Unit 3

Question 1

Gluteus Maximus

Answer 1

Origin: ilium posterior to posterior gluteal line; dorsal surface of sacrum and coccyx; and sacrotuberous ligament

Insertion: most fibers end in iliotibial tract, which inserts into lateral condyle of tibia; some fibers insert on gluteal tuberosity of femur

Innervation: inferior gluteal nerve (L5, S1, S2)

Action: extends hip joint between flexed and standing positions and assists in its lateral rotation; steadies thigh and assists in rising from sitting position

Question 2

Gluteus Medius

Answer 2

Origin: external surface of ilium between anterior and posterior gluteal lines

Insertion: lateral surface of greater trochanter of femur

Innervation: superior gluteal nerve (L4, L5, S1)

Action: abduct and anterior portions medially rotate hip joint; keep pelvis level when opposite limb is elevated

Question 3

Gluteus Minimus

Answer 3

Origin: external surface of ilium between anterior and inferior gluteal lines

Insertion: anterior surface of greater trochanter of femur

Innervation: superior gluteal nerve (L4, L5, S1)

Action: abduct and anterior portions medially rotate hip joint; keep pelvis level when opposite limb is elevated

Question 4

Tensor Fasciae Latae

Answer 4

Origin: anterior superior iliac spine; anterior part of iliac crest

Insertion: iliotibial tract, which attaches to lateral condyle of tibia

Innervation: superior gluteal nerve (L4, L5, S1)

Action: flexes hip joint; acts with gluteus Maximus to stabilize the extended knee joint

Question 5

Piriformis

Answer 5

Origin: anterior surface of 2nd-4th sacral segments; superior margin of greater sciatic notch and sacrotuberous ligament

Insertion: superior border of greater trochanter of femur

Innervation: branches of anterior rami of S1, S2

Action: laterally rotate extended hip joint; abduct flexed hip joint; steady femoral head in acetabulum (stabilizes hip joint)

Question 6

Obturator Internis

Answer 6

Origin: pelvic surface of ilium and ischium; obturator membrane

Insertion: medial surface of greater trochanter (trochanteric fossa) of femur

Innervation: nerve to obturator Internis (L5, S1)

Action: laterally rotate extended hip joint; abduct flexed hip joint; steady femoral head in acetabulum (stabilizes hip joint)

Question 7

Gemelli (superior and inferior)

Answer 7

Origin: superior - ischial spine
Inferior - ischial tuberosity

Insertion: medial surface of greater trochanter (trochanteric fossa) of femur

Innervation: superior - nerve to obturator internus (L5, S1)
Inferior - nerve to quadratus femoris (L5, S1)

Action: laterally rotate extended hip joint; abduct flexed hip joint; steady femoral head in acetabulum (stabilizes hip joint)

Question 8

Quadratus Femoris

Answer 8

Origin: lateral border of Ischial tuberosity

Insertion: quadrate tubercle on intertrochanteric crest of femur and area inferior to it

Innervation: nerve to quadratus femoris (L5, S1)

Action: laterally rotates hip joint; also pulls femoral head into acetabulum to stabilize hip joint/pelvis