The development of the human wrist joint during the fetal period

摘要

AbstractRecent morphological studies have revealed that the hominoid ulna has become progressively excluded from direct articulation with the carpus by the elaboration of an intervening intra‐articular meniscus, which in gibbons contains a bony lunula. In man this meniscus has merged with the triangular articular disk, forming a confluent proximal articular surface and constricting off a diverticulum of the synovial radiocarpal cavity, the prestyloid recess, which may lodge the ulnar styloid process. The present study reassesses the development of the human fetal joint in the light of these findings. Initially separate radioscaphoid, radiolunate and ulnotriquetral synovial cavities communicate to form a single continuous wrist joint cavity; the pisotriquetral cavity, at first independent, frequently establishes continuity with the wrist joint cavity, the normal condition in most Primates. After the 60 mm C. R. stage the ulna withdraws from the carpus and an intervening meniscus and prestyloid recess are elaborated. In a number of specimens a cartilaginous nodule, the so‐called intermedium antebrachii, has been observed adjacent to the ulnar styloid process. There is little doubt that this nodule, which may ossify, is homologous with the gibbon lun