Ischiorectal fossa

The ischiorectal fossa (Ischioanal fossa in some texts) is a fat-filled, wedge-shaped space located on either side of the anal canal, between the pelvic diaphragm and the lateral wall of the pelvis.

Boundaries:

• Medially: external anal sphincter and pelvic diaphragm (levator ani muscle).

• Laterally: ischium and the obturator internus muscle covered by its fascia.

• Posteriorly: sacrotuberous ligament and gluteal muscles.

• Anteriorly: continuous with the perineal region.

Contents:

• Loose connective tissue and fat (fat body of ischiorectal fossa)

• Pudendal nerve and internal pudendal vessels (within the pudendal canal or Alcock's canal).

• Caudal rectal nerve and vessels.

Function:

• Acts as a cushion and allows expansion of the anal canal during defecation.

• Provides a pathway for neurovascular structures to reach the perineum and external genitalia.