The innervation of the levator ani and coccygeal muscles and the external anal sphincter was studied by anatomic dissection in 6 clinically normal male dogs and by electrical stimulation in 5 clinically normal male dogs. Variations in innervation occasionally were found that were comparable to those reported in previous studies. Electromyographic recordings were made from the levator ani and coccygeal muscles and from the anal sphincter in 40 dogs during perineal hernia repair. Spontaneous potentials of 4 types were found in 35 dogs: fibrilation potentials, positive sharp waves, complex repetitive discharges, and fasciculations. Biopsy specimens of the cranial part of the levator ani muscle were taken in 12 dogs during perineal hernia repair. Histologic examination revealed atrophy in 7 specimens. Spontaneous potentials were recorded from all muscles with histologic evidence of atrophy. All examinations of the levator ani muscle concerned the cranial, part of this muscle, because the caudal part was absent in all 40 dogs. From combined results of electromyography and histologic examination, it was concluded that atrophy of the muscles of the pelvic diaphragm, which develops in some dogs with perineal hernia, is likely to be of neurogenic origin. Nerve damage is localized in the sacral plexus proximal to the muscular branches of the pudendal nerve or in the muscular branches separately.

<p>The morphology and innervation of the diaphragm in 3 species of deers (Manzana americana, Manzana simplicicornis and Blastoceros bezoarticus) were dissected after having been fixed in 10% formaldehyde solution. The diaphragm in 3 species appeared thin, having a reduced peripheral muscular portion, a large centrum tendineum and thick pillars. The phrenic nerves presented a terminal trifurcation (45% on the right and 18.2% on the left) or a bifurcation into (a) a dorsal branch and a lateroventral trunk (54.5% on the left and 36.4% on the right) or (b) a ventral branch and a laterodorsal trunk (27.3% on the left and 18.2% on the right). Dorsal, lateral and ventral branches of the phrenic nerves supply the lumbar, costal and sternal portions of the diaphragm, respectively. Connections were found between small branches of the phrenic nerves.</p> | <p>A morfologia e a inervação do diafragma foram estudadas em três espécies de veados (Manzana americana, Manzana simplicicornis e Blastoceros bezoarticus). Os diafragmas foram fixados em solução aquosa de formol a 10% e o método utilizado para evidenciar a ramificação e a distribuição dos nervos frênicos foi o da dissecação. Os resultados mostraram que os diafragmas das três espécies são pouco espessos, possuem porção carnosa periférica reduzida, um centro tendíneo (folíolos) amplo e delgado e pilares robustos. Quando consideradas em conjunto as três espécies, os nervos frênicos dividem-se por trifurcação (mais à direita) e por bifurcação (ramo dorsal e tronco lateroventral - mais à esquerda - e ramo ventral e tronco laterodorsal - percentagens sem diferença estatisticamente significante entre os dois lados). Os ramos dorsais, laterais e ventrais destinam-se às partes lombar, costal e costal estemal respectivamente. Foram encontradas conexões entre os filetes nervosos.</p>