The largest of the four extensors of the knee, on the outer side of the thigh
Vastus lateralis.
Anatomy · Muscles
Vastus lateralis
The outer head of the quadriceps
Lower limb · thigh, anterior compartment
Vastus lateralis is the large muscle on the outer side of the thigh, the bulkiest of the four quadriceps heads. It arises from the upper femur and inserts into the patella through the quadriceps tendon, extending the knee. It is supplied by the femoral nerve and is the usual injection site in infants.
How to spot them
- ▸Bulky muscle on the outer side of the thigh, alongside the iliotibial tract
- ▸Arises from the greater trochanter and the lateral lip of the linea aspera
- ▸One of the three 'vasti' arising from the femur, next to vastus intermedius and medialis
- ▸Ends on the outer side of the patella via the quadriceps tendon
What to know
The muscle usually used for injections in the thigh of infants and children
Vastus lateralis — the anterolateral thigh.
A muscle arising from the greater trochanter and the lateral lip of the linea aspera
Vastus lateralis.
The head of the quadriceps that lies beside the iliotibial tract
Vastus lateralis.
It inserts on the lateral border of the patella
Vastus lateralis.
A muscle supplied by the femoral nerve that acts only at the knee
Vastus lateralis.
Key ideas
- It is one of three vasti arising from the femur; only rectus femoris crosses the hip.
- The muscle's bulk and distance from major nerves and vessels make the anterolateral thigh the recommended site for injections in infants.
Quick-fire facts
- •Origin: greater trochanter, intertrochanteric line and lateral lip of the linea aspera.
- •Insertion: lateral border of the patella, via the quadriceps tendon.
- •Nerve supply: femoral nerve (L2–L4).
- •Action: extends the knee.
- •It is generally the largest of the four quadriceps heads.
- •Its fibres blend with the iliotibial tract on the outer thigh.
- •The anterolateral thigh is the standard injection site in infants.
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