The ischioanal (or ischiorectal) fossa is a fat-filled space of the perineum.
The ischioanal fossa is a paired triangular-shaped space lateral to the anal canal with an apex directed anteromedially towards the pubic symphysis. Each ischioanal fossa is separated from the other by the anococcygeal body, but they do still communicate superiorly to this and posterior to the anal canal.
Many textbooks and surgeons use the term ischiorectal fossa, however even a cursory review of the anatomy shows that the region is closely related to the anal canal, and not, the rectum.
- roof: levator ani muscle
- floor: deep transverse perineal fascia
- medial wall: external anal sphincters/anal canal; levator ani muscle
- lateral wall: ischial tuberosity; obturator internus muscle; obturator fascia
- apex: intersection of the levator ani and obturator internus muscle
- ischioanal (or ischiorectal) fat pad
- pudendal canal: lies in a fibrous sheath on the lateral wall and itself contains the pudendal nerve and internal pudendal vessels
- inferior rectal branches of the pudendal nerve
- posterior scrotal (labial) nerves and vessels
- perineal branch of S4
- perforating cutaneous nerve
- lymphatic trunks