Origin and Distribution of the Brachial Plexus in Two Procyonids (Procyon cancrivorus and Nasua nasua, Carnivora).

Procyon cancrivorus and Nasua nasua are two procyonids with different evolutionary adaptations to use their thoracic limbs. Therefore, this study aimed to characterize the differences in the brachial plexus between both species. Five P. cancrivorus and five N. nasua cadavers were used to perform this investigation with the permission of the bioethics committee and environmental license. Gross dissections were performed on the cervical, pectoral, and thoracic limb regions to find the origin and distribution of the brachial plexus. The brachial plexus of both species originated in a variant manner from C5-T1, C5-T2, C6-T1, or C6-T2. All brachial plexus nerves were observed and, interestingly, the musculocutaneous sent a communicating branch to the median nerve medially to the axillary artery, forming an ansa axillaris in both species. An ansa pectoralis was also observed medially to the axillary artery. Additionally, in P. cancrivorus, the musculocutaneous nerve innervates the pronator teres and flexor carpi radialis muscles and communicates with the median nerve at the elbow level to continue as a common trunk at the antebrachium. The brachial plexus has differences between both procyonids, although in both species, it could conserve a primitive arrangement present within the infraorder Arctoidea.

Anatomy of the thoracic limb muscles of wild boars (Sus scrofa, Artiodactyla: Suidae).

The study of the muscular anatomy of wild boar (Sus scrofa) is important, because it allows the understanding of the locomotor and evolutionary aspects, besides the improvement of surgical techniques used by veterinarians in swine. Thus, the objective of this study was to describe the morphology and disposition of the shoulder and arm muscles of S. scrofa. Twelve young specimens of hybrid S. scrofa, six males and six females were fixed and dissected following usual anatomy techniques. The bones of two specimens were prepared to analyze the fixation points of the muscles. The shoulder muscles presented fixation at the scapula and humerus, in distinct bone accidents, and were divided on lateral and medial faces. On the lateral face, the deltoid (divided in acromial and scapular parts), supraspinatus, infraspinatus (divided in cranial and caudal parts) and teres minor (deep to the caudal part of the infraspinatus) muscles were found. In the medial face, the subscapular, coracobrachialis and teres major muscles were observed. The arm muscles were arranged essentially around the humerus and were seen largely on its medial face, namely biceps brachii (originated by a single tendon), brachialis, tensor fasciae antebrachii (fused with the long head of the triceps brachii), triceps brachii (divided in lateral, long and medial heads) and anconeus (located mostly on the lateral side) muscles. Thus, it can be concluded that the S. scrofa presented seven muscles in the shoulder region and six muscles in the arm region, all with morphological similarities to domestic and some wild animals. Some differences were found, for the most part, in the shape, division and fixation points of certain muscles.