Lecture 20, Posterior/Lateral Muscles and Hamstrings

Question 1

Gluteus maximus

Answer 1

extends hip joint between flexed and standing positions and assists in its lateral rotation; steadies thigh and assists in rising from sitting position (inferior gluteal nerve)

Question 2

Gluteus medius

Answer 2

abduct and anterior portions medially rotate hip joint; keep pelvis level when opposite limb elevated (superior gluteal nerve)

Question 3

Gluteus minimus

Answer 3

abduct and anterior portions medially rotate hip joint; keep pelvis level when opposite limb elevated (superior gluteal nerve)

Question 4

Tensor fasciae latae (tensor of fascia lata)

Answer 4

flexes hip joint; acts with gluteus maximus to stabilize the extended knee joint (superior gluteal nerve)

Question 5

Piriformis (passes through greater sciatic foramen)

Answer 5

laterally rotate extended hip joint; abduct flexed hip joint; steady femoral head in acetabulum (stabilizes hip joint) (branches of anterior rami of S1, S2)

Question 6

Obturator internus (passes through lesser sciatic foramen)

Answer 6

laterally rotate extended hip joint; abduct flexed hip joint; steady femoral head in acetabulum (stabilizes hip joint) (nerve to obturator internus)

Question 7

Gemelli, superior and inferior

Answer 7

laterally rotate extended hip joint; abduct flexed hip joint; steady femoral head in acetabulum (stabilizes hip joint) (superior: same as obturator internus/inferior: same as quadratus femoris)

Question 8

Quadratis femoris

Answer 8

laterally rotates hip joint; also pulls femoral head into acetabulum to stabilize hip joint/pelvis (nerve to quadratus femoris)

Question 9

Semitendinosus & Semimembranosus

Answer 9

extend hip joint; flex knee joint and rotate the leg medially when the knee is flexed; when hip and knee are flexed, can extend trunk (tibial division of sciatic nerve)

Question 10

Biceps femoris: long head and short head

Answer 10

flexes knee joint and rotates it laterally when knee is flexed; extends hip joint
long head - tibial division of sciatic nerve
short head - common fibular nerve