Craniolateral forearm muscles of the crab-eating raccoon (Procyon cancrivorus) and a comparative review with other carnivorans

Abstract

ABSTRACT The crab-eating raccoon Procyon cancrivorus (Cuvier, 1798) is a species of the order Carnivora and family Procyonidae with a geographical distribution in Central and South America. Although crab-eating raccoons use scansorial locomotion, they also have aquatic habits, displaying greatly developed skills when handling their food. This species can frequently be found in wildlife care centers due to injuries caused by domestic dogs, humans, and car collisions. Having knowledge of the species’ gross anatomy and anatomical bases is imperative to perform the most appropriate medical and surgical procedures. Thus, the objective of this investigation was to analyze the interspecific and intraspecific differences of the craniolateral forearm muscles of Procyon cancrivorus. Gross dissections were performed in four specimens describing the origin, insertion, shape, innervation, and arterial supply of the craniolateral forearm muscles. There is a constant and well development of brachioradialis muscle comparatively to that described in strictly cursorial species; the extensor carpi radialis muscle has two bellies that are fused proximally; the extensor digitorum communis muscle can also extend the tendon to the digit I as an anatomical variant, and the extensor digiti I and II muscle also extends the tendon to digit III. All are innervated by the deep branch of the radial nerve, and their arterial supply is mainly by the radial collateral, cubital transverse, and cranial interosseous arteries. The anatomical characteristics observed in this study complement the previous descriptions for Procyon cancrivorus, and the anatomical variants found in this species can also be in other carnivorans. Thus, the intraspecific anatomical variations of the digital extensor muscles in P. cancrivorus are phylogenetic traits that can occur as a common pattern or as anatomical variants in other species of the order Carnivora.