The structure indicated is the vastus lateralis

The vastus lateralis is one of the muscles that makes up the quadriceps femoris, and is contained in the anterior compartment of the thigh. The muscles of the anterior compartment are all innervated by the femoral nerve and serve generally to extend the leg at the knee joint.

The four muscles that make up the quadriceps femoris are the:

• Rectus femoris
• Vastus lateralis
• Vastus medialis
• Vastus intermedius

In addition to the quadriceps muscles, the Sartorius muscle is also located in the anterior compartment together with the distal ends of the iliopsoas muscles.

Origin: Superior half of anterior and lateral surfaces of femur

Insertion: lateral border of base of patella (then joins patella ligament to attach to tibial tuberosity)

Action: Extends the knee

Innervation: Femoral nerve

Learn more about the anatomy of the muscles of the thigh in this tutorial.