|Quadriceps femoris muscle|
|Origin||Combined rectus femoris and vastus muscles|
|Actions||Knee extension; Hip flexion (Rectus femoris only)|
|Latin||Musculus quadriceps femoris|
|Anatomical terms of muscle|
The quadriceps femoris (, also called the quadriceps extensor, quadriceps or quads) is a large muscle group that includes the four prevailing muscles on the front of the thigh.
It is subdivided into four separate muscles (the 'heads'):
The rectus femoris arises from the anterior inferior iliac spine and from the superior edge of the acetabulum. It is thus a biarticular muscle. The other parts of the quadriceps arise from the surface of the femur.
There is a small fifth muscle of the quadriceps complex called the articularis genus that is not often included.
In addition, cadaver studies have confirmed the presence of a sixth muscle, the tensor vastus intermedius. While the muscle has variable presentations, it consistently originates at the proximal femur, runs between the vastus lateralis and vastus intermedius muscles, and inserts distally at the medial aspect of the patellar base. Historically considered a part of the vastus lateralis, the tensor vastus intermedius muscle is innervated by an independent branch of the femoral nerve and its tendinous belly can be separated from the vasti lateralis and intermedius muscles in most cases.
Femoral nerve (L2, L3, L4).
All four quadriceps are powerful extensors of the knee joint. They are crucial in walking, running, jumping and squatting. Because the rectus femoris attaches to the ilium, it is also a flexor of the hip. This action is also crucial to walking or running as it swings the leg forward into the ensuing step. The quadriceps, specifically the vastus medialis, play the important role of stabilizing the patella and the knee joint during gait.
In strength training, the quadriceps are trained by several leg exercises. Effective exercises include the squat and leg press. The isolation movement (i.e. targeting solely the quadriceps) is the leg extension.
The proper Latin plural form of the adjective quadriceps would be quadricipites. In modern English usage, quadriceps is used in both singular and plural. The singular form quadricep, produced by back-formation, is frequently used.
The quadriceps tendon connects to the top part of the kneecap (patella)