Vastus lateralis muscle

At a glance

English

Vastus lateralis muscle

Latin (TA2)

Musculus vastus lateralis

System

Muscle

Region

Lower limb

Side

Paired, left and right

About the vastus lateralis muscle

Vastus lateralis is the biggest of the four heads of quadriceps femoris and makes up most of the fleshy outer side of the thigh. It lies under the iliotibial tract, which runs over it, and wraps around the outer side of the femur from the hip to just above the knee. It is the most common site for intramuscular injections in the thigh and for muscle biopsy, because no large nerves or vessels cross it superficially.

Its origin is a long, narrow line on the femur: the upper intertrochanteric line, the front and lower borders of the greater trochanter, the lateral side of the gluteal tuberosity and the upper half of the lateral lip of the linea aspera. It also takes fibres from the lateral intermuscular septum. The broad aponeurosis on its deep surface gives way to a tendon that joins the quadriceps tendon at the lateral border of the patella. Some fibres continue past the patella as the lateral patellar retinaculum to the lateral tibial condyle.

Like the other vasti it crosses only the knee and is a powerful extensor of that joint, needed for walking, running, jumping and rising from a squat. Its pull is directed slightly outwards, so it tends to draw the patella laterally. The lowest fibres of vastus medialis balance this, and an imbalance between the two is thought to contribute to pain at the front of the knee and to the kneecap slipping out of place.

It is supplied by the femoral nerve, through a branch running with the descending branch of the lateral circumflex femoral artery, which is its main blood supply. A small sixth head, the tensor of vastus intermedius, is sometimes described running between vastus lateralis and vastus intermedius to the patella. Heavy blows to the side of the thigh in contact sports commonly bruise this muscle.

Attachments, action and supply

Origin

Upper intertrochanteric line, greater trochanter, lateral gluteal tuberosity and upper lateral lip of the linea aspera, with the lateral intermuscular septum.

Insertion

Lateral border and base of the patella through the quadriceps tendon, and thence the tibial tuberosity; fibres also form the lateral patellar retinaculum.

Action

Extends the knee; tends to draw the patella laterally.

Nerve supply

Femoral nerve (L2, L3, L4).

Blood supply

Descending branch of the lateral circumflex femoral artery, with perforating branches of the deep femoral artery.