Comportamento dos nervos frênicos no músculo diafragma de Tamanduá-bandeira (Mymecophaga tridactyla, Linnaeus, 1758)

Abstract

The ramification and distribution of the right (RPN) and left (LPN) phrenic nerves in Myrmecophaga tridactyla were investigated in 17 specimens of diaphragm muscles, nine males and eight females, preserved in 10% formaldehyde solution. It was found that the phrenic nerves branched predominantly to the fleshy parts of the diaphragm muscle (lumbar, costal and sternal) and the incidence of terminal branches most frequently was the bifurcation into the dorsolateral trunk and ventral branch for the RPN (n=17; 100). %) and for the LPN (n=16; 94.12%). As for the symmetry of the branching of the phrenic nerves in the giant anteater, it was found that in 94.12% it presented the pattern of bifurcation into the dorsolateral trunk and ventral branch. Connections from the emission of the dorsal branch of the LPN towards the dorsal branch of the RPN were observed in four diaphragms of the giant anteater (23.53%). In one case, referring to the RPN, there was the emission of a nerve to the tendon center. In all diaphragms in the present study, the dorsal branches of the phrenic nerves, both the right and the left, innervated the lumbar parts. Likewise, the right and left lateral branches of the phrenic nerves innervated the costal parts. The ventral branches, right and left, innervated, in all cases, the costal and sternal parts. In 11 specimens (64.70%), there was a contribution of nerve threads that originated from the left dorsal branch and were distributed in the right antimere, more precisely in the right lumbar part.