Quadriceps muscle.

There are four muscles present in the anterior compartment of thigh. Those four muscles provides stability to the knee joint and helps in extention of knee. 

Name of quadriceps muscles - 

1. Rectus femoris

a. Origin - From anterior inferior iliac spine and groove above brim of acetabulum.

b. Insertion - Base of patella. 

c. Nerve supply - Femoral nerve (L1, L2,          L3).

d. Action - Extension of knee.

2. Vastus lateralis

a. Origin - Upper part of intertrochanteric         line of femur.

b. Insertion - Lateral and upper border of        patella.

c. Nerve supply - Femoral nerve.

d. Action - Extention of knee.

3. Vastus medialis

a. Origin - Lower part of intertrochanteric         line of femur.

b. Insertion - Upper and medial border of        patella. 

c. Nerve supply - Femoral nerve. 

d. Action - Extention of knee. 

4. Vastus intermedius

a. Origin - Upper 2/3rd anterior and lateral      surfaces of shaft of femur

b. Insertion - Lateral border of patella.

c. Nerve supply - Femoral nerve. 

d. Action - Extention of knee.

NOTE - 

Vastus medialis has also two  parts

1. Vastus medialis longus(VML)

2. Vastus medialis oblique(VMO) 

VMO exercises are very helpful in knee pain specially in arthritis

VMO isometric contraction