Origin and distribution of the brachial plexus in kinkajou (Potos flavus – Schreber, 1774)

Abstract

The kinkajou (Potos flavus) is a carnivoran adapted for arboreal quadrupedal locomotion along with a prehensile tail. The thoracic limb bones and muscles of this species have been studied, but the knowledge about its nerves is still scarce. This knowledge is necessary to perform several veterinary procedures, and to review the differences among carnivoran species. Thus, the objective of this study was to describe the origin and distribution of the brachial plexus in Potos flavus. Thereby, both brachial plexuses of five specimens were dissected (10). Seven plexuses originated from C6-T2 (70%), whilst three plexuses originated from C5-T2 (30%). Additionally, C6 and C7 formed two cranial trunks, and C8, T1 and T2 formed two caudal trunks. All nerves from the brachial plexus that have been reported in carnivorans were successfully located. In addition, we found one nerve reaching the teres major muscle originating directly from the brachial plexus and not from the axillary nerve as reported in other carnivorans. The brachiocephalic nerve was found partially innervating the cleidobrachialis muscle (50%), but this muscle always was innervated by the axillary nerve. Moreover, one to three subscapular nerves were found, and the musculocutaneous nerve formed two communicating branches (proximal and distal) to the median nerve. However, the distal communicating branch of the musculocutaneous nerve was absent in two specimens (40%). In conclusion, the brachial plexus of P.flavus was differentiated mainly with other carnivorans by a higher contribution from T2, formations of trunks, and one independent nerve to the teres major muscle.