable.

metatarsal-phalangeal-joint

A basic dorsal view of the metatarsal and phalangeal bones in the right foot. Note that the hallux (first digit medially) has only a proximal and a distal phalanx whilst the other digits have a proximal, intermediate and distal phalanx (Source).

Phalanges

The foot phalanges are the same in design as the hand phalanges with heads, bases and shafts but are much shorter and squatter than the hand phalanges.  Again they come  in three rows, with 5 proximal phalanges4 intermediate phalanges and 5 distal phalanges;  it should be noted that the MT1 hallux has, as does the thumb (pollex), only the proximal and distal phalanges with no intermediate phalanx, and is remarkably more chunkier then either of the other four rays.

Each Proximal Phalanx displays a ‘single, concave proximal facet for the metatarsal head and a spool-shaped surface distally’ (White & Folkens 2005: 306).

Each Intermediate Phalanx displays a ‘double proximal articular facet for the head of the proximal phalanx’, and again have a trochlea shaped distal articular facet (White & Folkens 2005: 306).

Each Distal Phalanx displays a double articular proximal facet for the head of the intermediate phalanx and a terminal tip of the bone, resulting in a non-articular pad (White & Folkens 2005: 307).

These phalanges are all much shorter than their companions in the hand, with the foot phalanges having a more circular shaft cross section compared to the D shape  shaft of the hand phalanges.  Foot phalanges generally display a more constrictive shaft than hand phalanges, although it can be difficult to side them and it is best done with a full replica or whole specimens for comparative analysis (White & Folkens 2005: 308).  

Further Online Sources

  • A detailed map of each element and the surrounding musculature (as well as relaxing classical music!) can be found on the website of the UMFT Department of Anatomy and Embryology site.  Be aware there are detailed anatomical prosection and dissection diagrams, but it is a free, fascinating and wonderful source (and with the music especially relaxing!).
  • A number of websites have detailed diagrams and photographs of the foot from a medial/lateral and a dorsal/planar view, including this site and this one.
  • Finally, do you know your tarsal bones? Test yourself here!

Bibliography

Brothwell, D. R. 1981. Digging Up Bones: The Excavation, Treatment and Study of Human Skeletal Remains.  Ithica: Cornell University Press.

D’Août, K., Pataky T.C., De Clercq, D. & Aerts, P. 2009. The Effects of Habitual Footwear Use: Foot Shape and Function in Native Barefoot Walkers. Footwear Science1 (2): 81. doi:10.1080/19424280903386411 

D’Août, K., Meert, L., Van Gheluwe, B., De Clercq, D. & Aerts, P. 2010. Experimentally Generated Footprints in Sand: Analysis and Consequences for the Interpretation of Fossil and Forensic Footprints. American Journal of Physical Anthropology141: 515–525. doi: 10.1002/ajpa.21169

Gosling, J. A., Harris, P. F., Humpherson, J. R., Whitmore I., & Willan P. L. T. 2008. Human Anatomy Color Atlas and Text Book. Philadelphia: Mosby Elsevier.

Jarmey, C. 2003. The Concise Book of Muscles. Chichester: Lotus Publishing. 

Jurmain, R. Kilgore, L. & Trevathan, W.  2011. Essentials of Physical Anthropology International Edition. London: Wadworth.

Larsen, C. 1997. Bioarchaeology: Interpreting Behaviour From The Human Skeleton. Cambridge: Cambridge University Press.

Marsland, D. & Kapoor, S. 2008. Rheumatology and Orthopaedics. London: Mosby Elsevier.

Mays, S. 1999. The Archaeology of Human Bones. Glasgow: Bell & Bain Ltd.

White, T. & Folkens, P. 2005. The Human Bone Manual. London: Elsevier Academic Press.

Skeletal Series Repository, Amongst Other Things…

17 Jul

I’ve recently updated this blog with a side page, the Human Skeleton tab, for the skeletal series posts.  It can be found just next to the ‘About’ section.  Here you can handily find all the posts that I have wrote so far about the bones in the human body as used in the study of human osteology in archaeological contexts.  The posts discuss the human body in easily recognisable sections (such as leg, arm etc), and the contents include information on how to recognise and name various elements, anatomical landmarks and what to expect if you have the pleasure of digging them out!

Hopefully the series will give you enough information on how to differentiate and recognise the various type of bones in the human skeletal system, and also provide information on how individual bones fit together as whole in the skeletal system.

Meanwhile I’m currently back home relaxing and reviving myself after the 2nd semester of the masters program.  Shortly I’ll be heading out to visit our nearest continental neighbour, France, with the family for a week or two, so you may not hear from me in a while.  I am hoping that there will be a further guest blog or two in the near future, but I’ll be back to write about the next entry in the skeletal series, the human foot (Pes), soon enough.  In the meantime I’m sincerely hoping the dissertation has wrote itself whilst I am frolicking in the French countryside, but I highly doubt that will the case…

I recently had the great pleasure of excavating a medieval site in the lovely Peak District village of Castleton with the University of Sheffield.  Obstinately, the yearly project aims to find the medieval leper hospital in, or just outside the village, but there has been little luck this season of digging which was recently completed.  Whilst I only partook in a few days worth of excavating, it was with great pleasure I found myself in the great (wet) outdoors once again.

One particular highlight was the digging of a test pit in someone’s back yard under a gazebo with a dear friend, as the rain lashed down and the thunder rolled and roared overhead.  Minutes after the downpour the bright rays of the sun penetrated through the dark clouds and the backdrop of the 12th century medieval castle high up on the hill became clear for all to see, it was an immense sight for sore and tired eyes!  The excavation provided immense relief from sitting at a keyboard and it reminded me why I love field archaeology, and archaeology in general, so much.

Across my travels online I have had the pleasure of reading the adventures of various archaeologists recording their views of the sites they have dug at.  A particular favourite can be found at The Facts of My Ignorance site, a delightful read of Callum Dougan’s traipse across Mediterranean and Levantine archaeological sites, volunteering in various countries and at various digs as he goes.  His entry on the City of David project is enlightening, and revealing.  I have heard of this site before through friends who are studying for the MA in Biblical Archaeology here at Sheffield, and it seems archaeology will forever be tied in with politics, particularly in light about out who funds archaeology and why.

Over at Amateur Archaeologist, an impressive self leaner has collated a vast range of online archaeological and linguistics archive as well as writing detailed articles on a vast range of interests from Egyptian archaeology to Mesoamerican linguistics, cultural heritage management  to archaeological ethics amongst other topics.

I haven’t mentioned it yet on this blog, but Dr Fitzharris’s The Chirurgeons Apprentice is a site to watch out for!  It is an amazing repository and archive of detailed research on the ‘early modern chirurgeons’, the forerunners to today’s medical surgeons.  This site never disappoints and provides some fascinating insight into what terrors awaited the 17th century person if they ever happened to have an accident or become ill.  The subtitle perhaps says it all- ‘A website dedicated to the horrors of pre-anaesthetic surgery’.

Up next is Robert M. Chapple’s site who is a professional field archaeologist based in Northern Ireland.  On his site are a number of interesting articles on Irish archaeological sites he himself has dug at, alongside various posts on archaeology in the wider world.  His entry on his own ‘Transit Van experiment‘ is edifying, and revealing, about the state of theoretical and field archaeology.

Meanwhile Hazelnut Relations is a blog ran by the PhD student Marcel Cornelissen at the University of Zurich.  It focuses on use wear analysis of microlithic tools across the Mesolithic-Neolithic (Pre) Alpine Central Europe.  While his blog does focus on this topic, it also carries a much broader selection, and the author has many years experience in field archaeology in various European countries.

