Brachial plexus formation in Jaguarundi (Puma yagouaroundi).

Puma yagouaroundi is a wild felid with wide distribution on the American continent. This paper aims to describe the origin and motor distribution of the nerves of the brachial plexus of P. yagouaroundi and compare the findings with the available descriptions for the Carnivora order. Fourteen brachial plexuses of specimens collected dead on highways were dissected (five males and two females). In most cases (57%), the brachial plexus originated from the ventral spinal branches of C5, C6, C7, C8 and T1. The C7 branch was the one that most contributed to the formation of the plexus nerves (57.7%). Among all dissected nerves, 23.6% were unisegmental and 76.4% plurisegmental. The radial nerve was the thickest and innervated the largest number of muscles, while the caudal pectoral nerve showed the most varied formation. Intraspecific polymorphisms occurred in the plexus, although the distribution of the nerves to the muscles had an evident constancy among the individuals. Due to the similarities, locoregional blocking techniques may consider the same anatomical landmarks stipulated for domestic cats. Comparison with the descriptions of other carnivorans allows speculating a polymorphism at the plexus origin, in contrast to the conservative innervation of the muscles in the order Carnivora.