Anatomical description of brachial plexus nerves in orange-spine hairy dwarf porcupine (Sphiggurus villosus Cuvier, 1823) (Rodentia: Erethizontidae)

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. The patients underwent digital radiographic examinations of the cervical region to characterize the number of cervical vertebrae. The nerves were dissected to visualize the innervation of the intrinsic and extrinsic musculature of the thoracic limb. With the assistance of a costotome, the vertebrae were removed until visualization of the spinal cord and the roots, which gave rise to the nerve branches. The specimens presented seven cervical vertebrae, and the brachial plexus was characterized as postfixed, 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 originate from the suprascapularis, subscapular, axillary, musculocutaneous, radial, median, and ulnar nerves for the intrinsic musculature and from the cranial pectoral, caudal pectoral, lateral thoracic, long thoracic, and thoracodorsal nerves for the extrinsic musculature. The ventral branches that contributed the most to plexus formation in the right antimer were C5 and C8, while in the left antimer, they were 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.