Vastus

Vastus is a group of muscles located in the anterior compartment of the thigh. The group is part of the quadriceps muscle, which is the large muscle at the front of the thigh. The vastus muscles are primarily responsible for extending the knee joint. The group consists of three individual muscles: the Vastus Lateralis, the Vastus Medialis, and the Vastus Intermedius.

Anatomy

The vastus muscles originate from different areas of the femur, the large bone in the thigh. The Vastus Lateralis originates from the greater trochanter and lateral lip of the linea aspera of the femur. The Vastus Medialis originates from the medial lip of the linea aspera. The Vastus Intermedius originates from the anterior and lateral surfaces of the body of the femur.

All three muscles insert at the patella, or kneecap, via the quadriceps tendon. The quadriceps tendon then continues as the patellar ligament and inserts at the tibial tuberosity on the tibia, the large bone in the lower leg.

Function

The primary function of the vastus muscles is to extend the knee. They are also involved in stabilizing the patella and the knee joint during walking and running.

Clinical significance

Injury or disease of the vastus muscles can lead to pain and difficulty in extending the knee. Conditions such as Patellofemoral Pain Syndrome and Chondromalacia Patellae can be caused by an imbalance in the forces exerted by the vastus medialis and vastus lateralis on the patella.

See also

• Quadriceps Femoris
• Knee
• Thigh

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