Muscles of Posterior Thigh: Extensors of Hip and Flexors of Knee

Question 1

Biceps Femoris

Answer 1

O: Long Head- Ischial Tuberosity
Short Head- Linea Aspera and Lateral Supracondylar Line
I: Lateral side of head of fibula; Tendon is split there by Fibular Collateral Ligament
N: Long Head- Tibial Nerve
Short Head- Common Peroneal Nerve
L5 S1 S2
A: 1. Flexes Leg
2. Rotates leg laterally when knee is flexed
3. Extends thigh

Question 2

Semitendinosus

Answer 2

O- Ischial tuberosity
I- Medial surface of superior part of tibia
N- Tibial Nerve L5 S1 S2
A: 1. Extend thigh
2. Flex leg when knee is flexed
3. Rotate leg medially when knee is flexed
4. When thigh and leg are flexed, can extend trunk

Question 3

Semimembranosis

Answer 3

O- Ischial Tuberosity
I- Posterior part of medial condyle of tibia; Reflected attachment forms Oblique Popliteal Ligament
N- Tibial Nerve L5 S1 S2
A: 1. Extend thigh
2. Flex leg when knee is flexed
3. Rotate leg medially when knee is flexed
4. When thigh and leg are flexed, can extend trunk