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Piriformis

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Origin

  • Anterior surface of the Sacrum
  • Gluteal surface of Ilium
  • Sacrotuberous ligament

Insertion


Actions

  • External rotation of hip when in extension
  • Abduction of hip when in flexion
  • Stabilizes Femur in acetabulum

Vascular Supply

  • Superior Gluteal Artery
  • Inferior Gluteal Artery
  • Internal Pudendal Artery (gemellar branches)

Innervation

  • Piriformis Nerve (S1-S2)
    • Also referred to as 'nerve to piriformis'

Sciatic Nerve

  • Beaton et al cadaveric study[1]
    • 90% of cadavers had traditional anatomy with an undivided sciatic nerve emerging below the piriformis muscle
    • Divided sciatic nerve passing through and below the piriformis muscle
    • Divided sciatic nerve passing above and below the piriformis muscle
    • Undivided nerve passing through the piriformis muscle
  • Smoll et al systematic review and meta-analysis[2]
    • 16.9% of cadavers: abnormal relationship between the sciatic nerve and piriformis muscle
  • Bartet et al MRI study[3]
    • 19.2% of MRI revealed an abnormal relationship between the sciatic nerve and piriformis muscle

Clinical Significance


See Also


References


  1. Beaton LA, Anson BJ. The sciatic nerve and the piriformis muscle: their interrelation a possible cause of coccygodynia. J Bone Joint Surg. 1938;20(3):686‐688.
  2. Smoll NR. Variations of the piriformis and sciatic nerve with clinical consequence: a review. Clin Anat. 2010;23(1):8‐17.
  3. Bartret AL, Beaulieu CF, Lutz AM. Is it painful to be different? Sciatic nerve anatomical variants on MRI and their relationship to piriformis syndrome. Eur Radiol. 2018;28(11):4681‐4686.
Created by:
Chris Hauglid on 7 July 2020 18:28:55
Authors:
Last edited:
5 August 2020 15:09:34
Category: