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Chapter 12. INNERVATION OF GENITAL O RGANS, ASSOCIATED STRUCTURES AND CAUDAL ALIMENTARY CANAL

12.1 PUDENDAL NERVE

The pudendal nerve (or its branches) is the only large nerve in the perineal region. It arises from the ventral rami of sacral nerves S1-3 in the dog and cat, (Three sacral vertebrae in the small animal species and five in large animals.) and is the larges source of innervation.

12.2 BRANCHES OF THE PUDENDAL NERVE

PROXIMAL CUTANEOUS BRANCH: This is a sensory branch to the skin over the semitendinosus muscle.

 

12.3 DISTAL CUTANEOUS BRANCH

The distal cutaneous branch is also purely a sensory nerve but larger than the proximal branch because of its more extensive course to the skin of the caudal part of the scrotum.

12.4 DEEP PERINEAL NERVE

Motor and sensory nerve. It is motor to the following muscles in the perineal region: External anal sphincter muscle (lateral part).; Levator ani muscle (a portion of it).; Urethralis muscle.; Ischiocavernosus muscle.; Bulbospongiosus muscle. It is sensory to mucosa of the terminal rectum and anal canal. After passing around the ischial arch, the pudendal nerve descends through the subpelvic tendon and divides into the dorsal nerve of the penis (Dorsal nerve of clitoridis in female.) and the superficial perineal nerve (Mammary branch of the pudendal in the female.).

12.5 DORSAL NERVE OF THE PENIS

This is the principal sensory nerve to the penis in all male animals, and the motor nerve to the smooth muscle retractor penis through the sympathetic fibers which it carries.

The right and left dorsal nerves of the penis become intimately associated with the dorsolateral surface of the penis and the dorsal vessels of the penis. Many small branches leave the dorsal nerves as they follow the dorsal surface of the penis, sending numerous perforating branches through the tunica albuginea along the way and terminating in the glans penis.

12.6 SUPERFICIAL PERINEAL NERVE

The other terminal branch of the pudendal nerve is the superficial perineal nerve which soon divides into at scrotal branch to the skin of the scrotum and septum of scrotum and a preputial branch which supplies the retractor preputial branch which supplies the retractor preputiae and skin of the preputial orifice.

12.7 GENITOFEMORAL NERVE ("External spermatic"nerve.)

Its origin is from the ventral rami of 12, 3, 4 spinal nerves. It passes through the inguinal canal on the lateral surface of the cremaster muscle. It has a femoral branch to the cremaster muscle but chiefly to the mid portion of the external genitalia, the retractor preputiae muscle and the lateral wall of the scrotum.'CRANIAL PREPUTIAL' NERVES

Ventral cutaneous branches of T9-13, L1-L2 are collectively called the "cranial preputial" nerves. They are sensory to the skin of the cranial part of the prepuce and motor to the cranial and caudal preputial muscles.

12.8 LATERAL THORACIC NERVE

A preputial branch of the brachial plexus, the lateral thoracic nerve from C8, T1-T2, also supplies motor fibers to the retractor and protractor preputial muscles.