Contribution to the study of diaphragm innervation in Nelore bovines

The phrenic nerves, in Nelore bovines, divide more frequently (60%) in a dorsal branch and a ventrolateral trunk, in both left and right sides. Another division, in trifurcation, giving off dorsal, lateral and ventral branches occurred in 23.3% of cases in the right side and in 30% left side. The division in ventral branch and dorsolateral trunk was observed in 16.6% of cases in the right side and 10% left side. The dorsal branches, both left and right, were distributed among their corresponding lumbar portions in all the cases verified. In 3% of the muscles studied, the right dorsal branch sent a nervous twig to caudal vena cava, and in 73.3% of the muscles, the left dorsal branch innervated the left lumbar portion and also sent some twigs which, after crossing the middle line, distributed in the right lumbar portion, ventral to esophageal hiatus. The lateral and ventral branches, in both left and right sides, innervated corresponding parts of the muscle. Connections (anastomosis) were observed between left lateral and dorsal branches in 10% of cases, and between dorsal left and right branches in 6.7% of cases.