Inferior Rectal Nerve, Posterior View

Description

Posteriorly oriented male perineal anatomy centers on the inferior rectal nerve as it branches from the pudendal nerve within the pudendal canal (Alcock canal) along the lateral wall of the ischioanal fossa. From a position medial to the obturator internus fascia and lateral to the external anal sphincter, the nerve courses inferomedially across the fat of the ischioanal fossa toward the anal canal and perianal skin. Nearby, you would expect to appreciate the internal pudendal vessels accompanying the pudendal nerve, the sacrotuberous ligament posteriorly, and the levator ani forming the superior boundary of the fossa. Small ganglionic elements and plexiform interconnections around the pudendal trunk may be suggested where the branch takes origin. For surgical anatomy, this branch matters because it carries the dominant somatic sensory supply to the inferior anal canal and perianal region and contributes motor fibers to the external anal sphincter, so injury can produce perianal hypoesthesia and impaired voluntary continence. Pudendal canal dissection during drainage of ischioanal abscess, fistula surgery, or transgluteal approaches risks traction or transection of the inferior rectal nerve where it crosses the fossa. This is the landmark clinicians chase when differentiating pudendal neuralgia from primary anorectal pain syndromes. A short course, high consequence. Use this illustration in colorectal surgery atlases, pelvic floor and perineal anatomy teaching sessions, and anesthesia materials illustrating pudendal nerve block technique and the sensory territory that should be covered. It also fits neurology and pain medicine references discussing entrapment near the sacrospinous ligament and pudendal canal with referral to the perianal region. Anatomical accuracy verified by SciePro's Medical Advisory Board.