Question

During leg extension and flexion which nerves are being used?

		Superior gluteal and femoral
		Tibial component of sciatic and ulnar
		Femoral and tibial component of sciatic
		Inferior gluteal and sciatic

Answer 1

Answer is option (c) femoral and tibial component of sciatic nerve

Extension of leg at the knee joint is carried out by extensor group of muscles.
They are located in the anterior compartment of thigh.
There are group of 4 muscles called quadriceps femoris which takes part in the extension of leg at knee joint.
4 muscles include rectus femoris,vastus lateralis, vastus medialis, and vastus intermedius.
All these muscles are innervated by posterior branch of femoral nerve.

Flexion or bending the knee is a result of contraction of group of muscles.
They are biceps femoris, semimembranosus, semitendinosus, gracilis, gastrocnemius, sartorius and popliteus.
These muscles are situated in the posterior compartment of leg.
Nerve innervation to these muscles come from sciatic nerve.
Sciatic nerve divides into tibial nerve and common peroneal nerve in the popliteal fossa.
Tibial never travels down the posterior compartment of leg into the foot and innervated the muscles there which are responsible for leg flexion.