The Four Muscles Of Knee Extension

In a vertical jump, knee extension occurs almost simultaneously with hip extension. Knee extension is the movement of straightening the leg at the knee joint. The major muscle involved in knee extension is the Quadriceps femoris, which is a group of four muscles. These four separate muscles of the Quadriceps femoris are the Vastus lateralis, Vastus medialis, Vastus intermedius, and Rectus femoris. These muscles, along with synergists, work together to perform knee extension for a vertical jump. Each of the muscles of the Quadriceps femoris have different origins, however they all share a common insertion on the tibial tuberosity through the patellar tendon. The Rectus femoris is located on the anterior aspect of the thigh and originates from the anterior inferior iliac spine. Contraction of the Rectus femoris muscle flexes the hips and extends the knee. The Vastus lateralis is on the lateral aspect of the thigh and originates from the lateral aspect of the femur. Originating from the medial aspect of the femur and found on the medial aspect of the thigh is the Vastus medialis muscle. The Vastus intermedius muscle is found deep to the Rectus femoris and originates from the anterior surface of the femur.
The Sartorius and Biceps femoris are synergists of the Rectus femoris. As the body lowers, the hips and knees undergo flexion, the ankle dorsiflexes and muscles around the joint contract. Tension is taken from the hamstrings when the knees slide forward during the squat. The hip extensors work in a vertical jump to extend the hip after the initial squat. These muscles include the Gluteus maximus and the hamstrings. The hamstrings are two-joint muscles. In addition to extending the hip, they work to bend the