MSK - Deep Muscles of the Gluteal Region

Question 1

Name the 4 muscles of the deep gluteal region

Answer 1

• Piriformis
• Obturator Internus
• The Gemelli (superior and inferior)
• Quadratus Femoris

Question 2

What are the general actions of the deep gluteal muscles?

Answer 2

• Lateral rotation of the lower limb

- Stabilisation of the hip by pulling the femoral head into the acetabulum of the pelvis

Question 3

What is the origin of piriformis?

Answer 3

Anterior surface of the sacrum

Question 4

Where does piriformis insert?

Answer 4

Greater trochanter of the femur (after travelling infero-laterally through the greater sciatic foramen)

Question 5

What is the innervation of piriformis?

Answer 5

Nerve to piriformis (L5, S1, S2)

Question 6

What is the arterial supply of piriformis?

Answer 6

• Inferior and superior gluteal arteries

- Lateral sacral artery

Question 7

What are the actions of piriformis?

Answer 7

• Lateral rotation of the lower limb

- Abduction

Question 8

What is the origin of obturator internus?

Answer 8

Pubis and ischium at the obturator foramen

Question 9

Where does obturator internus insert?

Answer 9

Greater trochanter of the femur (after travelling through the lesser sciatic foramen)

Question 10

What is the innervation of obturator internus?

Answer 10

Nerve to obturator internus (L5, S1, S2)

Question 11

What is the arterial supply of obturator internus?

Answer 11

Inferior gluteal artery

Question 12

What are the actions of obturator internus?

Answer 12

• Lateral rotation of the lower limb

- Abduction

Question 13

What separates the two gemelli muscles?

Answer 13

Obturator internus tendon

Question 14

What is the origin of the superior gemellus muscle?

Answer 14

Ischial spine

Question 15

What is the origin of the inferior gemellus muscle?

Answer 15

Ischial tuberosity

Question 16

Where do both gemelli muscles insert?

Answer 16

Greater trochanter

Question 17

What is the innervation of the gemelli muscles?

Answer 17

• Superior = Nerve to obturator internus

- Inferior = Nerve to quadratus femoris

Question 18

What is the arterial supply of the gemelli muscles?

Answer 18

• Superior = Inferior gluteal artery

- Inferior = Inferior gluteal artery

Question 19

What are the actions of the gemelli muscles?

Answer 19

• Lateral rotation of the lower limb

- Abduction

Question 20

What is the origin of quadratus femoris?

Answer 20

Lateral side of the ischial tuberosity

Question 21

Where does quadratus femoris insert?

Answer 21

Quadrate tuberosity on the intertochanteric crest

Question 22

What is the innervation of quadratus femoris?

Answer 22

Nerve to quadratus femoris (L4-S1)

Question 23

What is the arterial supply of quadratus femoris?

Answer 23

Inferior gluteal artery

Question 24

What are the actions of quadratus femoris?

Answer 24

Lateral rotation of the lower limb

Question 25

Why is the piriformis muscle an important anatomical landmark?

Answer 25

• 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)