Question

Part 1:

Name the muscles that have collective responsibility of extending the knee. What nerve innervates each muscle?

Part 2:

Name the muscles that have collective responsibility of flexing the knee. What nerve innervates each muscle?

Answer 1

1 - Muscles that cause extension of knee are the QUADRICEPS FEMORIS muscle group, this group includes the following muscle -

• Rectus femoris,
• Vastus lateralis
• Vastus medius
• Vastus intermedius

This group is innervated by the femoral nerve (L2-L4).

2 - Muscles that cause the flexion of the knee are the HAMSTRING group of muscles, which includes -

• Semitendinosus
• Semimembranosus
• Biceps femoris

Hamstrings are innervated by the sciatic nerve, specifically by the main branch of it - the tibial nerve. The short head of the biceps femoris is innervated by the common fibular nerve.