MSK - Deep Muscles of the Gluteal Region Flashcards
Name the 4 muscles of the deep gluteal region
- Piriformis
- Obturator Internus
- The Gemelli (superior and inferior)
- Quadratus Femoris
What are the general actions of the deep gluteal muscles?
- Lateral rotation of the lower limb
- Stabilisation of the hip by pulling the femoral head into the acetabulum of the pelvis
What is the origin of piriformis?
Anterior surface of the sacrum
Where does piriformis insert?
Greater trochanter of the femur (after travelling infero-laterally through the greater sciatic foramen)
What is the innervation of piriformis?
Nerve to piriformis (L5, S1, S2)
What is the arterial supply of piriformis?
- Inferior and superior gluteal arteries
- Lateral sacral artery
What are the actions of piriformis?
- Lateral rotation of the lower limb
- Abduction
What is the origin of obturator internus?
Pubis and ischium at the obturator foramen
Where does obturator internus insert?
Greater trochanter of the femur (after travelling through the lesser sciatic foramen)
What is the innervation of obturator internus?
Nerve to obturator internus (L5, S1, S2)
What is the arterial supply of obturator internus?
Inferior gluteal artery
What are the actions of obturator internus?
- Lateral rotation of the lower limb
- Abduction
What separates the two gemelli muscles?
Obturator internus tendon
What is the origin of the superior gemellus muscle?
Ischial spine
What is the origin of the inferior gemellus muscle?
Ischial tuberosity
Where do both gemelli muscles insert?
Greater trochanter
What is the innervation of the gemelli muscles?
- Superior = Nerve to obturator internus
- Inferior = Nerve to quadratus femoris
What is the arterial supply of the gemelli muscles?
- Superior = Inferior gluteal artery
- Inferior = Inferior gluteal artery
What are the actions of the gemelli muscles?
- Lateral rotation of the lower limb
- Abduction
What is the origin of quadratus femoris?
Lateral side of the ischial tuberosity
Where does quadratus femoris insert?
Quadrate tuberosity on the intertochanteric crest
What is the innervation of quadratus femoris?
Nerve to quadratus femoris (L4-S1)
What is the arterial supply of quadratus femoris?
Inferior gluteal artery
What are the actions of quadratus femoris?
Lateral rotation of the lower limb
Why is the piriformis muscle an important anatomical landmark?
- Divides gluteal region into inferior and superior segments by travelling through the greater sciatic foramen
- Superior gluteal nerve etc. = superior to piriformis
- Inferior gluteal nerve etc. = inferior to piriformis
- Also used to locate the sciatic nerve (directly inferior to piriformis)
