Origem do nervo frênico e inervação do diafragma em catetos (Tayassu tajacu, Linnaeus 1758) e cachorro-do mato (Cerdocyon thous, Linnaeus 1766)

Abstract

The collared peccary and the crab-eating fox are species widely distributed in American territory; however, deforestation, hunting and habitat fragmentation are threats facing these animal populations. Research on the morphophysiology of wild animals has received considerable contributions from renowned institutions across the country, which promote dissemination and clarification of professionals from different areas of knowledge. Thus, this detailed study may represent important factor for the preservation and protection of fauna. Therefore, the study aims to describe the macroscopic anatomy of the phrenic nerve and detail its origin and distribution in the diaphragm muscle of collared peccary and crab-eating fox. The phrenic nerve of 16 Tayassu tajacu specimens originates from C4, C5 and C6, and can receive contribution of C7 and the pectoral nerve to its formation. Upon reaching diaphragm muscle, it branches into costoesternal trunk and lumbar branch in greater frequency on both to the right and to the left (81.25% and 68.75%, respectively); and in the lumbocostal trunk and sternal branch in less frequency (18,75% on the right and 31.25% on the left). In the crab-eating fox when compared to the domestic dog, there is a similar origin from C5, C6 and C7 to Cerdocyon thous and C5, C6 and occasionally C7. Upon reaching the diaphragm, this anatomical component ends in lumbocostal trunk and sternal branch in the crab-eating fox; in costoesternal trunk and lumbar branch in greater frequency and in lumbocostal trunk and sternal branch in the domestic dog. These structures emit branches both on the right and on the left to corresponding pars lumbalis, pars costalis and pars sternalis. So, the description of the phrenic nerve anatomy is important for surgical approaches and anesthetic protocols in cervico-thoracic surgeries, in which prior anatomophysiological knowledge is necessary.