Accessory belly of piriformis, as a cause of superior gluteal neurovascular entrapment

Rimple Bansal, Subhash Kaushal, Usha Chhabra


During routine dissection on 50 years old male cadaver, an accessory belly of piriformis was observed. This accessory belly was superior and parallel to the main piriformis muscle. This was associated with emergence of superior gluteal nerve and superior gluteal artery between the two bellies. Piriformis muscle    and its relation to sciatic nerve has been suggested as a cause of piriformis syndrome. But interestingly in the present case, superior gluteal nerve was interposed between two bellies that may help the clinicians to establish a rare yet important cause of piriformis syndrome and a rare cause of undiagnosed chronic pain in gluteal region. As superior gluteal artery was also interposed, so this rare variation holds interest to surgeons especially in isolated buttock claudication despite otherwise normal vascular investigations.


Anatomical muscle variation, Accessory piriformis muscle, Isolated buttock claudication, Piriformis syndrome, Superior gluteal nerve entrapment

Full Text:



Williams A, Newell RLM. Pelvic girdle, gluteal region and hip joint. In: Standring S. Gray’s Anatomy. The anatomical basis of clinical practice, Elsevier Churchill Livingstone, 39th Edition;2004:1419.

Russell JM, Krausderl MJ, Bancraft LW, Peterson JJ, Berquist TH, Bridges MD. Magnetic resonance imaging of the sacral plexus and piriformis muscles. Skeletal Radiol 2008;37:709-13.

Anson BJ, Mcvay CB. Surgical Anatomy, WB Saunders Company/ Philadelphia London Toronto, 5th Edition;1971:1087-8.

Diop M, Parratte B, Tatu L, Vuillier F, Faure A, Monnier G. Anatomical bases of superior gluteal nerve entrapment syndrome in the suprapiriformis foramen. Surg Radiol Anat 2002;24:155-9.

Yadav Y, Mehta V, Roy S, Suri S, Rath G. Superior gluteal nerve entrapment between two bellies of piriformis muscle. IJAV 2010;3:203-4.

Moore KL, Dalley AF. Lower limb. In clinical oriented anatomy, Lippincott Williams & Wilkins, 5th Edition; 2006:624.

Batt M, Desjardin T, Rogupoutos A, Hassen-Khodja, Le Bas. Buttock claudication from isolated stenosis of gluteal artery. J Vasc Surg 1997;25:584-6.