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quadriceps femoris muscle
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Illustration of the human leg from the front showing major muscles, tendons, and ligaments of the thigh and lower leg, each labeled for anatomical reference.
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Diagram showing the anterior view of human leg muscles, highlighting the rectus femoris muscle as a bipennate fibred muscle, the extensor digitorum longus as a unipennate fibred muscle, and the tibialis anterior muscle as a parallel fibred muscle, with muscle fibers and tendons labeled. The Human Body Diagram showing the knee jerk reflex: a reflex hammer strikes the patellar tendon below the knee, activating a stretch receptor in the quadriceps muscle. This sends a signal through a sensory neuron to the spinal cord, where it connects to a motor neuron. The motor neuron then signals the muscle to contract, causing the lower leg to kick forward. The diagram also illustrates the pathway of sensory and motor neurons and their connection in the spinal cord.
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Illustration of the human leg from the front showing major muscles, tendons, and ligaments of the thigh and lower leg, each labeled for anatomical reference.
Muscles of the human leg Anterior view of the muscles of the human leg.

quadriceps femoris muscle

anatomy
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Diagram showing the anterior view of human leg muscles, highlighting the rectus femoris muscle as a bipennate fibred muscle, the extensor digitorum longus as a unipennate fibred muscle, and the tibialis anterior muscle as a parallel fibred muscle, with muscle fibers and tendons labeled.
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anterior view of human leg musclesAn anterior view of human leg muscles, showing the rectus femoris muscle (bipennate fibred muscle), the extensor digitorum longus (unipennate fibred muscle), and the tibialis anterior muscle (parallel fibred muscle).

quadriceps femoris muscle, large fleshy muscle group covering the front and sides of the thigh. It has four parts: rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. They originate at the ilium (upper part of the pelvis, or hipbone) and femur (thighbone), come together in a tendon surrounding the patella (kneecap), and insert at (are attached to) the tibia (shinbone). These muscles extend the legs at the knee and are important for standing, walking, and almost all activities involving the legs.

The Editors of Encyclopaedia Britannica This article was most recently revised and updated by Michele Metych.