Muscles Of The Posterior Compartment Of The Thigh

Question 1

Muscles in the Posterior Compartment

Answer 1

Biceps femoris, semitendinosus and semimembranosus.

Question 2

Biceps Femoris Attachments

Answer 2

The long head originates from the ischial tuberosity of the pelvis. The short head originates from the linea aspera on posterior surface of the femur. Together, the heads form a tendon, which inserts into the head of the fibula.

Question 3

Biceps Femoris Actions

Answer 3

Main action is flexion at the knee. It also extends the thigh at the hip, and laterally rotates at the hip and knee.

Question 4

Biceps Femoris Innervation

Answer 4

Long head innervated by the tibial part of the sciatic nerve, whereas the short head is innervated by the common fibular part of the sciatic nerve.

Question 5

Semitendinosus Attachments

Answer 5

It originates from the ischial tuberosity of the pelvis, and attaches to the medial surface of the tibia.

Question 6

Semitendinosus Actions

Answer 6

Flexion of the leg at the knee joint. Extension of thigh at the hip. Medially rotates the thigh at the hip joint and the leg at the knee joint.

Question 7

Semitendinosus Innervation

Answer 7

Tibial part of the sciatic nerve.

Question 8

Semimembranosus Attachments

Answer 8

It originates from the ischial tuberosity, but does so more superiorly than the semitendinosus and biceps femoris. It attaches to the medial tibial condyle.

Question 9

Semimembranosus Actions

Answer 9

Flexion of the leg at the knee joint. Extension of thigh at the hip. Medially rotates the thigh at the hip joint and the leg at the knee joint.

Question 10

Semimembranosus Innervation

Answer 10

Tibial part of the sciatic nerve.