The purpose of this study is to perform a detailed morphological analysis of the changes that occur at the attachment sites of muscles, tendons, and ligaments on the radius. We consider the osteological, anatomical, and pathological aspects in detail, devising a visual standard for ranking the development of osseous expression at each attachment. We also discuss the etiology, particularly through focus on the relationship with the activity and age variables. In a sample of 148 radii from archeological and contemporary samples, 11 osteological sites were analyzed in each specimen. The osteological sites included nine muscular attachments, the attachment of the interosseous membrane, and the groove of the extensor pollicis longus tendon. The results show that mechanical loading is the main cause of different types of markings appearing and developing on the bone surface. Furthermore, there is a relationship between the osteological appearance of enthesis and its morphological type. It is possible to grade osteological appearance with a visual reference method that establishes an identifiable threshold for each grade and eliminates relying completely on observer experience. This methodology is applicable to the field of physical anthropology and to its forensic subfield, identifying individuals by attributing to them specific work or given activities through the use of skeletal remains. Anat Rec Part A, 288A: 794 -805, 2006.
Despite considerable literature on the functional anatomy of the hominoid upper limb, there are no quantitative approaches relating to bone design and the resulting muscular-activity enhancement. The purpose of this study is to quantitatively analyze the relationship between the rotational efficiency of the pronator teres muscle and the design of the skeletal structures on which it acts. Using conventional scan images of a human forearm for three rotational positions, this study develops an original biomechanical model that defines rotational efficiency as a mathematical function expressing a geometrical relationship between the origin and insertion muscular sites. The results show that this parameter varies throughout the entire pronation range, being maximal when the forearm lies around its functional position. Moreover, the rotational-efficiency formula allows us to demonstrate, by several simulation conditions, that an improvement in pronation efficiency is derived from a large shaft radius curvature, a large humeral medial epicondyle, and a more proximal pronator teres radial attachment. The fact that forearm pronation efficiency can be inferred, even quantified, throughout the entire rotational range, by applying the biomechanical model developed here allows us to undertake anatomical approaches in the field of Evolutionary Anthropology, to interpret more precisely how skeletal design is related to upper-limb function in extant and fossil primate taxa.
Timing bone fractures is one of the main tasks of a forensic anthropologist, but still an uncertain diagnostic. In the literature, there are many macroscopic methods to distinguish perimortem from postmortem fractures, based on the distinct structural and mechanical properties of fresh and dry bones. However, this differentiation is still challenging, in particular when the bones are fragmented or still exhibit fresh properties. Although histologic analysis is often used as a complementary diagnostic tool in forensic pathology, its application in the evaluation of bone fractures is uncommon. The aim of this study was to investigate whether fractures of fresh bones reveal a distinct microcracking pattern compared to fractures of dry bones, in order to optimise the fracture timing. To this purpose, we histologically analysed perimortem and postmortem fractures in human humeri. The fresh bones were retrieved from traumatic autopsy cases, and the dry bones from donors which were experimentally fractured. Our results showed that the highest density and length of microcracks (MCKs) were found in the interstitial area of dry fractured bones, which may be considered a marker of postmortem damage. In fresh fractured bones, we generally observed a lower density of MCKs, but a higher proportion of osteonal MCKs, which may be considered a marker of perimortem trauma. In summary, the results of our exploratory study suggest that changes in intrinsic bone factors (mineral/organic components) result in a different microcracking pattern that can be used in fracture timing.
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