Finally we have Wunderkammer, a tumblr blog dedicated to arresting medical/historical images.  The byline, ‘a curiosity cabinet of (un)natural wonders’ intrigues, and the site does not disappointment.  One perhaps not for the faint of heart.

I’ll be back in a while, hopefully with a few different articles on palaeopathology, and the next instalment of the skeletal series.  In the meantime au revoir!

Skeletal Series Part 10: The Human Leg

15 Mar

We shall continue our look at the human skeleton with the next installment of the Skeletal Series blog posts with a consideration of the leg elements.  Previously covered was the hip and we shall now cover the femur (upper leg), patella (kneecap) and the tibia and fibula (the two lower leg elements).  The evolution of the leg mirrors that of the arm, from ancient fins to rod bearing segments, and as per the arm the leg contains a single upper bone with two lower bones making up the limb ending in the quite unique foot or Pes (White & Folkens 2005: 255).

The femur is the human body’s longest and sturdiest bone that helps to take the whole weight of the body during ambulation (Schwartz 2007: 151).  The tibia is the larger of the lower leg bones and it is easier to tell it apart from its slimmer lateral partner, the long and angular fibula.  The patella is the body’s largest sesamoid bone, safely ensconced in its muscle pouch in the anterior portion of the knee.  The human knee is particularly interesting as it ‘locks’ when stood straight up and unlocks with the aid of the popliteus muscle by laterally rotating the distal femur, which helps critically stabilise the knee.

The basic bones of the human leg (Image credit: Sheri 2012).

Excavation

During excavation of the supine skeleton in-situ, the lower limb bones tend to survive well because of their structural design and bone density.  In extended burials, and dependent on burial and soil conditions, the lower limb bones are often well-preserved and relatively easy to distinguish from the rest of the body.  As always, care must be taken when excavating the soil on top of and around the lower body.  The fibula can often be found fragmented or broken due to its lateral positioning and the effect of the weight of the soil and associated tibia lying close to it (Larsen 1997).  Even in cremated or burned skeletal tissue samples, particular features and landmarks of the lower limb long bones can easily be identified, and sometimes even sided as larger fragments can sustain slightly higher temperatures and minimal warping (White & Folkens 2005).

A medieval cemetery excavation during the 2007 Brodsworth community project (Image credit: the universities of Hull & Sheffield field school).

Leg Anatomy and Elements

The lower limb in the modern human is an interestingly adapted limb to bipedal walking, and as such it has changed anatomically from our nearest cousins (the great apes) to cope with our locomotion (Jurmain et al. 2011).  In this section we’ll cover the basic gross anatomy of each bone with a more in-depth look at the knee component after.  As mentioned elsewhere (and on this blog herelong bone growth is typically through the distal metaphysis (distal border of the diaphysis of the limb) and its epiphysis through the growth plate.

Growth of the long bones in a juvenile knee joint (the femur is located proximally, with tibia distal and fibula laterally. (Image credit: Danna 2011).

Femur

The femur, as stated, is the longest limb bone with several distinctive bony elements.  It is a fairly distinct bone with a high level of robusticity and dense, compact bone due to it being the main supporting limb doing ambulation.  The head of the femur fits into the acetabulum of the hip bone (ilium, ischium and pubis bones).   Unlike the humerus and the glenoid cavity joint, it has a direct ligament attachment between femoral bone and acetabulum, the ligamentum teres, which fits it snugly from the fovea capitis depression on the femoral head into the hip joint, helping to stabilise the joint (White & Folkens 2005: 255).  It is also heavily walled with muscles, from the trunk of the torso down to the knee, with the gluteal (lateral-posterior),  adductors (medial), quadriceps (anterior) and hamstring (posterior) muscle groups acting on the bone at various points (Gosling et al. 2008).  

Main anatomical landmarks of the femur.  For further information see Hawks 2011.

The main osteological features found on the femur include the greater and lesser trochanter’s, which are found in the proximal half of the femur, just below the femoral neck.  The greater and lesser trochanter’s act as muscle attachment sites for the gluteal muscles, amongst others, and sometimes a third trochanter can been seen just distal of the lesser (White & Folkens 2005).  Directly posterior, and running down the length of the shaft of the femur, is the linea aspera, one of the main attachment points for a variety of muscles, including the vastus and adductor muscle groups.

At the proximal femoral end the linea aspera collects the spiral, pectineal and gluteal lines (White & Folkens 2005: 257).  The lateral and medial condyles mark the distal articular surface with the tibia bone of the lower limb.  Alongside the medial edge of the medial epicondyle (just above the medial condyle) lies the adductor tubercle, the insertion point for the adductor magnus muscle (Gosling et al. 2008: 260).  The femur can be easily sided as the trochanters are medial and posteriorly positioned, with the linea aspera running directly posteriorly and the adductor tubercle located medially on the medial epicondlye.  The mid-section shaft of the femur is tear shaped, with the round body in the anterior position and the top of the  ‘tear’ pointing posteriorly.

Patella

The patella is the human skeletal systems largest sesamoid bone, and can be found in the anterior muscular pouch on the knee joint, anchored by the quadriceps tendon and patellar tendon on the distal anterior femoral surface (see diagram below).  It does not attach or articulated directly with any other bone.  The patella functions to ‘protect the intricate muscles and ligaments inside the knee joint, to increase area of contact between the patellar ligament and the femur, and to lengthen the lever arm of the quadricep muscles’ (White & Folkens 2005: 270).  The apex of the patella is the most distal point of the bone, and the smooth posterior articular facet rides the ligaments and muscles located anteriorly of the distal femur.

The complex knee joint and associated musculo-skeletal anatomy.  See Roberts & Manchester (2010) for palaeopathological lesions of the knee, especially osteoarthritis. (Image credit: Wikipedia 2012).

Tibia

The tibia is a distinctly shaped bone with an proximal medial and lateral condyles, medial and laterally intracondylar eminence’s (set posteriorly on the superior surface), an anterior proximal tibial tuberosity, the curved ‘tri-blade’ of the body (anterior, medial and posterior crests, with the medial malleolus marking the distal extremity of the bone (White & Folkens 2005: 273-79).  The landmarks on the tibia represent muscle origin and insertion points, such as the soleal line on the posterior aspect of the proximal tibia, which represents the soleus muscle origin.  The tibia is connected to the laterally positioned fibula with a strong interosseus membrane connecting the two throughout the length of the fibula, with articulations at the proximal and distal segments of the tibia (Gosling et al. 2008: 277).  Distally, the tibia articulates with the talus, the first tarsal bone of the foot.  To easily side the tibia, the malleolus is located on the medial distal aspect of the tibia, and the tibial tuberosity represents the anterior facing proximal end of the bone.

Labelled Tibia and Fibula.

The main anatomical landmarks of the right tibia and fibula, with the anterior position on the left and the posterior on the right hand side. (Image credit: Wikipedia 2012).

Fibula

The fibula is the thinner of the two lower legs bones, and does not bare any substantial weight (White & Folkens 2005).  It’s primarily importance is providing the lateral border of the ankle joint, with which it articulates with the calcaenous bone.  The head of the fibula, located superiorly, can be easily complicated with the distal malleolar articular surface, and to add to the woes of identification, the body of the fibula, without the proximal or distal segments, is nearly impossible to identify because of its irregularity.  The interosseous crest is located medially, and serves as the attachment for the interosseus membrane which spans between the length of the tibia and fibula.  To side an intact fibula quickly, use the posterior facing malleolar fossa, which can be found on the distal articular surface of the fibula.  The fibula has also been used as marker of sex (Sacragi & Ikeda 1995) and although this method is rarely used, it could be useful in a forensic or archaeological context where the skeletal remains may be limited.

