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Four of A Kind: Body Focused Books

7 Dec

There has been a recent spate of publications that will interest the wide variety of professions that study and work with the human body, and a few that will be of major interest to those in the bioarchaeological and anthropological fields who study both the physical remains of the body and the cultural context that these bodies lived, or live, in.  With the annual Christmas celebrations a matter of weeks away, I’d thought I’d highlight a few publications that could potentially be perfect presents for friends and family members who are interested in the human body, from anatomical inspection to the personal introspection of what my body, and yours, can inform us of ourselves and the world around us…

bodybooks

Cover shots of the four books discussed below.

Adventures in Human Being: A Grand Tour from the Cranium to the Calcaneum by Gavin Francis. London: Profile Books (in association with the Wellcome Collection). 

Having previously read Francis’s book on being a doctor in Antarctica and knowing that he has accrued a wealth of knowledge and experience of treating the body from a medical viewpoint in a wide variety of countries, I was intrigued to see this new publication by him, which focuses on different sections of the body as a jumping off point for the essays in this collection.  I’d recently read Tiffany Watt Smith’s The Book of Human Emotions: An Encyclopedia from Anger to Wanderlust (which, coincidentally, is also published by Profile Books and the Wellcome Collection), which introduces over 150 different human emotions in an exciting combination of psychological, anthropological, historical and etymological mini essays on the human condition.  It was a thoughtful book and made me wonder about how we approach the body in bioarchaeology, whether our lexical terminology isolates and intimidates, frustrates and alienates those who we seek to engage and educate.  The Book of Human Emotions succinctly highlighted what we think is the universal, the standard charge sheet of emotions (anger, fear, joy, love, etc.) that can be found in cultures across the world, is actually not quite the case or clear-cut, and that they can be expressed and felt in different ways.  Francis’s book, I think, will also offer something as equally as thought-provoking.  Known not just for his medical expertise but also for the humanity of his writing, Francis’s exploration of the body, as a story we can each call our own, delves into the medical, philosophical and literature worlds to uncover the inner workings of the human body, in good health, in illness and in death.

Crucial Interventions: An Illustrated Treatise on the Principles and Practices of Nineteenth-Century Surgery by Richard Barnett. London: Thames & Hudson (in association with the Wellcome Collection).

I came across the above book purely by chance whilst out browsing bookstores in York recently and I have to say it is now on my festive wish list.  The medical historian Richard Barnett introduces a publication detailing the knowledge and variety of surgical practices available to the 19th century surgeon, focused largely on the presentation of the technical drawings produced in the era as a precise method for communicating the advancements made in a variety of treatments.  The publication introduces some of the earliest effective surgical techniques for dealing with devastating facial and limb injuries, either from disease processes, traumatic incidents or the outcomes of warfare, and documents the procedures used in re-configuring the body to alleviate the pain and the disfigurement suffered from such injuries and traumas.  It may not be for the faint of heart, but I could see that some modern-day surgeons may be interested to learn of past techniques, the tools and resources that they had, and the importance of always improving and building upon the innovations of the past.

Bioarchaeology: An integrated Approach to Working with Human Remains by Debra L. Martin, Ryan P. Harrod & Ventura R. Pérez. New York: Springer.

For any undergraduate or postgraduate student of archaeology that has a burgeoning interest in biarchaeology as a profession, I’d heavily encourage them (and the department) to get a copy of Bioarchaeology: An Integrated Approach to Working with Human Remains by Martin, et al.  The volume concisely introduces the discipline and outlines the background to it, the theories and methodologies that have informed the theoretical and practical application of bioarchaeology, the current state of play with regards to legal and ethical frameworks, and, finally, the impact and the importance of bioarchaeology as a whole.  The volume also uses invigorating case studies to elucidate the methods of best practice and the impact of the points made throughout the volume.  It is an excellent guide to the discipline and well worth purchasing as a reference book.  Furthermore the volume is now out in paperback and it is very handy to have in your backpack, partly as a one stop reference for any theories or methodologies currently used in bioarchaeology but also as a pertinent remainder of the value of what we do as bioarchaeologists and why we do it.

