The piriformis muscle is situated in the buttock near to the hip joint. Piriformis syndrome is a condition in which this muscle can develop spasm or trigger points and cause buttock pain and pain referring down the back of the leg.
Spasm in the piriformis muscle can also irritate the sciatic nerve which lies close to it and even sometimes passes through the muscle. This can cause pain, numbness and tingling along the back of the leg and into the foot.
Piriformis syndrome is discussed in considerable detail on the Spine-Health website via this link.
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Pain Service Website, Gloucestershire Hospitals NHS Foundation Trust
Webmaster Dr J G de Courcy, Consultant in Pain Medicine and Anaesthesia
Page updated 22/6/2016