Further Information

  • Although not mentioned here, please take the time to get associated with the fleshy articular pads between the femur and tibia (be aware as this is a fleshed photo).

Bibliography

Gosling, J. A., Harris, P. F., Humpherson, J. R., Whitmore I., & Willan P. L. T. 2008. Human Anatomy Color Atlas and Text Book. Philadelphia: Mosby Elsevier.

Hawks, J. 2011.  Femur: major landmarks and how to side it. From www.johnhawks.net. Accessed 2012.

Jurmain, R. Kilgore, L. & Trevathan, W.  2011. Essentials of Physical Anthropology International Edition. London: Wadworth.

Larsen, C. 1997. Bioarchaeology: Interpreting Behaviour From The Human Skeleton. Cambridge: Cambridge University Press.

Roberts, C. & Manchester, K. 2010. The Archaeology of Disease Third Edition. Stroud: The History Press.

Sacragi, A & Ikeda, T. 1995. Sex Identification From The Distal Fibula. International Journal of Osteoarchaeology. 5: 139-143. (access required).

Schwartz, J. H. 2007. Skeleton Keys: An Introduction to Human Skeletal Morphology. New York: Oxford University Press.

White, T. & Folkens, P. 2005. The Human Bone Manual. London: Elsevier Academic Press.

Skeletal Series Part 9: The Human Hip

22 Jan
In this post I shall be discussing and looking at the three main elements that make up the human pelvis (or the pelvic girdle, a homology to the shoulder girdle).  The bones that make up the pelvis are the Ischium, Ilium & the Pubis.  The Sacrum has been discussed in an earlier post on the spine.  During the development of the hip, these three elements remain singular, fusing together during adolescence to become one single unit during early maturity to become the Os Coxa (White & Folkens 2005: 246).

The main elements in the human hip, and as a whole Referred to as the Os Coxa. NB acetabulum faces laterally.

The hip is a fantastic wealth of skeletal knowledge.  The two most basic and fundamental traits of the person, the age and biological sex of the individual, can be found in articles by Brooks & Suchey (1990) and by Patriquin et al. (2005), which both use morphological features of the pelvis to estimate sex and age of the individual under study.  Many muscles also insert and attach along the borders, rims and edges of the pelvis, especially anchoring those that are key in movement during bipedal locomotion (Schwartz 2007: 147).  The hip, and its component parts, are most distinctive in shape and size.  Odd looking, hard to figure out at first, and looking like nothing else (a top heavy hourglass is one view), the Os Coxa can can be hard to identify and orientate, especially in smaller fragments.

Juvenile ilium (top), ischium (bottom right) and pubis (bottom left) (Image credit: Bone Clones 2006).

 
Excavation
 
Unfortunately during excavation, the first thing that the pick ax, spade or trowel is likely to hit is the most anterior part of the hip, the pubic symphysis, as in most human burials the body lies prone and face up, in a supine burial (see Brothwell: 3 for other burial positions).  This can lead to destruction of this joint, which can lead to loss of information on age and sex of the individual.  However, during normal inhumation excavation the grave cut can be clearly distinguished, and a pattern of working from top to bottom or bottom to top can help limit the amount of damage during excavation (White & Folkens 2005).

The author excavating a Medieval skeleton in Germany in 2011. Note the damaged anterior aspect of the Pubic Symphysis, which is outlined in red.

 
Pelvic Anatomy and Elements:
 
Acetabulum
 
The acetabulum  makes up the socket to receive the head of the femur (thigh), and is equally made up of a portion of the three elements of the hip which fuse during early adolescence.  This joint is necessarily much more stable then the non-weight bearing shoulder joint- it is much deeper, has the ligamentum teres (a ligament that attaches to the femoral head and the hip) and is covered by much stronger and denser musculature (White & Folkens 2005: 246).  As the main weight bearing joint, the bone is also much denser with thicker cortical bone.
 
Ilium
 
The ilium is the largest of the three parts of the os coxa, and sits superiorly above the ischium and pubis, and it is often described as ‘blade like’ (Schwartz 2007: 148) as it is a thin but strong plate of curved bone.  On the lateral side of the blade, three gluteal lines (anterior, inferior & posterior) are visible which are the muscle attachment sites for the large gluteal muscles.  The main landmarks along the upper ridge is the iliac crest, which can be felt on yourself, and begins anteriorly with the anterior superior iliac spine and ends in the posterior superior iliac spine (White & Folkens 2005: 247).  The auricular surface of the medial ilium articulates with the sacrum (and is a very useful age estimator- Buckberry & Chamberlain 2002).  The greater sciatic notch is also generally a good indicator of the biological sex of the individual.

Anatomical landmarks on the right hip (Image credit: Pearson Education 2010).

Ischium
 
The ischium is the butt bone, literally the bone which takes the weight whilst we are sitting on a chair!  The key features of this element of the hip is that a lot of muscles attach to the posterior ischial tuberosity.  The ischial tuberosity muscle attachments include the origins of the hamstring muscles (semimembranosus, semitendinosus, adductor magnus & biceps femoris) (White & Folkens 2005).  Alongside the pubic bone, the ischium also includes the obturator foramen, a gap (in life covered by a membrane) where a number of internal gluteal muscles converge and provide stability for the hip.
 
Pubis
 
The pubic bone makes up the anterior part of the hip as a whole and includes a cartilaginous joint, just above the genitalia in living individuals.  The pubic symphysis, as this joint is called, is also a good indicator of biological sex because of the shape below it (the  pubic arch) and also age because of age related changes in the bony surface of the pubic symphysis (Schwartz 2007: 230).  The pubic bone also includes a superior and inferior pubic ramus, literally the corpus of the bone, which help support numerous muscle attachments, namely the adductors (adductor brevislongus & magnus) of the medial compartment of the thigh.
 

The  major landmarks of the pelvic bones in anatomical position.

Discussion

For the discussion on the hip we shall talk about septic arthritis (SA).  SA is mostly common in the hip and knee, and rarely presents in the elbow or shoulder.  Although it is rare in the archaeological record, it is nonetheless recorded in a number of examples (i.e. Yukon individuals in the Natural Museum of National History in Washington, US), and it pays to be able to recognise it (Roberts & Manchester 2010: 154).  The condition is fairly uncommon, and the aetiology of SA is when an infection reaches a joint, normally through one of three means- i) the haematogenous route (most common), ii) a penetrating injury or iii) its spread from metaphysis (Marsland & Kapoor 2008).  The bacteria, or germ, normally infects the synovial fluid which may be inflamed from disease or trauma, and ‘proliferation of bacteria cause an inflammatory response by the host with numerous leucocytes migrating into the joint’ (Marsland & Kapoor 2008: 136).

Main outcome of septic arthritis (Image credit: http://www.aidmyarthritis.com).

At this point the variety of enzymes and breakdown products that are produced helps to damage the articular cartilage very quickly, and if left will produce permanent damage (Waldron 2009: 89).  The prognosis is good if treated promptly, however in the archaeological record this is quite unlikely due to the high risks of re-infection and complications such as joint destruction, avascular necrosis (mostly at the hip) & the ‘seeding of infection’ to other places (Marsland & Kapoor 2008: 137).  Again, the diagnosis of septic arthritis in the archaeological record is hindered by confusion with similarities to tuberculous infection, and difficulties in diagnosing multiple diseases that may present themselves on any one individual (Roberts & Manchester 2010: 154).  In the hip, the surface and surrounding area (lunate surface) of the acetabulum would be highly damaged, with a rough appearance and feeling as the bony lytic destruction took hold (Waldron 2009).