Theory and Practice in the Bioarchaeology of Care by Lorna Tilley. New York: Springer (Hardback only at the moment).

The post before this one has already detailed the aim and scope of this publication but I feel it is worth highlighting here again.  The bioarchaeology of care, and the associated online Index of Care application, aims to provide the bioarchaeologists with the tools for a case study framework for identifying the likelihood of care provision in the archaeological record by providing four stages of analysis in any individual skeleton exhibiting severe physical impairment, as a result of a disease process or acquired trauma.  The methodology takes in the importance of palaeopathology (the identification and diagnosis, where possible, of pathological disease processes in skeletal remains which has a firm basis in modern clinical data) but also the archaeological, cultural, geographic and economic contexts, to examine whether receipt of care is evidenced.  In the publication Tilley documents and investigates a number of prehistoric case studies, ranging from the Upper Palaeolithic to the Neolithic, and determines the likelihood of care and the type of care that was needed for the individuals under study to survive to their age at death.  The theoretical background and implications, alongside the ethical grounding of the methodology and the concerns in terminology, are also documented at length.  Perhaps most importantly, this is a methodology that is open to improvement and to the use within current and future research projects.  It is also a method that can be used first hand when examining skeletal remains or from the literature itself (where available to a good enough standard).

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The above publications are, to me, some of the most interesting that I have seen recently, but I am always on the look out for more.  Please note that the average costs of the books above are within the £10.00-£20.00 range, but prices will vary significantly.  The hardback academic publications can be quite expensive (+ £70), however once the volume is out in paperback the price tends to fall steeply.  If you can recommend anything please let me know in the comments below.

And Finally a Stocking Filler…

The University of Durham is playing host to a one day conference entitled Little Lives, focusing on new perspectives on the bioarchaeology of children, both their life course and their health, for the very fair price of £10.00 on the 30th of January 2016.  The Facebook group for the conference can be found here.  Alternatively contact the conference organizers via the Durham University webpage here to secure a place (something I must do soon!).

littlelivesdurham16

Please note that the call for papers date has now passed and that the conference program has now been finalized.

Further Information

  • The Wellcome Trust, which helps operate the Wellcome Collection, is an independent global charity foundation dedicated to improving health by funding biomedical research and medical education.  The charity also has a keen focus on the medical humanities and social sciences, and it recognizes the importance of running educational workshops, programs and outreach events.  Find out more information on the charity here.
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Bone Quiz: Osteology From Outer Space

23 Sep

I saw this pop up earlier on my friend Charles Hay’s social feed and it immediately clicked as I saw osteology in space.  It’s actually the comet 67P/Churyumov-Gerasimenko (bit of a mouthful) rather than a skeletal element lost in space, but can the readers of this blog identify what I think I see below?  If you can, let me know what you think it is in the comment section below and, for bonus points, tell me how these generally differ from others found in the body.  You may have to squint a bit and remember that the distal parts of this element can vary somewhat in shape…

This comet is currently the focus of attention of the space probe Rosetta’s lander, Philae, as the European Space Agency hopes to soon land on and investigate this intriguing piece of rock.  The comet is currently (in the words of Col. Chris Hadfield, or at least his FB profile) spewing out water, methane, methanol, CO2 and ammonia, a mix that is the stuff of life (but probably quite smelly).  Keep up to date here as the ESA attempts to land Philae on the comet in early November.

spacethumb

A recent image sent back by the ESA Rosetta probe of the comet 67P/Churyumov-Gerasimenko. Image credit: ESA/Rosetta/NavCam/Emily Lakdawalla.

I’ll put the answer up in a few days or so, so please leave a comment if you think you know what this is!

Bone quizzes are part of a staple diet that anybody learning human osteology at university takes part in regularly.  They are often timed tests (normally a minute or so) where you can be asked to identify a fragment of bone, side it and name any anatomical landmarks that are highlighted on the element.  It is a great way to learn your skeletal anatomy, especially before heading into an archaeological excavation where bones can often be found in unexpected places and isolated from other elements.

