Posterior Muscles

Question 1

Gluteus Maximum

Answer 1

Origin: dorsal ilium, sacrum, and coccyx and sacrotuberous ligament
Insertion: gluteal tuberosity of femur; iliotibial tract
Action: Major extensor of thigh, laterally rotates, abducts thigh
Innervated by the inferior gluteal nerve L5,S1,S2

Question 2

Gluteus Medius

Answer 2

Origin: Between anterior and posterior gluteal lines on lateral surface of ilium
Insertion: by short tendon into lateral aspect of greater trochanter of femur
Action: anterior fibers abducts and medially rotates thigh; posterior fibers extend and laterally rotate thigh
Innervated by the superior gluteal nerve

Question 3

Gluteus Minimus

Answer 3

Origin: between anterior and inferior gluteal lines on external surface of ilium
Insertion: anterior border of greater trochanter of femur
Action: anterior fibers abducts and medially rotates thigh; posterior fibers extend and laterally rotate thigh
Innervated by the superior gluteal nerve

Question 4

Piriformis (Lateral Rotators)

Answer 4

Origin: Anterior surface of sacrum
Insertion: superior border of greater trochanter of femur
Action: Rotates thigh laterally, abducts thigh
Innervated by the L5, S1, and S2

Question 5

Obturator Internus

Answer 5

Origin: Inner surface of obturator membrane, greater sciatic notch, and margins of obturator foramen
Insertion: Greater trochanter of femur in front of piriformis between superior gemellus and inferior gemellus
Action: Rotates thigh laterally, abducts thigh
Innervated by L5 and S1

Question 6

Gemellus Superior and Inferior

Answer 6

Origin: Ischial spine (superior), ischial tuberosity (inferior)
Insertion: greater trochanter of femur
Action: Rotates thigh laterally, abducts thigh
Innervated by L5 and S1

Question 7

Quadratus Femoris

Answer 7

Origin: Ischial tuberosity
Insertion: Intertrochanteric crest of femur
Action: Rotates thigh laterally and stabilizes hip joint
Innervated by L5 and S1

Question 8

Obturator Externus

Answer 8

Origin: Outer surface of obturator membrane, pubis, and ischium, margins of obturator foramen
Insertion: by a tendon into trochanteric fossa of posterior femur
Action: Rotates thigh laterally, abducts thigh
Innervated by the obturator nerve