Abstract
The aim of this study was to describe the origin and branches of the brachial plexus nerves in S. villosus, as well as the innervated musculature, contributing information to the field of comparative animal anatomy and providing insights for applied studies. Fifteen adult cadavers (eight males and seven females), previously identified, sexed, and fixed with a 10% aqueous formaldehyde solution, were used. They underwent digital radiographic examinations of the cervical region to characterize the number of cervical vertebrae. The nerves were dissected up to the innervation of the intrinsic and extrinsic musculature of the thoracic limb. With the assistance of a costotome, the vertebrae were removed until the visualization of the spinal cord and the roots giving rise to the nerve branches. The specimens presented seven cervical vertebrae, and the brachial plexus was characterized as post-fixed, formed by connections between the last four cervical spinal nerves (C5, C6, C7, and C8) and the first two thoracic nerves (T1 and T2). The cranial, middle, and caudal trunks originated the suprascapularis, subscapularis, axillary, musculocutaneous, radial, median, and ulnar nerves for intrinsic musculature, and the cranial pectoral, caudal pectoral, lateral thoracic, long thoracic, and thoracodorsal nerves for extrinsic musculature. The ventral branches that contributed the most to the plexus formation in the right antimer were C5 and C8, while in the left antimer, it was C7. The resulting nerves and the innervation for extrinsic and intrinsic musculature were similar to those observed in other rodents and representatives of the Mammalia class in general.