Further Information

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Bone Quiz Answer

This quiz was probably picked bit too arcane an object for a bone quiz, but the answer can be found below.  Note in the comment’s section JB and Keneiloe’s answers for different views!

Image credit: source.

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 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.

knee joint

The complex knee joint and associated ligaments that keep the joint stable. Image credit: The Healthy Dancer.

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 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.

Skeletal Series Part 4: The Human Spine

30 Apr

As we started with the skull in this series of posts, we shall continue with the axial skeleton, and discuss the vertebral column (or spine) in the human skeleton.  The human spine consists of vertebrae that help support the back muscles, protect the spinal column, and provides the rod function for the axial skeleton (Mays 1999).  We’ll firstly discuss the moveable vertebrae, then move onto the hyoid, sacrum and coccyx elements.

On a personal note, I have difficulty with identifying vertebrae and reconfiguring them in the right order.  This is something I’m hoping to improve soon!  Meantime, here is a short guide…

As the basic excavation methods have already been discussed in the previous post, we will miss them out here.  Once again, care should be taken with handling, and it is unlikely all the elements would survive.  The hyoid bone is particularly liable to be missing or broken as it is a fairly small and fragile bone (Larsen 1997).

Vertebrae Anatomy, Terminology and Elements

The human spine consists of 33 vertebrae in total; 24 are considered to be part of the upper spine, whilst the other 11 are found in the Sacrum & Coccyx (discussed below).  The 24 vertebrae can be split into three separate groups based on morphology, spinal curvature and position; those of the Cervical, Thoracic & Lumbar vertebrae (White & Folkens 2005).  The vertebrae are often referred to by their first distinction, and by the number in that area.  So the second cervical vertebrae is referred to as the C2 etc.

The main bone landmark features of a typical vertebra are presented in the diagram below.  Please note that there are variations depending on the class of vertebrae under discussion.

Typical bone landmarks found on vertebrae and anatomical information (Eckalbar et al 2012. Scoliosis and Segmentation Defects of The Vertebrae. Developmental Biology. 1 (3): 402.)

The vertebrae in these groups are typically found as below (proximal to distal):

Cervical: 7 Vertebrae present.  The normal cervical vertebrae include interlocking vertebral bodies, with saddle shaped superior and inferior surfaces; alongside this the canal (see below) is triangular and of a similar size to the vertebral body (Mays 1999).  The spinous process are shorter than in thoracic and not as massive as lumbar vertebrae processes (White & Folkens 2005: 163).

Thoracic: 12 Vertebrae present.  The elements in this section of spine again increase in body size (vertebral body).  Each thoracic element articulates with a pair of ribs in the human skeleton.  It has been noted that ‘upper thoracic bodies are roughly triangular in a superior outline whilst the lower thoracic vertebral bodies are more circular’ (White & Folkens 2005: 170).  The vertebrae canal (or arch which the spinal column runs through posteriorly) are smaller relative to the vertebral body, and importantly, more circular than in cervical vertebrae (Waldron 2009).

Lumbar: 5 Vertebrae present.   Finally the vertebral bodies of the lumbar vertebrae once again increase in size from superior to inferior (as all vertebrae do).  They are the largest of all the unfused vertebrae, and should be easily identifiable by their size and features (larger spinous process, vertebral bodies, & smaller transverse process and lumbar arches) (White & Folkens 2005: 178).

It must be remembered that due to variation, an added or missing vertebra, is a possibility.  Between the individual vertebrae bones are intervetebral discs present.  In life, they help to provide movement between bones and act as ligaments.

Cervical, Thoracic & Lumbar Vertebrae & Anatomical Features.

As discussed above, there are three vertebrae types, as seen in the diagram above and below.  Important changes in the morphology and shape of these elements can be noted, thus each part can be ascertained to the differing thirds of the spine (White & Folkens 2005).  As it can be seen from the diagram below, the thoracic & lumbar vertebrae have a much more developed Vertebral Body (cementum in other animals), alongside a much more elongated Spinous Process.

Differences In Body Shape for Cervical (C4), Thoracic (T6) & Lumbar (L2) Vertebrae.

Distinctive Elements

The Atlas and Axis Vertebrae (diagram below), the first and second cervical vertebrae, are the most distinctive in terms of size and morphology.  The Atlas bone (C1) lies between the cranium (connecting with the condyles of the occipital bone) and the Axis  vertebrae (C2).  The atlas lacks a ‘vertebral body, a spinous process and has no articular disks either superior or inferior to it’ (White & Folkens 2005: 163).  The Axis bone also lacks a typical vertebral body.  It’s most distinctive feature is the odontoid peg, as seen in the diagram below.  This allows the head to rotate, moving the atlas about the odontoid peg of the axis bone (White & Folkens 2005: 169).

Features Of The Atlas (C1) & (C2) Axis Vertebrae

Transitional vertebrae include the sixth cervical vertebrae, which has a larger cementum (body) and a spinous process resembling a thoracic vertebrae.  The twelfth thoracic vertebrae resembles the eleventh vertebrae but the inferior articular facets assume the lumbar pattern rather than the typical thoracic pattern (White & Folkens 2005: 170).

The Hyoid bone (diagram below) is the located in the neck, immediately above the Adams apple on the anterior surface of the neck.  it is the only bone in the human body that does not articulate with any other bone whatsoever.  It consists of the body, the lesser horns and greater horns, as can be discerned in the diagram below (White & Folkens 2005: 155).  Unfortunately, it is often broken (fractured) during strangulation, and can be used as key indicator in murder cases.

Details of The Hyoid Bone

The Sacrum (diagram below) consists of five fused vertebrae in a wedge like shape at the bottom of the vertebral column.  These fuse in adolescents, and can consists of between four to six segments, although five is the normal average.  To both lateral sides are the pelvic bones (Os Coxa), whilst inferiorly lies the coccyx.

The Coccyx (diagram below) articulates distally to the Sacrum, and consists of 3 to 5 fused elements (variation is common).  It is the vestigial tail, and highly variable in shape.  In later life, the Coccyx may fuse to the Sacrum.  As with the above bone, the coccyx decreases in size inferiorly (White & Folkens 2005: 245).

Sacrum Terminology

Discussion of Osteoarthritis

As biped hominids, homo sapiens are at the mercy of numerous back problems.  The wear and tear, stresses and strains, that the vertebrae have to take are often manifested through various disease & maladies (Jurmain et al 2010).  Specifically, there is an increased susceptibility  in spinal joint disease.  Osteoarthritis is one such example, (OA) presenting in vertebrae that often occurs as a direct response to spinal stress (Roberts & Manchester 2010: 139).  The spine is recognised as ‘exhibiting a backward curve in the chest or thoracic region and a forward curve in the lumbar and cervical regions’; which lead to the C5, T8 & L4 vertebrae as being the most affected by joint disease (Roberts & Manchester 2010: 139).

These points are the areas of maximum and minimum stress, and this is seen as the variation in the frequency of OA in the spinal column.  As Waldron (2009: 27-30) states, ‘osteoarthritis is primarily a disease of the articular cartilage which breaks down as the disease progresses’.  The incipient factor is the enzymatic breakdown of the cartilage matrix, and affects the bone in the following ways.

The five main steps are outlined below:

1.  ‘Formation of new bone (after mixed signals from enzymes) around the margins of the joint; often called marginal ostephytes.

2.  Formation of new bone on the joint surface due to the vascularisation of the subchondral bone.

3. Pitting on the joint surface manifested as a series of holes on the joint surface.

4.  Changes in the normal contour of the joint, often widening and flattening of he contour.

5.  The production of eburnation, a highly polished area on the joint surface, usually sharply demarcated from the non-eburnated surface.  This area is sometimes grooved towards the motion and direction of the joint; presumably due to debris or crystals between the two articulating surfaces’ (Waldron 2009: 27-29).

