Lots of people hold tension in the muscle in the buttock region that can cause pain. Piriformis syndrome my also be a cause of buttock pain. The piriformis muscle attaches to the front of the sacrum (the triangle shaped bone in the center of the low back) and inserts on the top of the femur or the hip bone. This muscle easily gets irritated both by problems in the hip and low back area. Also, the sciatic nerve either passes over this muscle under this muscle or even trough the muscle depending on your anatomy. So, if you have any irritation to the sciatic nerve, hip, sacrum or low back this can cause spasm and pain in the piriformis muscle. So don't forget to release the piriformis.

See the Low Back section for exercises for the buttock.