Bibliography

Brooks, S. & Suchey, J. M. 1990. Skeletal age determination based on the os pubis: a comparison of the Acsádi-Nemeskéri and Suchey-Brooks methods. Human Evolution 5– N.3: 227-238.

Brothwell, D. R. 1981. Digging Up Bones: The Excavation, Treatment and Study of Human Skeletal Remains.  Ithica: Cornell University Press.

Buckberry, J.L. & Chamberlain, A.T.  2002.  Age estimation from the auricular surface of the ilium: a revised methodAmerican Journal of Physical Anthropology 119: 231-239.

Larsen, C. 1997. Bioarchaeology: Interpreting Behaviour From The Human Skeleton. Cambridge: Cambridge University Press.

Marsland, D. & Kapoor, S. 2008. Rheumatology and Orthopaedics. London: Mosby Elsevier.

Mays, S. 1999. The Archaeology of Human Bones. Glasgow: Bell & Bain Ltd.

Patriquin, M.L., Steyn, M. & Loth, S.R. 2005.  Metric analysis of sex differences in South African black and white pelvesForensic Science International 147: 119-127.

Roberts, C. & Manchester, K. 2010. The Archaeology of Disease Third Edition. Stroud: The History Press.

Schwartz, J. H. 2007. Skeleton Keys: An Introduction to Human Skeletal Morphology. New York: Oxford University Press.

Waldron, T. 2009. Palaeopathology: Cambridge Manuals in Archaeology. Cambridge: Cambridge University Press.

White, T. & Folkens, P. 2005. The Human Bone Manual. London: Elsevier Academic Press.

Skeletal Series Part 8: The Human Hand

17 Jul

Common names for fingers of the hand.

To my mind the human hand is a real marker of humanity.  Alongside the anatomy of the foot, the human hand is especially designed for certain actions.  Whereas the foot has changed to accommodate long distance bipedal walking, the human hand has developed to be extremely sensitive with dexterous movement.  The mammalian order of the primates are the only animals with true hands, with humans, chimps and apes having two opposable thumbs and great gripping potential (Jurmain et al 2010).  As the modified end to the ancestral fish fin, the human hand has retained the 5 original number of digits whilst a variety of animals have gone through reduction and modification in the number of their digits (e.g. horses, bats, pigs) (White & Folkens 2005: 225).  The sense of touch is anchored in and from the hand.

Excavation

As ever careful excavation of the burial should take place when necessary.  The small bones located in the human hand can be hard to spot, especially distal phalanges as they tend to be very small (see diagram).  It is likely that most of the metacarpals and the larger phalanges will probably survive, however to spot the carpals care is needed as these can often look like stones.  It can be very difficult to imagine how the bones would look in articulation during excavation, and as such all material should be saved for closer inspection rather then losing valuable information (Larsen 1997). A key note is to know that the hand bones will often be spread over a wider area, unlike the foot bones.  On excavation in the summer of 2011 in Germany I realised firsthand how spread out they could be, with the phalanges of one supine burial found next to the leg bones, spread over the hip, with some lingering inside the chest cavity; the bones were all over!

Hand Anatomy and Elements

Overall there are 27 bones present in the hand.  The bones in the hand are typically classed into three groups; the CarpalsMetacarpals & the Proximal, Intermediate & Distal Phalanges.  The thumb is often called the Pollex, whilst each finger is usually referred to as a ray, starting on the index finger.  As discussed previously, the carpals articulate with the distal ends of the ulna & radius (White & Folkens 2005).

Classification of the bones in the human hand.

It is an interesting fact that most of the bones in the human body come from the hands and the feet, as such have both a large number of phalanges.  As outlined above, and discussed below, the carpals contain 8 bones, the metacarpals 5 bones, the proximal phalanges 5 bones, the intermediate 4 bones & the distal phalanges 5 bones.  The hand is used for both gross motor skills and fine motor skills with the fingertips containing some of the densest bundles of nerves (Wikipedia 2011).  Interesting the hand can reach almost anywhere on the persons body, discounting a small patch on the back and the elbow and lower arm the hand is located on.

Name of each individual element, and the anatomical position in comparison with X -Ray of a human hand.

Carpals (8 Elements)

The carpals make up the wrist, and are positioned as two tiers of four bones.  Each of the bones have a characteristic  shape, and recognizing the shapes in diagnosis of the separate carpal bones.  The first proximal row consists of (from right to left in a right hand) the Scaphoid, Lunate, Triquetral & the Pisiform bones.  The second distal row consists of the Trapezium, Trapezoid, Capitate and the Hamate bones (White & Folken 2005: 288-233).  I advise you to click on the wikipedia links to see each element by itself, as it would take too much space up here!

Carpals in articulation.

Scaphoid– The scaphoid bone is shaped like a boat, and is one of the largest carpal bones.  It is the most lateral and proximal carpal bones, with a both a major concave and convex surface for the articulation, with the head of the hamate and the articulation surface of the distal radius.

Lunate– The lunate takes the form of a crescent moon.  Its deeply concave surface articulates with the capitate, whilst articular point opposite shares the distal radius with the scaphoid surface.

Triquetral-The triquetral is the third bone in the carpal row and its main distinguishing feature is the three articular surfaces.

Pisiform– The pisiform is a pea shaped bone and the smallest of the carpal bones.  It actually develops inside a tendon, and as such does not articulate with any other bone directly.

Trapezium– The trapezium is an irregularly shaped bone of medium size and is most distinguished by the largest facet and saddle shaped articular surface for the base of the first metacarpal.

Trapezoid– The trapezoid bone is boot shaped, and it is the smallest bone in the distal row.  It articulates distally with the second metacarpal (White & Folkens 2005: 231).

Capitate– The capitate is a larger carpal bone that articulates distally with the metacarpal 3, 2 and sometimes 4.  The end is squared off whilst the proximal end is rounded.

Hamate– The hamate is the carpal bone which has the hook shaped non articular projection called the hamulus.  This is a key aid in the diagnosing the hamate carpal.  The hamulus is the fourth attachment point for the flexor retinaculum.

Metacarpals (5 Elements)

The metacarpals are numbered from MC1 (thumb) to MC 5 (little finger).  As White & Folkens discuss (2005: 233), the metacarpals are all tubular bones with rounded distal articular heads with the more rectangular proximal ends.  As such they are most easily identified and sided by the morphology of the bases.

Metacarpals of the human hand in articulation, where 1 represents the pollux.

Metacarpal I:  The first metacarpal is the shortest, broadest & more robust of the five.  The singular proximal articular surface is saddle shape which corresponds to the fact on the trapezium (White & Folkens 2005: 236 & here after for the metacarpal section).

Metacarpal II:  The second metacarpal is normally the longest of the five with the base presenting as along curved blade like wedge.

Metacarpal III:  The third metacarpal lies at the base of the middle finger and it is the only metacarpal that has a sharp projection, called the styloid process, at its distal base.

Metacarpal IV:  The fourth metacarpal is shorter and more gracile then the MC 2 or MC 3 with a fairly square base with 3 or 4 articulating facets.

Metacarpal V:  The fifth metacarpal is the thinnest and shortest of the non-pollical metacarpals (ie first or MC 1 rays).

As a reference for siding either in the lab or on site I highly recommend White & Folkens 2005, this blog entry can be only just a short guide.

Proximal, Intermediate & Distal Phalanges (14 elements)

The phalanges consist of the last three digit of each finger (only two for the thumb).  They are all shorter then the metacarpals and tend to be somewhat flattened as well.  The thumb phalanges are shorter and thicker then the other rays, whilst it also lacks a intermediate phalanx.

