Origin, distribution, and insertion of the brachial plexus nerves in Blue-and-yellow Macaws (Ara ararauna, Linnaeus, 1758)

Abstract

Brazil has about 80 species of parrots cataloged, and five of them are identified as Macaws. As the vast majority of birds, Macaws use flight as their primary means of locomotion. However, the strength and power generated during the cycle of beating wings require a mechanism of active neuromuscular control and specialized adaptations of muscles responsible for flight, which are innervated by the brachial plexus. This study aims to describe the origin and distribution of peripheral nerves that make up the brachial plexus in Blue-and-yellow Macaw (Ara ararauna, Linnaeus, 1758), in order to aid the veterinarian to recognize and locate neuromuscular lesions in this species. We used five dead bodies, obtained from the Screening Center for Wild Animals in Paraíba, Brazil, in which the nerves were identified by direct dissection. Four nerve roots were viewed, originating three nerve trunks, which stem from the intervertebral spaces between the tenth cervical vertebra and the second thoracic vertebra. Nerves from the dorsal cord innervated extensor muscles, while ventral cord nerves innervated flexor muscles of the wing, in addition to the pectoral branches, responsible to innervate the superficial thoracic and shoulder muscles.

Keywords

• Anatomy
• Birds
• Innervation
• Parrots
• Peripheral nervous system