On an axial CT of the pelvis at the level of the ischioanal fossa, a structure is identified in a fascial tunnel on the lateral wall of the fossa. This is the pudendal (Alcock's) canal containing the pudendal nerve and vessels. Which muscle forms the lateral wall of the ischioanal fossa through which this canal runs?
- A Gluteus maximus
- B Levator ani
- C Obturator internus ✓
- D Piriformis
Correct answer: C. Obturator internus
Explanation
The ischioanal fossa is bounded laterally by the obturator internus muscle and its fascia, where the pudendal (Alcock's) canal is located. The levator ani forms the medial wall and floor. The gluteus maximus lies posteriorly and laterally but is not the direct lateral boundary. The piriformis lies more superiorly at the greater sciatic foramen.
Reference: Gray's Anatomy, 42nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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