Proximal, intermediate and distal phalanges (MMG 2004).

Proximal Phalanges:  Each of the proximal phalanges has a concave proximal articular facet for the metacarpal head. The thumb proximal phalanges is easily recognizable for its stout and squat appearance.

Intermediate Phalanges:  Following the proximal phalanges is the intermediate phalanges which has a double articular proximal facet for the head of the proximal phalanx, whilst each also has a distal articular facet.

Distal Phalange:  Each of the distal phalanges has a double proximal articular facet for the intermediate phalanx.  The end of these phalanges terminate in the distal phalangeal tuberosity, which is a key indicator that you’ve found a pinky!

As above, please note my main source is White & Folkens (2005) Human Bone Manual.

Brief Discussion

As mentioned above in the beginning of this entry, I noticed first hand in Germany on placement whilst excavating in a medieval cemetery of how dispersed the carpals, metacarpals & phalanges can be in a grave context, especially in a supine burial context.  Due to the nature of the position of the body during burial and the subsequent flesh decomposition and natural earth movements, the delicate bones of the hand can often move around.  Care really is needed to recover each of the bones that survive.  I include below a photograph I took at the Domersleben medieval cemetery excavation in the summer of 2011 to present how the hand bones had moved around and displaced since internment of the body.

Note the position of the metacarpals and phalanges in this Medieval cemetery burial.

The recovering of the hand bones depends on the burial context (supine, extended or flexed burial, whether cremation was carried out etc), and of careful excavation around the areas where you expect the recovery of hand bones themselves (Larsen 1997).  Although the carpals can be hard to identify and to side, it is well well worth spending a good few days with a reference sample to make sure you understand the basic anatomy and main skeletal landmarks of the individual elements.   The evolution of the human hand has been critical to the way Homo sapiens both express themselves and how they interact with the environment.  Without the incredible grasping powers of the pollex, it is unlikely Homo sapiens and other later hominids would have been able to create such intricately carved lithics or artworks such the Upper Palaeolithic cave site of Lascaux in modern day France (Jurmain et al. 2011).

Further Information

Bibliography

Jurmain, R. Kilgore, L. & Trevathan, W.  2011. Essentials of Physical Anthropology International Edition. London: Wadworth.

Larsen, C. 1997. Bioarchaeology: Interpreting Behaviour From The Human Skeleton. Cambridge: Cambridge University Press.

Marsland, D. & Kapoor, S. 2008. Rheumatology and Orthopaedics. London: Mosby Elsevier.

Mays, S. 1999. The Archaeology of Human Bones. Glasgow: Bell & Bain Ltd.

Roberts, C. & Manchester, K. 2010. The Archaeology of Disease Third Edition. Stroud: The History Press.

Waldron, T. 2009. Palaeopathology: Cambridge Manuals in Archaeology. Cambridge: Cambridge University Press.

White, T. & Folkens, P. 2005. The Human Bone Manual. London: Elsevier Academic Press.

Skeletal Series Part 7: The Human Arm

30 May

In this post we shall focus on the main bones located in the arm.  They are the Humerus, Radius & Ulna.  The previous post on the shoulder elements (Scapula & Clavicle) can be found here.  It should be noted that the bones discussed  in this post, known as the forelimb, are the homologs to the bones in the leg, the hind limb.

The Human Arm, And The Bones Under Discussion

Articulation of arm with the distal humerus and proximal radius and ulna making the elbow joint (Image credit: Wikipedia 2011).

Excavation

As noted in previous Skeletal Series posts care should be taken with excavating human remains, and the maxim that ‘context is everything’ should be well noted with detailed plans of the in-situ remains made.  It is likely that some damage will have occurred to the smaller ulna and radius as they are more fragile then the larger and denser humerus bone.  A record of the condition of the bones should be made, alongside what contextual information is available (Mays 1999, White & Folkens 2005).

Arm Anatomy & Function

The humerus articulates proximally with the scapula and clavicle, as discussed in the last entry (See diagram below).  The distal humerus articulates with the proximal radius and ulna head.  This articulation makes up the elbow, which will be discussed in detail below.  At the distal end of the radius and ulna the carpals are located, which make up the wrist.  These, alongside the other elements in the hand, will be discussed in the next Skeletal Series post.

The individual brachium and antebrachium skeletal elements and major skeletal landmarks, as seen in articulation with the full limb (image credit: Wikipedia 2011).

The function of the forelimb is to provide a rigid limb to help hold, grab and move surfaces and objects.  The shoulder girdle and arm bones have moved away from our evolutionary history of weight-bearing limbs, and have become essential in helping humans to manipulate and move objects with astounding dexterity (Jurmain et al 2011).

Elbow Joint

The elbow joint (image credit: CK-12).

This joint in particular is important to understand as it is a key hinge joint.  The diagram below helps to mark out the distal humerus with the proximal radius and ulna in articulation.  The elbow is one of the strongest points of the body in terms of bone hitting strength.  The two main movements of the elbow are flexion and extension of the humerus and ulna, alongside the pronation of the radius and ulna in turning the arm over (White & Folkens 2005).  The joint itself has a large synovial membrane that protects the articulation points of the bone, whilst the main muscles involved are the Brachialis & Brachiaoradialus (at the anterior side) and the Triceps Brachii & Aconaeus towards the posterior side.  The lateral and medial muscles are the Supinator and Extensor muscles, alongside the Flexor muscles and Flexor Carpi Ulnaris muscles (White & Folkens 2005, but also here).

Anterior elbow joint in articulation, highlighting the major skeletal landmarks of the three bones that make up the joint. Image credit: here.

The Humerus

The humerus is the largest bone in the upper body, and ‘compromises of a proximal end with a round articular head, a shaft, an irregular distal end’ (White & Folkens 2005: 203).  It articulates with the Glenoid cavity (or fossa) of the scapula, and as mentioned, the proximal radius and ulna at the distal end.  The humerus head faces medially, whilst the surgical (or anatomical) neck is the groove that encircles the head for the attachment of the joint capsule (White & Folkens: 203-4).  Both the Greater and Lesser Tubercle are muscle attachment eminences that help move and rotate the upper arm.  On the Greater tubercle (the more posterior and large of the tubercles) rugosities for the insertion of the rotator cuff muscles are round, which help in rotation and adduction and abduction of the arm (White & Folkens 2005).

Main skeletal landmarks of the humerus (click to enlarge). Image credit: Google 2011.

The Shaft of the humerus is variably triangular in section, going from more cylindrical at its proximal end to more triangular in shape towards the distal end (Larsen 1997).  The Deltoid tuberosity is an important feature located on the lateral side of the shaft.  It is the insertion site of the deltoideus muscle, and is recognised by its roughened appearance.  Towards the distal end of the humerus we have several key features that are easily identifiable in recognising this as an upper limb element.

The Olecrannon Fossa is the largest of three hollows located posteriorly at the distal end, and accommodates the olecrannon process of the ulna during forearm extension.  The Capitulum is the rounded eminence that forms the lateral portion of the distal humeral surface, and it articulates with the head of the radius (White & Folkens 2005: 211).  The Lateral and Medial Epicondyle are the non articulating projections of bone, the medial is more prominent than the lateral epicondyle.

The humerus is relatively easy to recognise by the certain features picked out above, but parts can be confused with the tibia and femur.  With the femur, the head has a distinct depression called the Fovea Capitis whilst the humerus lacks this feature (Mays 1999).  The humeral shaft is smaller and less triangular than the tibial shaft.  When siding remember that the olecrannon fossa is posterior and the medial epicondyle is larger, and the humeral head faces medially.  The deltoid tuberosity is found laterally (White & Folkens 2005: 214).

