The Posterior Compartment of the Thigh

Question 1

Explain the division of the obturator nerve.

Answer 1

The obturator nerve gives 2 divisions that arise just after the nerve traverses the obturator canal.
(a) The anterior division, giving an articular branch to the hip joint, descends in the thigh behind the adductor longus, which it supplies. Passing over the anterior surface of adductor brevis, which it supplies, it goes on to supply gracilis and ends in the sub-sartorial plexus, where branches supply the skin over the medial side of the thigh.

(b) The posterior division pierces obturator externus and then passes over adductor magnus. It supplies both of these muscles and gives articular branches that supply the capsule of the knee joint.

Note that only the pubofemoral (adductor part) of the adductor magnus is supplied by the obturator nerve. The ischiocondylar (hamstring) part is supplied by the tibial nerve.

Question 2

State the blood supply to:
a) Biceps femoris
b) Semimembranous
c) Semitendinosus

Answer 2

a) perforating branches of profunda femoris artery, inferior gluteal artery, and the medial circumflex femoral artery (MCFA)
b) perforating branches of profunda femoris artery, and MCFA
c) perforating branches of profunda femoris artery, and MCFA