Quadriceps femoris muscle

Quadriceps femoris muscle is a large muscle group that includes the four prevailing muscles on the front of the thigh. It is the great extensor muscle of the knee, forming a large fleshy mass which covers the front and sides of the femur.

Anatomy

The quadriceps femoris muscle consists of four muscles located in the anterior compartment of the thigh. These muscles include the vastus lateralis, vastus medialis, vastus intermedius, and the rectus femoris. Each of these muscles originates in a different location but all share a common insertion point at the patella via the quadriceps tendon.

Vastus Lateralis

The vastus lateralis originates from the greater trochanter and lateral lip of the linea aspera of the femur. It is the largest and most powerful part of the quadriceps femoris.

Vastus Medialis

The vastus medialis originates from the medial side of the femur. It extends and stabilizes the knee.

Vastus Intermedius

The vastus intermedius originates from the anterior and lateral surfaces of the body of the femur in its upper two-thirds. It lies beneath the rectus femoris and is the deepest part of the quadriceps femoris.

Rectus Femoris

The rectus femoris originates from the anterior inferior iliac spine and the exterior surface of the bony ridge which forms the groove on the iliac portion of the acetabulum. Unlike the other muscles, it crosses two joints, the hip and knee, and is thus involved in two sets of actions.

Function

The primary function of the quadriceps femoris is to extend and stabilize the knee. It is crucial for walking, running, jumping and squatting. The rectus femoris, due to its origin at the hip, also serves to flex the hip joint.

Clinical Significance

Injury or strain to the quadriceps femoris can result in conditions such as quadriceps tendonitis, quadriceps contusion, and quadriceps strain. Rehabilitation exercises and physical therapy are often recommended for treatment.