Synonyms
German name: Birnenförmiger Muskel
Definition
The musculus piriformis is a pear-shaped muscle that belongs to the deep hip muscles. It helps, among other things, the external rotation, the abduction and the backward leading of the leg.
Course of the musculus piriformis
The musculus piriformis originates from the inner surface of the os sacrum (sacrum), more precisely from the foramina sacralia anteriora (sacral holes) one to four. In addition, some fiber lines originate from: It then passes through the ischial ischial hole and begins at the femur, more precisely at the inner surface of the apex of the greater trochanter (tip of the great trochanteric mound). The muscles Musculi gemelli and Musculus obturator internus also meet at this point.
- The upper edge of the Incisura ischiadica major
- From the Ligamentum sacrotuberaleund
- The Articulatio sacroiliaca
The piriformis muscle runs in direct proximity to the exit point of the sciatic nerve from the inside of the pelvis to the back of the buttocks. In some individuals, the sciatic nerve even passes through the piriformis muscle, which favors the development of sciatic pain through this muscle. If the piriformis muscle shortens or thickens, for example due to incorrect or insufficient training or limited hip mobility due to joint problems, the sciatic nerve is compressed and either pressed against the bony pelvis or trapped in the muscle fibers.
This pressure on the sciatic nerve results in so-called pseudo-radicular pain, i.e. pain that is very similar to the symptoms of a herniated disc, but is not caused by a problem with the intervertebral discs. Pain that is caused by pressure of a thickened piriformis muscle on the sciatic nerve or the entrapment of nerve fibers in the thickened piriformis muscle is also called piriformis syndrome. Overloading or postural deformity can also trigger piriformis syndrome through an inflammatory reaction.
The inflammation of the piriformis muscle can lead to an accompanying inflammation of the surrounding tissue. Since the sciatic nerve is located close to the piriformis muscle, it can also be affected by this inflammatory reaction and transmit pain impulses to the brain. Stinging pain in the lumbar spine and deep buttocks can be symptoms, as well as long-lasting pain radiating into the leg of the affected side or a tingling sensation spreading over the buttocks and back of the thigh.
In severe cases, standing on tiptoes and heels may be restricted. Piriformis syndrome can cause pain when climbing stairs, cycling, jogging or lying on the affected side. Prolonged sitting can also lead to an increase in pain, because in a sitting position not only the piriformis muscle irritates the sciatic nerve, but also the body weight leads to additional compression of the sciatic nerve. The crossing of the legs while sitting additionally worsens the pain.