Vastus

Vasti
Muscles of lower extremity
Details
Origin	Femur
Insertion	Quadriceps tendon
Artery	Femoral artery
Nerve	Femoral nerve
Actions	Extension of knee joint
Anatomical terms of muscle []

Vasti (plural of vastus) are the three separate skeletal muscles located in the thigh. The three muscles; vastus intermedius, lateralis and medialis are located in the middle, on the outside and inside of the thigh, respectively. Together with the rectus femoris muscle the vastus muscles form the quadriceps femoris muscle, a large fleshy mass which covers the front and sides of the femur.

The vastus intermedius arises from the front and lateral surfaces of the body of the femur in its upper two-thirds, sitting under the rectus femoris muscle and from the lower part of the lateral intermuscular septum. Its fibers end in a superficial aponeurosis, which forms the deep part of the quadriceps femoris tendon.

The vastus medialis and vastus intermedius appear to be inseparably united, but when the rectus femoris has been reflected a narrow interval will be observed extending upward from the medial border of the patella between the two muscles, and the separation may be continued as far as the lower part of the intertrochanteric line, where, however, the two muscles are frequently continuous.

The vastus lateralis is the largest and most powerful of the three vasti muscles. It arises from the several areas of the femur, including the upper part of the intertrochanteric line; the lower, anterior borders of the greater trochanter, to the outer border of the gluteal tuberosity, and the upper half of the outer border of the linea aspera. These form an aponeurosis, a broad flat tendon which covers the upper three-quarters of the muscle. From the inner surface of the aponeurosis, many muscle fibres originate. Some additional fibres arise from the tendon of the gluteus maximus muscle, and from the septum between the vastus lateralis and short head of the biceps femoris.