Pudendal Canal

Of Alcock

• Connective tissue tunnel in the lower lateral wall of the fossa

• Overlies Obturator Internus and medial side of the Ischial Tuberosity

• Canal formed by a splitting of the Obturator Fascia above the Falciform Process of the Sacrotuberous Ligament

• Contains:

  • Pudendal Nerve
  • Internal Pudendal Vessels

• The canal conducts from the Lesser Sciatic Notch to the Deep Perineal Pouch above the Perineal Membrane

• Pudendal Nerve and Internal Pudendal Vessels leave the pelvis through the Greater Sciatic Foramen

  • Passes beneath the lower border of Piriformis to reach the buttock
  • Then turn and enters the Lesser Sciatic Foramen
  • Vessels pass over the tip of the Ischial Spine and the nerve pass more medially over the Sacrospinous Ligament

• Inferior Rectal Branches of the Pudendal Nerve:

  • Run transversely across the Ischioanal Fossa from the Pudendal Canal towards the Anal Canal
  • Course arches convexly upwards through fat towards apex and then down towards the canal
  • Incisions to drain Ischiorectal abscesses do not usually interfere with them
  • Supplies the External Anal Sphincter, mucous membrane of the lower Anal Canal and peri-anal skin NB: Lateral wall of the Left Ischioanal Fossa from behind

• At the front of the Ischioanal Fossa, the Posterior Scrotal (Labial) Nerves and Vessels (From the Pudendals) pass superficially into the urogenital region

• At the back of the Ischioanal Fossa, the Perineal Branch of S4 Nerve and Perforating Cutaneous Nerve traverse the fossa