Quadriceps femoris muscle

Origin: Combined rectus femoris and vastus muscles

Insertion: Patella and Tibial tuberosity via the Patellar ligament

Artery: Femoral artery

Nerve: Femoral nerve

Action: Knee extension; Hip flexion (R.Fem. only)

Antagonist: Hamstring

Description:
The Quadriceps femoris (Quadriceps extensor) includes the four remaining muscles on the front of the thigh. It is the great extensor muscle of the leg, forming a large fleshy mass which covers the front and sides of the femur. It is subdivided into separate portions, which have received distinctive names. One occupying the middle of the thigh, and connected above with the ilium, is called from its straight course the Rectus femoris. The other three lie in immediate connection with the body of the femur, which they cover from the trochanters to the condyles. The portion on the lateral side of the femur is termed theVastus lateralis; that covering the medial side, the Vastus medialis; and that in front, theVastus intermedius.
The tendons of the different portions of the Quadriceps unite at the lower part of the thigh, so as to form a single strong tendon, which is inserted into the base of the patella, some few fibers passing over it to blend with the ligamentum patellae. More properly, the patella may be regarded as a sesamoid bone, developed in the tendon of the Quadriceps; and the ligamentum patellae, which is continued from the apex of the patella to the tuberosity of the tibia, as the proper tendon of insertion of the muscle, the medial and lateral patellar retinacula being expansions from its borders. A bursa, which usually communicates with the cavity of the knee-joint, is situated between the femur and the portion of the Quadriceps tendon above the patella; another is interposed between the tendon and the upper part of the front of the tibia; and a third, the prepatellar bursa, is placed over the patella itself.
Nerves.—The muscles of this region are supplied by the second, third, and fourth lumbar nerves, through the femoral nerve.
Actions: The Quadriceps femoris extends the leg upon the thigh. The Rectus femoris assists the Psoas major and Iliacus in supporting the pelvis and trunk upon the femur. It also assists in flexing the thigh on the pelvis, or if the thigh be fixed it will flex the pelvis. The Vastus medialis draws the patella medialward as well as upward.