Together with other muscles of the quadriceps group, it serves to extend the knee joint, moving the lower leg forward.

The vastus lateralis is the recommended site for intramuscular injection in infants less than 7 months old and those unable to walk, with loss of muscular tone.

Some additional fibers arise from the tendon of the gluteus maximus muscle, and from the septum between the vastus lateralis and short head of the biceps femoris.

The fibers form a large fleshy mass, attached to a second strong aponeurosis, placed on the deep surface of the lower part of the muscle.

This article incorporates text in the public domain from page 470 of the 20th edition of Gray's Anatomy (1918)