Ramification and distribution of the phrenic nerves in diaphragm of horses

Abstract

The phrenic nerve distribution in 50 diaphragmas from mixed breeding adult horses (25 males and 25 females) obtained from a slaughter house ("Avante"), located in Araguari, State of Minas Gerais, was studied. The results indicated the following characteristics: 1) the ventral branch and laterodorsal trunk were extended 42 times (84%) to the right side, 5 times (10%) to the left, while the dorsal and the lateroventral trunk were 40 times (80%) to the left and 2 times (4%) to the right. The common origin of the dorsal, lateral and ventral branch were 6 times (12%) to the right and 5 times (10%) to the left. 2) The right and left bifurcation of the phrenic nerve were symmetrically arranged in: laterodorsal trunk and ventral branch 9 times (18%); lateroventral trunk and dorsal branch 5 times (10%) and simultaneously in lateral and ventral dorsal branches 2 times (4%). 3) The right and left dorsal branches of the phrenic nerve were always distributed on the limbar portion (medial and lateral pillar) in relation to their origins. The distribution of the nervous fillets from the right dorsal branch to the dorsal foliolo was: one fillet 10 times (20%) and 2 fillets 1 time (2%) respectively. To the tendinous center one fillet (2%) was observed. From the left dorsal branch in 50 times (100%) there was one fillet going to the right medial pillar. In relation to the left dorsal foliolo there was: one fillet 3 times (6%) and 2 fillets 3 times (6%) and in relation to the tendinous center there was: one fillet 3 times (6%); 2 fillets 2 times (4%) and 4 fillets just once (2%). 4) From the right and left lateral branches of the phrenic nerve in all observations (100%) there were fillets going to the lateral dorsal region in both sides. The distribution of the emerging fibers from the right lateral branch to the do sal foliolo was 1  fillet 6 times (12%); 2 fillets 3 times (6%); 3 fillets 1 time (2%) and to the right lateral pillar 1 fillet 2 times (4%). The distribution of the emerging fibers from the left lateral branch to the dorsal foliolo was 1 fillet 8 times (16%) and 2 fillets 2 times (4%). 5) The right and left ventral branches of the phrenic nerve were distributed to the lateroventral and external region in all observations (100%). It was also observed that from the right ventral branch to the tendinous center, there was one fillet in three observations (6%); to the caudal portion of the vena cava there was one fillet in two observations (4%) and to the right ventral foliolo there  as one fillet in just one observation (2X ) . The homolateral anastomosis, between the dorsal and lateral branches, was seen in 10 observations  (20%). The distribution of these anastomosis between the dorsal and lateral branch was: to the right side in 6 observations (12%); to the left side in 2 observations (4%) and in the both sides in 2 observations (4%). The heterolateral anastomosis between the right and left dorsal branch was registered just in one observation (2%). 7) There was no significant difference (p < 0,05) in the distribution of diaphragma nerves between males and females.