The Ulna

The Ulna is the longest and thinnest bone of the forearm, and articulates proximally with trochlea of the humerus and head of the radius.  Distally, it articulates with the ulnar notch of the radius and an articular disk that separates it from the carpals.  The Olecrannon of the ulna is located on the most proximal part of the ulna; it is the insertion point for triceps brachii muscle.  The Trochlea Notch articulates with the trochlea articular surface of the humerus.  The Coronoid Process is the ‘anterior beak shaped projection at the base of the semilunar notch’ (White & Fokens 2005: 219).  The Radial Notch  is the small articular surface for the radius, and is located along the lateral side of the coronoid process.  The Radial Articulation (Ulna Head)  is the distal, lateral round articulation that conforms to the ulna notch on the radius.  The distal and proximal ends of the ulna are fairly distinctive and indicative of the element, however as White & Folkens (2005) and May (1999) point out, the shafts could be mistaken for radial or fibular shafts.

The ulna and the radius and their associated skeletal landmarks, click to enlarge. Image credit: Wikipedia 2011.

The Radius

The radius is a relatively small bone and shortest of the three in the forelimb.  Its name was gained for the action it goes through as the ‘turning movement about the capitulum of the humerus’ (White & Folkens 2005: 214).  At the proximal end it articulates with the humerus and medially with the ulna on both proximal and distal ends, whilst also distally it articulates with two carpal bones of the wrist.

The Head is a round articular structure at the proximal end of the radius, and as stated above articulates with both the humerus and ulna.  The Neck is a slender segment between the head and the radial tuberosity.  The Radial Tuberosity is a blunt rugged structure on the anteromedial site of the proximal radius that marks the insertion for the biceps brachii muscle (Mays 1999).  The  Styloid Process is a sharp projection located on the lateral side of the distal radius whilst the Ulnar Notch is a concave articular hollow on the medial corner of the distal radius.

Discussion: Wrist Fracture

Colle’s fracture is a break at the distal end of the radius and ulna that results in a ‘dinner fork deformity‘ with dorsal angulation, and displacement of the fracture with radial angulation.  The counterpart to this is Smith’s fracture which is the same but the fracture is displaced in the opposite direction, ie palmar (Marsland & Kapoor 2008: 96).

Smiths fracture highlighting the displacement of the distal radius. Image credit: Wikipedia 2011.

These type of fractures often occur because of trips or falls onto outstretched hands, as an automatic safety device by the body.  In modern contexts they also happen in a variety of sport environments.  These types of breaks are often easy to treat with splints and plaster casts, although they sometimes require surgery to correct the breaks and/or angles.  The patients can often be left with a visible deformity, but likely without any pain whatsoever (Marsland & Kapoor 2008: 96).  In archaeological examples these type of fractures can be found in any number of contexts or cultures.  It is important to note that, as Larsen (1997) says, many human cultures’ skeletal series often exhibit these breaks, and it can shed light into pathways of differing lifestyles.  Larsen also notes that whilst there is a large osteological literature on injuries in comparison to more population based studies which would help to highlight inferences on accidents and conflict in both historic and prehistoric societies (1997: 109).

Further Information

Bibliography

Jurmain, R. Kilgore, L. & Trevathan, W.  2011. Essentials of Physical Anthropology International Edition. London: Wadworth.

Larsen, C. 1997. Bioarchaeology: Interpreting Behaviour From The Human Skeleton. Cambridge: Cambridge University Press.

Marsland, D. & Kapoor, S. 2008. Rheumatology and Orthopaedics. London: Mosby Elsevier.

Mays, S. 1999. The Archaeology of Human Bones. Glasgow: Bell & Bain Ltd.

Roberts, C. & Manchester, K. 2010. The Archaeology of Disease Third Edition. Stroud: The History Press.

Waldron, T. 2009. Palaeopathology: Cambridge Manuals in Archaeology. Cambridge: Cambridge University Press.

White, T. & Folkens, P. 2005. The Human Bone Manual. London: Elsevier Academic Press.

Skeletal Series Part 6: The Human Shoulder

16 May

This post will focus on the scapula and the clavicle elements of the shoulder girdle.  The scapula provides the back of the shoulder, and the clavicle articulates with the sternum (discussed in previous post) and the top of the arm (the humerus).  The humerus will be discussed in a subsequent post on the elements of the arm.

Excavation

Together with previous posts on the spine and rib cage, this post makes up the ‘trunk’ of the human body.  As ever, care should be taken during excavation & examination.  Both the scapula and the clavicle are fairly tough elements and survive well.  The body and medial border of the scapula is liable to damage however as it is a thin blade of bone (Mays 1999).

On mainland Europe the study of anthropologie de terrain (the study and alignment of the body in a burial context) is often used, especially so in prehistoric sites.  Interestingly by examining the placement of the clavicle bones in burial, you can often tell whether a body has been covered in a shroud or likewise garment in the deposit of the cadaver.  The clavicles are often found near vertical in the upper chest cavity, which itself is often tightly bound.

The Shoulder Girdle Anatomy and Its Function

The shoulder girdle consists of the scapula bone, and the clavicle, which provide support and articulation for the humerus.  They also  anchor a variety of muscles which help rotate, move and flex the humerus.  The joint of the humerus and scapula is called the Glenohumeral Joint, the acromion process (see below) and clavicle is the  Acromioclavicular Joint, & the sternum and clavicle is called the Sternoclavicular Joint (Marshland & Kapoor 2008: 206).  The clavicle functions as the strut for the shoulder whilst the scapula helps provide anchor points for the larger muscles as well as the loose ranging ‘cup’ for the humeral head (White & Folkens 2005: 193).  Because of the lateral placement of the forelimb on the upper human body, we have evolved away from our nearest ancestors, as the forelimb placement gradually changed (See Afarensis article below in relation to our recent hominid brothers).  The diagram below marks out the main features of the shoulder girdle-

Anterior view of the shoulder elements, note only the clavicle and scapula are discussed in this post (Image credit: Britannic Inc 2007).

The clavicle is easy to palpate in your own body, along the length of the bone whilst the scapula spine and acromial process (see below) can be palpated just adjacent medially from the top of either arm.

Clavicle

As for any shoulder element, there are two clavicles present in the human skeleton.  As demonstrated by the above and below diagram, the clavicle is a tubular S shaped bone that sits anteriorly in the shoulder joint and is easily palpated.  The clavicle is oval to circular in cross section (White & Folkens 2005: 193).   The main anatomical landmarks are featured in the diagram below.

Landmark features and muscle attachment sites for clavicle (click to enlargen). Image credit: Wikipedia.

The costal impression is a broad rough surface that anchors the costoclavicular ligament, which strengthens the joint.  The lateral side of the clavicle has two major attachment muscle sites for the trapezuis & deltoideus muscles (White & Folkens 2005: 193).  The clavicle articulates with the acromial process of the scapula at the lateral end, whilst at the medial end it articulates with the clavicular notch of the manubrium.  The clavicle is often broken during a trip or a fall as the bone is so close to the skin, and acts as a supporting strut (Marsland & Kapoor 2008).

There are a few main points to consider when siding a clavicle.  The medial end is rounded whilst the lateral side is flattened.  Most irregularities are roughenings are on the inferior edge of the bone, whilst the bone itself ‘bows anteriorly from the medial end, curves posteriorly at the midshaft and sweeps anteriorly again at the lateral flat end’ (White & Folkens 2005: 195).

