Morphogenesis of the human palma arch using three‐dimensional geometric modeling

Abstract

The hand goes through complex morphological modifications during embryogenesis. The goal of this study was to use geometric modeling to study the morphometric modifications of the palmar arch. Five embryos were used for the study (sizes: 15, 17, 23, 30, and 44 mm). After digitalization of histologic sections (Sony DXC-930P 3CCD camera, Leica Qwin) and segmentation of the metacarpal cartilaginous matrices (Winsurf 4.3 software), geometric modeling and calculations were performed using MSC.Patran 2005r2 software. Correlations (r > 0.99) were found between embryo size and metacarpal volume, metacarpal surface, and the surface of the modeled palmar arch. The growth of the palmar arch is nonhomothetic. Significant reduction (P = 0.05) in the divergence of the 2nd, 3rd, 4th, and 5th metacarpals was observed. Deepening of the palmar arch is correlated with embryo size and age (r > 0.99). Geometric modeling allows 3D rendering of histologic sections and thus quantitative description of the morphogenesis. The results of this study support the hypothesis that opposition of the thumb in correlation with deepening of the palmar arch appears early in embryological development. It constitutes a specific morphological characteristic that appears very early in the human phylum. The fact that the human thumb is naturally in opposition in the resting position is a consequence of this morphogenesis. The thumb's resting position has received little attention in clinical settings and should be considered as the reference position for biomechanical analysis of the thumb column.

Design and Development of a Wearable Exoskeleton System for Stroke Rehabilitation

“…As shown in Figure 1, every MCP has two DOFs, while every PIP, DIP, and IP have one DOF, making up a total of 19 DOFs in each hand. The large number of DOFs makes any assistive device design for the hand quite challenging [36] and is made even more difficult by the complex structure of the bones of the hand: there is a great anatomical variation in the shape and dimensions of individual bones [37], the location on the device where the finger joint aligns is hard to accommodate to everyone's hand size; for example, for the PIP, because of the variation in finger bone length, some may fall near the proximal phalanx while others fall near the distal, and the same scenario also applies to the DIP; while the MCP may not have this problem, because of the variation in palm width, the thumb is often either compressed or too far out and therefore often excluded from exoskeleton designs, making it hard to develop an exoskeleton for rehabilitation that can accommodate a large number of people.…”

Design-validation of a hand exoskeleton using musculoskeletal modeling

“…to rely on fully digital models to guide and validate the design of an exoskeleton, with a focus on the hand. The hand is one of the most complex anatomical structures of the human body with visible anatomical variations among individuals in terms of digit length and bone shapes (Durand et al, 2011). In addition its numerous DoFs, small dimensions and the large mobility of each finger make it one of the most challenging body parts in terms of robotics and/or orthotics (Jones, 1997), (Grebenstein et al, 2012).…”