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.