Scapula

The scapula is a ‘large, flat, triangular bone with two basic surfaces; the posterior (dorsal) and costal (anterior, or ventral)’ (White & Folkens 2005: 195).  The bone articulates with the humerus at the glenoid cavity (or fossa), and the distal clavicle on a small facet on the acromion process (see below diagram).  The ‘coracoid process just anteriorly and superlaterally from the superior border of the scapula’ whilst the acromion process is the lateral projection of the scapula spine.  Both of these projection points provide anchoring points for a number of key muscle abductors, rotators and flexors, amongst others (White & Folkens 2005: 200).  The glenoid cavity provides the humeral head with great mobility because of how shallow the fossa is; however the arm can be easier to dislocate then the leg bones (Marshland & Kapoor 2008).  The scapular spine provides an anchor point for the acromion process, and it key in distinguishing the posterior aspect of the body.

Distinctive landmark features on the scapula (anterior view, lateral view and posterior view). Image credit: Wikipedia.

Interestingly scapula fractures are rare in the archaeology record, but when evident they are usually located in the blade of the bone.  They are usually marks indicative of interpersonal violence due to the posterior position and location (Roberts & Manchester 2010: 104).  However as pointed out above the blade is usually damaged before or during excavation due to its delicate nature.

Another feature to be aware of is the lack of fusion that can take place at the acromion epiphysis (growing plate).  The most famous case concerning the lack of fused acromional points in a  skeletal series are from the remains of individuals from the Tudor ship The Mary Rose.  Of the skeletons studied, 13.6% of their number had unfused acromions (see diagram above/below).  The reason suggested was that they represented the archers aboard the ship, and had practised since childhood which had prevented any fusion of the element because of the constant stress, strain and movement needed to be a top bowman (Roberts & Manchester 2010: 105).

Posterior shoulder anatomy showing the major muscle (supra and inferspinatus muscles). Image credit: source.

When siding and investigating a piece of suspected scapula bone, it should be noted that it is mostly a thin bone, and unlike the pelvis, there is no spongy bone sandwiched between the cortices.  The following is taken from (yes that’s right!) White & Folkens 2005, page 202, with some modification.

  • The glenoid cavity is teardrop-shaped, with the blunt end inferior.
  • An isolated acromion is concave on its inferior surface.  The clavicular facet is anteriormedially relative to the tip.
  • For an isolated coracoid element the smooth surface is inferior whilst the rough superior.  The anterior body is longer and thee hollow on the inferior surface faces the glenoid area.
  • The spine thins medially whilst it thickens towards the acromion.  The inferior border has a tubercle that points inferiorly, as seen in the above diagram.
  • On the posterior body there are several transverse muscle attachment sites.  These are usually quite prominent, and are key indicators in helping to visualise the orientation of the scapula.

Range Of Movement

Lateral view of the rotation of the shoulder joint. Image credit: Wikipedia.

Anterior view of the rotation of the shoulder joint. Image credit: Wikipedia.

An Arctic Case Study

There is a perception, garnered from the earlier descriptions of the Arctic aboriginal groups, that the native Eskimo groups were passive, of ‘quiet repose and lived in a state of non-violence’ (Larsen 1997: 131).  New bioarchaeological investigations are helping to provide data that is slowly leading to a revision in the review of those perceptions.

A Saunaktuk site, dated to the late 14th Century AD, located east of the Mackenzie Delta in the Canadian Northwest Territories has provided compelling evidence of violent confrontation between native groups (Larsen 1997).  As Larsen (1997: 132) discusses the skeletal remains of 35 Inuit Eskimo Villages represented at the site, it becomes clear that there is evidence for violent death and body treatment, which is indicated by extensive perimortem skeletal modifications.  A large percentage of the whole group are adolescents (68.6%), whilst all of individuals represented had not been purposefully buried.  It is suggested that the group represents a targeted selection whilst other adults where away from the site (Melbye & Fairgrieve 1994).

Studying the bones in anatomical position. Image credit: Google.

On the skeletons themselves, hundreds of knife cuts were evidenced.  These ranged from around the articular joints and neck vertebrae, which is indicative of decapitation and dismemberment (Larsen 1997).  As well as this there are numerous cuts on the facial bones on many of the victims, with cuts also present on the clavicles and scapulae as well (Melbye & Fairgrieve 1994).  Many of these cuts reflect an overall pattern associated with dismemberment, removal of muscle and other soft tissues as well as intentional mutilation.  There is the distinct possibility of cannibalism having been carried out at this site.

In particular, unique to this Saunaktuk skeletal series, is the ‘presence of gauges at the ends of long bones’ (Larsen 1997: 132).  The modifications of the gauges on the adult distal femora are consistent with oral tradition describing a type of torture where the victims knees were pierced and the individual dragged around the village by a cord passed through these perforations’ (Larsen 1997: 132).

We have to understand that there is a vast rich historical record that does help to provide a context for this group to group violence as recognised by the skeletal and oral records.  Violent interactions at this locality occurred between the groups, and intergroup violence has been recorded by many explorers for the Hudson Bay Company in the 18th century (Melbye & Fairgrieve 1994).  Other pre-contact sites such as Kodiak Island in Alaska, alongside the sites of Uyak Bay, Crag Point & Koniag Island there is also evidence of culturally modified human bone.  However, we must remember the context in which these actions had taken place.  There are a small selection of the overall number of ore-contact Arctic sites in this area.  Please refer back to previous posts by my guest blogger Kate Brown on the pre conditions and difficulties of diagnosing cannibalism.

Further Online Sources

Bibliography

Larsen, C. 1997. Bioarchaeology: Interpreting Behaviour From The Human Skeleton. Cambridge: Cambridge University Press.

Marsland, D. & Kapoor, S. 2008. Rheumatology and Orthopaedics. London: Mosby Elsevier.

Mays, S. 1999. The Archaeology of Human Bones. Glasgow: Bell & Bain Ltd.

Melbye, J. & S. I. 1994. ‘A Massacre And Possible Cannibalism In The Canadian Arctic: New Evidence From The Saunatuk Site (NgTn-1)’. Arctic Anthropology. Vol 31. No 2. PP 57-77. Wisconsin: University of Wisconsin.

Roberts, C. & Manchester, K. 2010. The Archaeology of Disease Third Edition. Stroud: The History Press.

Waldron, T. 2009. Palaeopathology: Cambridge Manuals in Archaeology. Cambridge: Cambridge University Press.

White, T. & Folkens, P. 2005. The Human Bone Manual. London: Elsevier Academic Press.

Skeletal Series Part 5: The Human Rib Cage

6 May

As we covered the vertebrae in the previous post in the skeletal series, we shall move on to the last elements in the axial skeleton (bar the clavicle and scapula in next post).  The elements of the appendicular skeleton will follow shortly.

Excavation

As before, great care must be taken when excavating the ribs.  I have carried out micro-excavation of juvenile remains, (when I volunteered at Humber Field Archaeology) that consisted of the vertebrae, half of the ribcage and parts of the pelvis in-situ, and it took a while.  During excavation of human remains on site, it is very unlikely that the rib cage will be in its natural anatomical position.  Due to the soil and weight of the earth above the body, and the movement in the intervening period between burial and excavation, the ribs are likely to be broken and misplaced.  As always keep a look out for finer skeletal finds.