Eburnation On The ‘Peg’ of the Axis Vertebrae (Shiny & Smooth Wearing)

Factors that are known to be important as precipitates to OA include age, race, sex, genetics, obesity, trauma and most importantly, movement itself.  Age is particularly important, as at the older standard range of human health there is scarcely anyone left with normal joints (Roberts & Manchester 2010, Waldron 2009).  An example of OA occurring in populations will now be discussed.  Lovell (1994) discuss a site in Pakistan, dating from 4000-5000 years ago (Bronze Age), where a pattern of OA was seen in the population.  The disease was noted as mechanical in nature (as normal), but focused on the cervical vertebrae.  This may be a reflection of activity in which the people carried heavy loads upon their heads (Roberts & Manchester 2010: 141).

The excavation of medieval rural site of Wharram Percy, in North Yorkshire, uncovered a large series population (May 1999).  Examination of features on the spinal column indicate OA was prevalent in the population at around 55 per cent for males and 39 per cent for females.  Because the site was rural in nature, and had indication of being used as an agricultural centre, it was identified that this population had developed OA through their lifestyle choices (Roberts & Manchester 2010: 143).  Useful as these sites, and features are, it should be reminded that ‘spinal joint disease was not the ideal part of the skeleton to observe as a marker of activity-related stress’ (Roberts & Manchester 2010: 143).

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.

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 1: Bone Variation & Biomechanics

10 Apr

In the following series of blog posts I aim to cover each of the main skeletal elements.  Each post will have a single focus on a bony element, from the skull down to the bones of the foot.  Firstly though we must deal with the variation that human osteologists and bioarchaeologists will see in individual skeletons, and in a population series.  It is both useful and informative to learn the differences and the effects caused by the 4 main variation factors in the morphology of human bones.  As it is by ascertaining the degree of influences that the variation factors can cause that we can begin to understand the individual, and the skeletal series of a population, in a more informative and considered way.  The second part of this entry will focus on the basics of biomechanics, and the influences certain lifeways can have on bone.

The basic biology of bones was previously discussed in this post here, and of teeth here.  Bone in its natural state must be recognised as a changing living organism throughout life that responds to stress, both nutritional and mechanical, and remodels accordingly.  It is also must be remembered that bone is a composite material, and is able to heal itself.

Variation 1 : Ontogeny

Ontogeny is simply growth and development of an organism, in this case Homo sapiens.  The archaeological record of skeleton remains include unborn individuals right through to individuals in their 70th year and beyond.  Typically there are 7 classification groups of human age groups.  They run from Fetus (before birth), Infant (0-3 years), Child (3-12 years), Adolescent (12-20 years), Young Adult (20-35 years), Middle Adult (35-50 years), and Old Adult (50+ years) (White & Folkens 2005: 364).  Differences in bone structure, and in the growth of different bone elements often manifest themselves in changes in size and shape.

Adult with Two Juvenile Remains, From Southern Sahara

Basic Growth Profile for Homo Sapiens, Notice the Large Cranium and the Way the Body Catches Up.

Variation 2: Sexual Dimorphism

Humans are sexually dimorphic, that is there are differences between the female and male body size.  Although not as distinct between our cousins such as the gorillas, female human skeletal remains are relatively smaller in both bones and teeth size (Jurmain et a 2010).  Such skeletal variation is also manifest in the requirement of reproductive functions in the female skeleton, thus we are also often able to tell sex from skeletal remains (White & Folkens 2005: 32).

Generalised Male:Female Sexual Dimorphism

Variation 3: Idiosyncractic Differences

The idiosyncratic  (or individual) differences found in skeletons are simply natural variations, in the understanding that every body is different, and rarely are people exactly the same (identical twins excluded).  Idiosyncratic differences in bone affect the size and shape of the bone, and the topography of the bone surface.  Again, such variation is very common in human skeletal remains (White & Folkens 2005: 32).

Disarticulated human bone from the site of Armana, ancient Egypt.

Variation 4: Geographic or Population-Based

As White & Folkens point out ‘different human groups can differ in many skeletal and dental characteristics’ (2005: 32).  Thus this geographic variation can be employed to assess population affinities between skeletal series.  This trait can be quite useful in determining commingling of certain populations in prehistoric skeletal series as certain environmental and genetic traits can be passed on.

