The ischioanal fossa (formerly called ischiorectal fossa) is the fat-filled wedge-shaped space located lateral to the anal canal and inferior to the pelvic diaphragm. It is somewhat prismatic in shape, with its base directed to the surface of the perineum and its apex at the line of meeting of the obturator and anal fasciae.

It has the following boundaries:^[1]

The contents include:

• Inside Alcock's canal, on the lateral wall
  • internal pudendal artery
  • internal pudendal vein
  • pudendal nerve
• Outside Alcock's canal, crossing the space transversely
  • inferior rectal artery
  • inferior rectal veins
  • inferior anal nerves
  • fatty tissue across which numerous fibrous bands extend from side to side allows distension of the anal canal during defecation

• Anal triangle