The Rib Cage

The focus of this post will be the sternum, which is made up of the Manubrium, Corpus Sterni (or Gladiolus) and the Xiphoid Process alongside a look at the ribs, all of which help to form the rib cage.  It is necessary to note here that variation in the number of ribs, as of the vertebrae discussed previously, can differ in people and in archaeological populations (Mays 1999: 15).  The function of the rib cage, as the main upper part of the torso in the human body, is to protect the vital organs that lie within the protective enclave of the ribs.  They include the majority of the torso organs such as the heart, liver, lungs, kidneys and partially the intestines.  The rib cage also helps breathing by the function of the intercostal muscles lifting and lowering the rib cage, aiding inhalation and exhalation.  The ribs are attached dorsally to the vertebrae, with articulating facets for the tubercle end of the ribs for the thoracic vertebrae (White & Folkens 2005).

Main anatomical elements of the rib cage. (Image credit: Wikipedia 2011).

Rib Cage Anatomy, Terminology and Elements

The number of ribs present in the typical human skeleton is of 12 paired rib elements (a total of 24 altogether). Ribs project from proximal articulating facets with thoracic vertebrae, slant forward, and depending on the rib pair under consideration, articulate at the distal end with either the sternum, hard cartilage or ‘float’ freely (Jurmain et al 2011).  Ribs usually increase from size from rib 1 to rib 7, and decrease in size from rib 7 to rib 12 (White & Folkens 2005: 185).

Posterior view of ribs and their articulating vertebrae partners. (Image credit: Wikipedia 2011).

The Upper 7 ribs on each side of the cage connect distally directly to the sternum via cartilage, whilst the 8th, 9th and 10th ribs connect indirectly to the sternum.  The last 2 ribs are often called ‘floating’ ribs because they have ‘short cartilaginous ends that lie free in sides of the body wall’ (White & Folkens 2005: 181).

The basic landmark anatomy of a rib includes the head, neck, tubercle which articulates with the thoracic vertebrae & the long shaft of the rib.  In the picture below the head of the ribs are medial whilst the sternal ends are lateral.  The side that is superior is called the cranial edge, whilst the inferior is called the caudal edge.  It can be fairly easy to side a loose or partial rib as the Cranial edge is fairly thicker and blunter when compared to the grooved and sharp caudal edge (White & Folkens 2005: 192).

The rib cage laid out from 1st to 12th ribs, note the size and shape morphology. Occasionally an individual will have only 11 paired ribs or may have an extra pair, this is natural variation. (Image credit: Shutterstock).

Distinctive Rib Cage Elements

  • The 1st rib is most unusual and can usually be identified the easiest.  It is particularly blunt, broad and thick, as well as this it has no caudal groove (Roberts & Manchester 2010).
  • The 2nd rib serves as an intermediary to the 1st and 3-9th more regular ribs.  It has a large tuberosity for the serrator anterior muscle half way along its length (White & Folkens 2005: 187).
  • The 11th rib lacks a tubercle and the sternal end is often pointed.
  • The 12th rib is shorter then the 11th rib and may be even shorter then the 1st rib.  It lacks the angle and costal groove, and is often easy identifiable (May 1999).

Sternum

As stated the sternum is made of 3 individual bones, those of the manubrium, corpus sterni and the Xiphiod Process.  As made clear by the diagrams below, there are 7 facets located laterally for the anterior of the ‘true’ ribs alongside the corpus sterni and manubrium.  The sternum is composed of these three elements in adulthood but develops from 6 segments (White & Folkens 2005: 181).

The manubrium is the thickest and squarest part of the sternum bones and should be easily identifiable as such.  At the superior corners there are clavicular notches located, which articulates with the right and left clavicles.  The clavicles and scapula help to form the shoulder girdle and will be discussed in the next post.

The three individual elements of the sternum, with the manubrium (proximal), corpus sterni (centre) and xihoid process (distal) highlighted. (Image credit: Wikipedia 2011).

Lateral view of sternum elements with the individual rib facets highlighted. (Image credit: Wikipedia 2011).

The corpus sterni is rather thin in comparison to the manubrium, and it is often said to be ‘bladelike’.  Again, costal notches are present as seen in the above picture.  They cater for ribs 2-7 (Mays 1999).

The xiphoid process can be found inferior to the corpus sterni but, depending on the age of the person involved, may not be found in archaeological samples.  The process shares the seventh costal notch.  This bone is often highly variable in shape, and is late to ossify (White & Folkens 2005: 184).

A Pre-contact Peruvian Case Study

The site of Pacatnamu, in the Jequetepeque River valley on the northern Peru coast, provides a site where mutilated human remains and contextual information has been unearthed (Larsen 1997: 137).  At this Moche site (100-800 AD), evidence has been found of executed captives who were thrown into a trench at the bottom of an entrance to a ceremonial precinct (Verno 2008: 1050).  The skeletal group found & studied was composed of 14 adolescent and young adult males, who were recovered from 3 superimposed layers at the site.  The superimposed layers were indicative of 3 distinct burial episodes (Larsen 1997: 137).  From the evidence on the skeletal elements, it seems that weathering took place after death but before burial.  The evidence is backed up by the palaeoenvironmental remains of the presence of the pupal cases of muscoid flies (Verano 1986).

Pacatnamu mass burial archaeological site and the second layer (Image credit: Verano 2008).

It seems that the display of the decomposing bodies, together with a lack of a proper burial, was clearly intentional.  In the topmost layer of the burial episodes, multiple stab wounds were found on both the vertebrae and rib elements.  This pattern is broken by the bottom and middle layer where the pattern is more towards decapitation or throat slashing as evidence by cutmarks on the cervical vertebrae (Larsen 1997: 137).  Of particular interest is the evidence of five individuals from the middle and lower deposits that have bisected manubriums with evidence of fractured ribs, which is suggestive of the chest cavity being opened forcibly (Verano 1986).

Larsen (1997: 137) remarks that on the ‘basis of the age distribution, sex, and evidence of healed and unhealed injuries (rib fractures, depressed cranial fractures), Verano (1986) speculates that they were war prisoners’.   The conclusion is well supported from the cultural representations in the art and architecture of the Moche culture.  Many cultures throughout the world made, and continue to make, sacrifices of various kinds; in particular it is thought that for pre-contact South American cultures human sacrifice represented ‘the most precious form of sacrifices, and seems to have been reserved for particularly important rituals and events’ (Verano 2008: 1056).  It has also been noted that the capture and killing of enemies was a common practise in communities in pre-contact South America.  Such killings can also incur within ritual presentations and displays.  There are many such examples throughout South American, and indeed throughout the Americas (Teotihuacan, Punta Lobos, Sipan) (Verano 1986).  A careful consideration through the integrated studies of the archaeological sites, bioarchaeological study of the human material, together with careful ethnographic comparisons, can help to understand the processes and results of human sacrifice in South American cultures.

Further Information

Bibliography:

Jurmain, R. Kilgore, L. & Trevathan, W.  2011. Essentials of Physical Anthropology International Edition. London: Wadworth.

Larsen, C. 1997. Bioarchaeology: Interpreting Behaviour From The Human Skeleton. Cambridge: Cambridge University Press.

Mays, S. 1999. The Archaeology of Human Bones. Glasgow: Bell & Bain Ltd.

Roberts, C. & Manchester, K. 2010. The Archaeology of Disease Third Edition. Stroud: The History Press.

Verano, J. W. 1986. ‘A Mass Burial of Mutilated Individuals at Pacatnamu‘. In C. B. Donnan & G. A. Cock. (eds.) The Pacatnamu Papers. 1. pp.117-138. Los Angeles: Museum of Cultural History, University of California.

Verano, J. W. 2008. ‘Trophy Head-Taking and Human Sacrifice in Andean South America. In H. Silvermann & W. Isbell.(ed.) Handbook of South American Archaeology. pp.1045-1058. Los Angeles: Springer.

White, T. & Folkens, P. 2005. The Human Bone Manual. London: Elsevier Academic Press.