Corpus: Pudendal nerve

The pudendal nerve arises from the sacral plexus, sometimes referred to as the pudendal plexus. It comprises fibers originating from the spinal cord segments S1 to S4, though some sources suggest it only includes fibers from S2 to S4. This nerve transmits both general somatosensory and somatomotor fibers.

Originating in the ventral part of the anterior horn (laminae IX) at the Onuf nucleus, the motor fibers of the pudendal nerve, along with sensory fibers leading to the posterior horn, traverse the infrapiriform foramen. The nerve then loops around the spina ischiadica before it enters the ischiadicum minus foramen. Within the ischioanal fossa, the pudendal nerve travels through the pudendal canal (Alcock canal), a fascial duplication of the internal obturator muscle. It subsequently branches into its terminal divisions: the perineal nerves, the inferior rectal nerves, and either the dorsal nerve of the penis or the dorsal clitoral nerve.

3.1. Inferior rectal nerves

The inferior rectal nerves provide motor innervation to the external anal sphincter and sensory input to the skin surrounding the anus. Damage to these nerves may result in fecal incontinence.

3.2. Perineal nerves

The perineal nerves serve the perineum's muscles, including the superficial and deep transversus perinei muscles and the bulbospongiosus and ischiocavernosus muscles.^[1] They also innervate the external urethral sphincter. Lesions of these nerves can lead to urinary incontinence. In males, the perineal nerves also innervate the dorsal side of the scrotum via the posterior scrotal nerves, while in females, they innervate the labia majora through the posterior labial nerves.

3.3. Dorsal nerve of the penis

The dorsal nerve of the penis provides sensory input to the dorsal side of the penis, including the glans, prepuce, and corpus cavernosum, and also motor functions to the deep transverse perineal muscle.

3.4. Dorsal clitoral nerve

The dorsal clitoral nerve delivers sensation to the dorsal region of the clitoris.

The pudendal block, which anesthetizes the pudendal nerve, is frequently performed during vaginal birth to manage pain.