Piriformis muscle
| Piriformis muscle |
|---|
|
| Scheme of the deep hip muscles |
| origin |
|
Facies pelvina of the sacrum ( Os sacrum ) and Incisura ischiadica major on the ischium ( Os ischii ) |
| approach |
| Greater trochanter on the thighbone ( femur ) |
| function |
| Outward rotation ( external rotation ), splaying ( abduction ) and stretching or guiding the thigh backwards ( extension or retroversion ) |
| Innervation |
| Sacral plexus |
| Spinal segments |
| L5-S1 |
The piriformis muscle ( Latin for "pear-shaped muscle") is a flat, pyramidal to pear-shaped skeletal muscle of the lower extremity , more precisely the deep layer of the hip muscles. It runs on the inside of the pelvis ( pelvis ) to the thighbone ( femur ).
In the ungulates the muscle is not developed.
course
The area of origin of the pear-shaped muscle is the lateral ( lateral ) inner surface ( facies pelvica ) of the sacrum ( os sacrum ), where it arises with several fleshy points from the bone between the four anterior sacral holes ( foramina sacralia anteriora I-IV ). Other fiber coatings originate from the upper ( superior ) edge of the large collection of the iliac line ( greater sciatic notch ) at the ischium ( ischium ).
From there it runs through the large ischial bone hole ( foramen ischiadicum majus ), which it divides and attaches to the inside of the tip ( apex ) of the large hillock ( greater trochanter ) of the thigh bone ( femur ). Its insertion tendon often unites with the tendons of the upper and lower twin muscles ( musculus gemellus superior and musculus gemellus inferior ) as well as the obturator internus muscle .
function
The pear-shaped muscle turns the thigh outwards while standing, spreads it to the side ( abduction ) and stretches it ( extension ) or leads it backwards ( retroversion ).
In predators , its tendon unites with that of the gluteus medius muscle , making the two muscles together into a pure hip extensor.
See also
literature
- W. Platzer: Pocket Atlas of Anatomy , Volume 1 - Musculoskeletal System . Thieme Verlag, Stuttgart 2005, ISBN 3-13-492009-3 , p. 126.
- Franz-Viktor Salomon: muscle tissue . In: Anatomy for veterinary medicine . Enke, Stuttgart 2004, ISBN 3-8304-1007-7 , pp. 147-234.