Pudendal canal

The pudendal canal is a fascial conduit located along the lateral wall of the ischiorectal (ischioanal) fossa, providing a protected passage for the pudendal nerve and the internal pudendal vessels. It is critical in the innervation and blood supply of the perineum, external genitalia, and anal region.

Anatomical Structure

Location

• It lies within the obturator fascia, which covers the internal obturator muscle.

• The canal is found medial to the ischial tuberosity, within the ischiorectal fossa, a fat-filled depression between pelvic diaphragm and skin.

Formation

• The pudendal canal is not a distinct tubular structure like a true duct or vessel, but rather a fascia-enclosed groove or tunnel formed by the splitting of the obturator fascia.

• It starts near the lesser sciatic notch and runs caudally.

Contents

The pudendal canal transmits:

• Pudendal nerve – main somatic nerve of the perineum.

• Internal pudendal artery – a branch of the internal iliac artery.

• Internal pudendal vein – accompanying vein of the artery.

In some species, perineal branches or a caudal rectal nerve (a branch of the pudendal nerve) may exit the canal early to supply the external anal sphincter.

Species-Specific Considerations

Dog

• The pudendal nerve arises from sacral spinal nerves (S1-S3) and courses through the canal with internal pudendal vessels.

• The pudendal canal is well-developed and easily identifiable.

Horse

• The anatomy is similar to the dog, but the pudendal canal may be less distinct. However, its contents are functionally critical for breeding and defecation.

• The caudal rectal nerve often branches early to innervate the anal sphincter before entering the canal.

Ruminants

• In cattle and small ruminants, the pudendal canal structure is similar, though the perineal region may show species-specific vascular branching patterns.

Clinical Relevance

Nerve Blocks

• The pudendal nerve block is performed near the ischial spine or through the ischiorectal fossa to desensitize the perineum during obstetric or surgical procedures.

Injuries and Pathologies

• Damage or compression within the pudendal canal (e.g., from trauma or chronic pressure in large animals) can result in:

  • Fecal or urinary incontinence

  • Impaired penile or clitoral function

  • Perineal anesthesia

Surgical Landmark

• The canal’s location makes it a key landmark during perineal surgeries or castrations.