Thirty diaphragms of sheep of Santa Inês breed were studied regarding their origin, division and arrangement of the right and left phrenic nerves (Fde), and the participation of other nerves in the innervation of the diaphragm. By fixing and dissecting pieces, it was found that phrenic nerves (F) frequently come from the ventral branches of the 5th (C5) and 6th (C6) cervical spinal nerves (Ec), at right (46.67%) and at left (43.33%). The F often form a lumbocostal trunk, sternal branches at right (40.00%) and lumbar, costal and esternal branches at left (36.68%). The lumbar branches of F innervate frequently at left (96.67%) the homolateral pillar of the diaphragma, and at right (50.00%) they give fillets to Vena cava caudalis. The costal branches of the F innervate at left (90.00%) and at right (76.66%) the dorsal and ventral regions of the pars costalis. The sternal branches of the F innervate at right (100.00%) and at left (83.33%) the pars sternalis and the ventral region of the pars costalis at the same side. The intercostal nerves (VII to XII pairs, 63.33%) contribute to innervate the diaphragm of Santa Inês sheep.
Anatomy; phrenic nerves; sheep; diaphragma; nervous system
