Complete extensor digitorum profundus complex: a deep hand extensor muscle to the medial four digits

A reverse form of Linburg–Comstock variation with comments on its etiology and demonstration of interactive 3D portable document format

“…With regards to its possible etiology, it was speculated that variants in the adult stage were found to be commonly expressed during the embryonic period [ 4 ], for example, the dorsometacarpales [ 4 , 26 ], a group of primitive digital extensors. Recently, we discovered a variant extensor muscle which extended to all five digits in the deep extensor compartment of forearm [ 20 ], similar to the extensor digitorum profundus complex found in non-human primate species [ 18 ]. These findings suggest the possibility that the musculotendinous LCV could be an accessory anatomical variant or a vestigial structure.…”

Extensor Indicis Radialis and Extensor Medii Proprius Associated with an Unknown Fibromuscular Slip: a Case Report

“…The EIR is an extremely rare variation which existed in only 0.2% of limbs [8]. These variants are believed to be part of the extensor profundus complex, a common digital extensor in the in the deep layer of the posterior forearm muscle group, which variably exists in non-human primate species [9]. Despite the considerable amount of literature studying the aforementioned variations, much less attention is given to the dorsometacarpales, short digital extensors which were lost in our adult ancestors approximately 250 million years ago, within the transitions that led to mammals.…”