Insertion Tibial tuberosity Nerve Femoral nerve | Artery Femoral artery | |
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Origin Combined rectus femoris and vastus muscles Actions Knee extension; Hip flexion (Rectus femoris only) Latin Musculus quadriceps femoris | ||
The quadriceps femoris (/ˈkwɒdrᵻsɛps ˈfɛmərᵻs/) (Latin for "four-headed muscle of the femur"), also called simply the quadriceps, quadriceps extensor, or quads, is a large muscle group that includes the four prevailing muscles on the front of the thigh.
Contents
It is the great extensor muscle of the knee, forming a large fleshy mass which covers the front and sides of the femur.
Structure
It is subdivided into four separate portions or 'heads', which have received distinctive names:
All four parts of the quadriceps muscle ultimately insert into the tuberosity of the tibia. This is via the patella, where the quadriceps tendon becomes the patellar ligament, which then attaches to the tibia.
There is a fifth muscle of the quadriceps complex that is often forgotten and rarely taught called articularis genus.
In addition, recent 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.
Innervation
Femoral nerve (L2, L3, L4).
Function
All four quadriceps are powerful extensors of the knee joint. They are crucial in walking, running, jumping and squatting. Because 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.
Training
In strength training, the quadriceps are trained by several leg exercises. Effective exercises include the squat and leg press. The isolation movement (i.e. targets solely the quadriceps) is the leg extension exercise.
In body building communities, this muscle is colloquially referred to as the "leg triceps".
Etymology
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.