vastus Definition

vastus lateralis

the division of the quadriceps muscle that arises from and covers the front of the shaft of the femur

vastus medialis

the division of the quadriceps muscle that covers the outer anterior aspect of the femur, arises chiefly from the femur, and inserts into the outer border of the patella by a flat tendon which blends with that of the other divisions of the muscle and sends an expansion to the capsule of the knee —called also vastus externus

the division of the quadriceps muscle that covers the inner anterior aspect of the femur, arises chiefly from the femur and the adjacent intermuscular septum, inserts into the inner border of the patella and into the tendon of the other divisions of the muscle, sends also a tendinous expansion to the capsule of the knee joint, and is closely and in the upper part often inseparably united with the vastus intermedius —called also vastus internus