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How changes in anatomy affect joint biomechanics can be studied using musculoskeletal modelling, making it a valuable tool to explore joint function in healthy and pathological joints. However, gathering the anatomical, geometrical and physiological data necessary to create a model can be challenging. Very few integrated datasets exist and even less raw data is openly available to create new models. Therefore, the goal of the present study is to create an integrated digital forearm and make the raw data available via an open-access database. An un-embalmed cadaveric arm was digitized using 7T MRI and CT scans. 3D geometrical models of bones, cartilage, muscle and muscle pathways were created. After MRI and CT scanning, physiological muscle parameters (e.g. muscle volume, mass, length, pennation angle, physiological cross-sectional area, tendon length) were obtained via detailed dissection. After dissection, muscle biopsies were fixated and confocal microscopy was used to visualize and measure sarcomere lengths. This study provides an integrated anatomical dataset on which complete and accurate musculoskeletal models of the hand can be based. By creating a 3D digital human forearm, including all relevant anatomical parameters, a more realistic musculoskeletal model can be created. Furthermore, open access to the anatomical dataset makes it possible for other researchers to use these data in the development of a musculoskeletal model of the hand. ispartof: Journal of Anatomy vol:233 issue:5 pages:557-566 ispartof: location:England status: published

The human hand is well known for its unique dexterity which is largely facilitated by a highly mobile, long and powerful thumb that enables both tool manufacturing and use, a key component of human evolution. The bonobo (Pan paniscus), the closest extant relative to modern humans together with the chimpanzee (Pan troglodytes), also possesses good manipulative capabilities but with a lower level of dexterity compared with modern humans. Despite the close phylogenetic relationship between bonobos and humans, detailed quantitative data of the bonobo forelimb musculature remains largely lacking. To understand how morphology may influence dexterity, we investigated the functional anatomy of the bonobo hand using a unique sample of eight bonobo cadavers, along with one chimpanzee and one human (Homo sapiens) cadaver. We performed detailed dissections of unembalmed specimens to collect quantitative datasets of the extrinsic and intrinsic hand musculature, in addition to qualitative descriptions of the forelimb muscle configurations, allowing estimation of force-generating capacities for each functional group. Furthermore, we used medical imaging to quantify the articular surface of the trapeziometacarpal joint to estimate the intra-articular pressure. Our results show that the force-generating capacity for most functional groups of the extrinsic and intrinsic hand muscles in bonobos is largely similar to that of humans, with differences in relative importance of the extensors and rotators. The bonobo thumb musculature has a lower force-generating capacity than observed in the human specimen, but the estimated maximal intra-articular pressure is higher in bonobos. Most importantly, bonobos show a higher degree of functional coupling between the muscles of the thumb, index and lateral fingers than observed in humans. It is conceivable that differentiation and individualization of the hand muscles rather than relative muscle development explain the higher level of dexterity of humans compared with that of bonobos. ispartof: Journal of Anatomy vol:233 issue:3 pages:328-340 ispartof: location:England status: published