The two unite at an acute angle and spread into an aponeurosis that is prolonged downward on the anterior surface of the muscle, and from this the muscular fibers arise.

The muscle ends in a broad and thick aponeurosis that occupies the lower two-thirds of its posterior surface, and, gradually becoming narrowed into a flattened tendon, is inserted into the base of the patella.

The neurons for voluntary thigh contraction originate near the summit of the medial side of the precentral gyrus (the primary motor area of the brain).

When the rectus femoris receives the signal that has traveled all the way from the medial side of the precentral gyrus, it contracts, extending the knee and flexing the thigh at the hip.

The injury is caused by a forceful movement related to sprinting, jumping, or kicking and is common in sports like football or soccer.

Symptoms include a sudden sharp pain at the front of the hip or in the groin, swelling and bruising, and an inability to contract the rectus femoris with a full tear.