Biomechanic Basics

So these are the four main variations we should be aware of when we are looking and studying individual skeletons or a series of a population.  By considering these four main variations we can study the individual’s life pathway alongside other lines of investigation.  What we must also take into account next are the basics of biomechanics.  Biomechanics is the application of engineering principles to biological materials, whilst remembering that bone can remodel and change according to pressures put upon the bone.  As Larsen states that ‘the density of bone tissue differs within the skeleton and within individual bones in response to the varying mechanical demands’ (1997: 197).  It must be remembered that the response of human bone to ‘increased loading is in the distribution of bone (geometric) rather than density or any other intrinsic material property of bone’ (Larsen 1997: 197).

Importantly it is noted that Human bone is anisotropic, meaning its mechanical properties vary according to the direction of the load.  Importantly, Wolff’s Law highlights how bone replaces itself in the direction of functional demand.  A classic example of the remodelling capabilities of bone is that of the tennis player who has thicker cortical bone in their dominant arm.  This manifests itself in thicker cortical bone alongside hypertrophy of the muscle attachment sites.  One study carried out found that ‘males have a 35% increase in the cortical bone in the distal humerus of the playing arm vs the non-playing arm’, helping to exemplify Wolff’s Law (Larsen 1997: 196).  That study was an example of bilateral asymmetry humeral loading.  Alongside, it is the action of the main forces acting on human bone that help to change the bone, these  include a) compression, b) tension, c) shear, d) torsion & E) compression + tension+ bending.

Wolff’s law states that healthy load bearing bone (LBB) responds to strain by ‘placing or displacing themselves (at a mechanical level) in the direction of the functional pressure, & increase or decrease their mass to reflect the amount of functional pressure’, often muscular strain and/or weight bearing pressures (Mays 1999: 3).  As a part of this Frost (2004: 3) argues that the ‘mechanostat’, a tissue level negative feedback system, involves ‘two thresholds that make a bone’s strains determine its strength by switching on and off the biologic mechanisms that increase or decrease its strength’.  However, Skerry (2006: 123) has argued that there are many ‘mechanostats’ operating on the LBB and that different elements throughout the skeleton require different strain magnitudes for maintenance. Furthermore Skerry (2006: 126) also notes that differences are apparent between the sexes, and that genetic constitution, concomitant disease, exercise & activity patterns must be considered.

A recent article has also highlighted how the femoral neck width of obese people changes to accommodate the added weight.  In this case the width of the femoral neck has increased to dissipate weight throughout the bony area by increasing surface area and strength through redistribution of bone.  This is an example of active bone remodelling adapting to changes that the person has gone through in life.

An archaeological example of the above will now be taken from Larsen 1997.  ‘In the Pickwick Basin of northwestern Alabama, analysis carried out on both femora and humeri cross-sectional geometry has helped to reveal a number of differences between earlier Archaic Period hunter-gatherers and later Mississippian Period agriculturalists‘ (1997: 213).  From the femora measurements it seems that the both female and male agriculturalists had a greater bone strength, whilst analysis of male humeri shows little difference between the two series.  This has helped to show that activity levels increased for males but only in the lower limbs, as evidenced by the cross-section geometry.  However, for females of both time periods both humeri and femora strengths increased.  The article cited in Larsen (1997), Bridge 1991b, findings indicate that changes are from a greater range of activity undertaken by females than males.  With palaeopathological signs of osteoarthritis, it is concluded that the shift to food production,in particular maize production, may have had a relatively greater impact physically on women in this setting.

The next post will focus on ethics in human osteology, and from there we will consider each of the anatomical skeletal elements in context of their relative limb.

Bibliography

Frost, H. M. 2004. (A 2003). Update on Bone Physiology and Wolff’s law for Clinicians. Angle Orthodontist.  February 2004. 74 (1): 1-15.

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.

Skerry, T. M. 2006. One Mechanostat or Many? Modifications of the Site-Specific Response of Bone to Mechanical Loading by Nature and Nurture. Journal of Musculoskeletal & Neuronal Interaction. 6 : 122-127. (Open Access).

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