Which fascia forms the lateral boundary of the ischioanal fossa?

Which fascia forms the lateral boundary of the ischioanal fossa?

• A. Fascia of obturator internus
• B. Pelvic fascia
• C. Endopelvic fascia
• D. Pudendal canal fascia

Answer: (A)

The lateral boundary of the ischioanal fossa is formed by the fascia covering the obturator internus muscle. This obturator internus fascia creates the thick lateral wall of the fat-filled space that sits on either side of the anal canal. Within this fascia runs Alcock’s canal, the pudendal canal, which houses the internal pudendal vessels and pudendal nerve. Thus, the fascia of obturator internus precisely defines the lateral limit. Pelvic or endopelvic fascia are associated with other pelvic relationships and don’t form this lateral boundary, and the pudendal canal fascia is not a separate boundary—it’s the canal contained within the same obturator internus fascia.

The lateral boundary of the ischioanal fossa is formed by the fascia covering the obturator internus muscle. This obturator internus fascia creates the thick lateral wall of the fat-filled space that sits on either side of the anal canal. Within this fascia runs Alcock’s canal, the pudendal canal, which houses the internal pudendal vessels and pudendal nerve. Thus, the fascia of obturator internus precisely defines the lateral limit. Pelvic or endopelvic fascia are associated with other pelvic relationships and don’t form this lateral boundary, and the pudendal canal fascia is not a separate boundary—it’s the canal contained within the same obturator internus fascia.