Anatomical Specimens (anatomical + specimen)

Distribution by Scientific Domains

Selected Abstracts

The intertarsal joint of the ostrich (Struthio camelus): Anatomical examination and function of passive structures in locomotion

Nina U. Schaller
Abstract The ostrich (Struthio camelus) is the largest extant biped. Being flightless, it exhibits advanced cursorial abilities primarily evident in its characteristic speed and endurance. In addition to the active musculoskeletal complex, its powerful pelvic limbs incorporate passive structures wherein ligaments interact with joint surfaces, cartilage and other connective tissue in their course of motion. This arrangement may enable energy conservation by providing joint stabilisation, optimised limb segment orientation and automated positioning of ground contact elements independently of direct muscle control. The intertarsal joint is of particular interest considering its position near the mid-point of the extended limb and its exposure to high load during stance with significant inertial forces during swing phase. Functional-anatomical analysis of the dissected isolated joint describes the interaction of ligaments with intertarsal joint contours through the full motion cycle. Manual manipulation identified a passive engage-disengage mechanism (EDM) that establishes joint extension, provides bi-directional resistance prior to a transition point located at 115° and contributes to rapid intertarsal flexion at toe off and full extension prior to touch down. This effect was subsequently quantified by measurement of intertarsal joint moments in prepared anatomical specimens in a neutral horizontal position and axially-loaded vertical position. Correlation with kinematic analyses of walking and running ostriches confirms the contribution of the EDM in vivo. We hypothesise that the passive EDM operates in tandem with a stringently coupled multi-jointed muscle-tendon system to conserve the metabolic cost of locomotion in the ostrich, suggesting that a complete understanding of terrestrial locomotion across extinct and extant taxa must include functional consideration of the ligamentous system. [source]

If bone is the answer, then what is the question?

In the 19th century, several scientists attempted to relate bone trabecular morphology to its mechanical, load-bearing function. It was suggested that bone architecture was an answer to requirements of optimal stress transfer, pairing maximal strength to minimal weight, according to particular mathematical design rules. Using contemporary methods of analysis, stress transfer in bones was studied and compared with anatomical specimens, from which it was hypothesised that trabecular architecture is associated with stress trajectories. Others focused on the biological processes by which trabecular architectures are formed and on the question of how bone could maintain the relationship between external load and architecture in a variable functional environment. Wilhelm Roux introduced the principle of functional adaptation as a self-organising process based in the tissues. Julius Wolff, anatomist and orthopaedic surgeon, entwined these 3 issues in his book The Law of Bone Remodeling (translation), which set the stage for biomechanical research goals in our day. ,Wolff's Law' is a question rather than a law, asking for the requirements of structural optimisation. In this article, based on finite element analysis (FEA) results of stress transfer in bones, it is argued that it was the wrong question, putting us on the wrong foot. The maximal strength/minimal weight principle does not provide a rationale for architectural formation or adaptation; the similarity between trabecular orientation and stress trajectories is circumstantial, not causal. Based on computer simulations of bone remodelling as a regulatory process, governed by mechanical usage and orchestrated by osteocyte mechanosensitivity, it is shown that Roux's paradigm, conversely, is a realistic proposition. Put in a quantitative regulatory context, it can predict both trabecular formation and adaptation. Hence, trabecular architecture is not an answer to Wolff's question, in the sense of this article's title. There are no mathematical optimisation rules for bone architecture; there is just a biological regulatory process, producing a structure adapted to mechanical demands by the nature of its characteristics, adequate for evolutionary endurance. It is predicted that computer simulation of this process can help us to unravel its secrets. [source]

The celebrated écorchés of honoré Fragonard, part 1: The classical techniques of preparation of dry anatomical specimens in the 18th century

Christophe Degueurce
Abstract The écorchés that Honoré Fragonard created between 1766 and 1771 have miraculously survived the ravages of time due to a technique of preparation which Fragonard never revealed. The present paper and a subsequent article aim to explain the classical methods used by anatomists of the 18th century (Part 1) and to throw light on the details of Fragonard's method (Part 2). Anatomists of the 18th century who wished to preserve their dissections used a method of mummification, which has now fallen into disuse: drying after immersion in alcohol. This article explains the stages of the classical method utilized by French anatomists of the Age of Enlightenment. The cadaver was selected with care before the vascular system was injected with a colored mixture of wax, animal fat, and plant resins. The body was then dehydrated by immersion in a bath of alcohol, after which it was removed and positioned by means of a wooden framework, which held the body in the desired pose while the alcohol evaporated. The vessels were painted, and finally the body was varnished. Clin. Anat. 23:249,257, 2010. © 2010 Wiley-Liss, Inc. [source]

What did William Hunter know about bone?

Stuart W. McDonald
Abstract This article examines William Hunter's specimens on bone in the Anatomy Museum at the University of Glasgow. By referring to students' notes taken at Hunter's lectures and to the Manuscript Catalogue of his anatomical specimens, we attempt to answer the question, "What did William Hunter know about bone?" Hunter seems to have been particularly interested in the relationship between vascularisation and ossification and many of the specimens illustrate this. He provided his students with reasoned arguments on a number of issues: that the marrow serves as a fat store and not to produce synovial fluid or to keep bones supple; the periosteum serves as an attachment for tendons and ligaments; the rationale for the presence of epiphyses is not readily defined; that bones form by intramembranous and endochondral ossification and that, in the latter, cartilage is replaced by bone. William Hunter narrowly failed to realise that in long bones new bone is laid down by the periosteum and at the epiphysial plates, and is remodeled. These discoveries were to be made by his brother, John. Clin. Anat. 18:155,163, 2005. © 2005 Wiley-Liss, Inc. [source]

William Hunter's Gravid Uterus: The specimens and plates

N.A. McCulloch
Abstract William Hunter's collection of anatomical specimens of the pregnant uterus forms one of the finest displays in the Anatomy Museum at the University of Glasgow. We were interested to know which specimens in the Museum matched the plates in Hunter's The Anatomy of the Human Gravid Uterus Exhibited in Figures (1774). In our investigation we were greatly assisted by Teacher's Catalogue of the Anatomical and Pathological Preparations of Dr William Hunter (1900). Thirteen specimens in the Museum and one from the pathological collection at the Royal Infirmary are represented in Hunter's book. The specimens can be recognized in 25 of its illustrations. A further three specimens may correspond to figures but we could not prove this. With one possible exception, all the specimens matching plates noted in Teacher's catalogue remain in the Museum and one believed missing in Marshall's (1970) revision of the catalogue has been found. Clin. Anat. 15:253,262, 2002. © 2002 Wiley-Liss, Inc. [source]