Piriformis Piriformis

Piriformis

پنج شنبه, 17 بهمن 1398 ساعت 09:26
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Piriformis is a flat muscle and the most superficial muscle of the deep gluteal muscles. It is part of the lateral rotators of the hip (obturator internus, superior and inferior gemelli, quadratus femoris, obturator externus, and gluteus maximus). It leaves the pelvis through the greater sciatic notch, until its fixation reaches the superior margin of the greater trochanter.It has a pyramidal shape that lies almost parallel with the posterior margin of the gluteus medius.


Anatomy


Origin

  •  Anterior aspect of the sacrum at the level of about S2 through S4
  •  Sacrotuberous ligament
  •  Periphery of the greater sciatic notch


Insertion

  •  Superior and medial aspects of the greater trochanter.


Nerve

  •  Sacral plexus,5 and S1,2


Artery

  •  The arterial supply is from the inferior gluteal, superior gluteal and internal pudendal arteries, all branches of the internal iliac artery.


Function

  •  Lateral Rotation of the hip when it is extended (that is when in standing).
  •  Abduction of the hip when it is flexed.
  •  Aids slightly in tilting pelvis laterally.
  •  Also aids in tilting pelvis posteriorly by pulling the sacrum down towards the thigh.


Clinical relevance


The piriformis muscle can be used to locate the sciatic nerve. This nerve enters the gluteal region inferiorly to the piriformis. If the lateral rotators of the hip are tight they may exert pressure on the sciatic nerve, producing pain radiating into the lower extremity.This is known as Piriformis Syndrome.
Another importance of this muscle is that it divides the gluteal region into a superior and inferior part. Therefore, it determines the name of the vessels and nerves that supply the area (e.g. the superior gluteal nerve and vessels emerge superiorly to the piriformis, and the inferior gluteal nerve and vessels emerge inferiorly to the piriformis).

خواندن 331 دفعه آخرین ویرایش در پنج شنبه, 17 بهمن 1398 ساعت 09:57
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