Vastus lateralis
Musculus vastus lateralis
Also known as: vastus externus
The largest part of the quadriceps, forming the lateral bulk of the thigh. It extends the knee and is a common site for intramuscular injection and muscle biopsy.
Overview
Vastus lateralis arises by a broad aponeurosis from the greater trochanter, the upper intertrochanteric line, the lateral margin of the gluteal tuberosity and the lateral lip of the linea aspera. Its fibres pass down and forward to the lateral border of the patella and the quadriceps tendon, and it sends an expansion to the lateral patellar retinaculum. It lies deep to the iliotibial tract. It pulls the patella slightly laterally, which vastus medialis balances. It is supplied by the femoral nerve. Because it is large, superficial and away from major neurovascular structures, its middle third on the anterolateral thigh is the preferred intramuscular injection site in infants and a standard site for muscle biopsy.
Anatomy
- Origin
Greater trochanter, intertrochanteric line, gluteal tuberosity and the lateral lip of the linea aspera of the femur.
- Insertion
Lateral border of the patella and the quadriceps tendon, then the tibial tuberosity via the patellar ligament.
- Action
Extension of the leg at the knee.
- Innervation
Femoral nerve.
- Nerve roots
L2–L4
- Arterial supply
Descending branch of the lateral circumflex femoral artery; perforating branches of the profunda femoris.
- Relations
Covered by the iliotibial tract. Lies lateral to vastus intermedius and rectus femoris.
Function
- Extends the knee
- Contributes a lateral pull on the patella
Clinical significance
Injection and biopsy site
Vastus lateralis is the recommended IM vaccination site in infants under ≈12 months and a standard site for diagnostic muscle biopsy (e.g. in suspected myopathy).
Compiled from standard anatomy and physiology references — see the Muscular System sources. For education only; not medical advice.