Ontogenesis and Homologies of Human Carpal and Tarsal Components

Abstract

The question of the origin, derivation and homologies of carpal and tarsal components has been an onerous problem in developmental anatomy for more than a hundred years. Interest was evoked by the work of Gegenbaur (1865) where the structure of the tetrapod extremity was derived for the first time from the fin of elasmobranch fishes. In the course of the subsequent development of the problem this idea was gradually exactified and geometrised (Gegenbaur, 1870a, b, c, d). Less known in the history of the problem, but quite important for later views on the development of the extremities is Gegenbaur’s consideration of the uniserial “archipterygium ” as the elemental extremity type, presented in these early works. From the archipterygium he derived the five-toed extremity so that he at first located the main axis through the radius and the fifth finger and derived the remaining fingers as collateral rays (Fig. 1 A). Later on, influenced by Huxley’s criticism (1873), Gegenbaur (1876) transposed the main extremity axis into the ulnar margin of the uniserial archipterygium and other fingers again were derived in the form of collateral rays.