Anomaly of bilateral persistent sciatic arteries.

A pair of persistent sciatic arteries was encountered in the body of a 91-year-old Japanese woman in the course of an ordinary dissection at Nara Medical University. The artery of each side followed nearly the same course in the posterior aspect of the thigh; after leaving the pelvis through the infrapiriform foramen, the persistent sciatic artery was observed descending between the tibial and common peroneal nerves, accompanied by the sciatic vein. In the popliteal fossa, the persistent sciatic artery ended by joining the popliteal artery. The sciatic nerves on both sides were found to have divided, while in the pelvis, into the tibial and the common peroneal nerves; the former passed through the infrapiriform foramen, while the latter perforated the piriformis muscle to reach the posterior aspect of the upper thigh.