Vastus Lateralis

legsMusculus vastus lateralis

The vastus lateralis is the largest of the four quadriceps and sits on the outside of the thigh. It is the muscle that produces the outward sweep of a developed leg.

Vastus Lateralis highlighted on an anatomical figure, from behind.
Where it sits, from behind.

Vastus lateralis is the biggest quadriceps muscle and the biggest single muscle of the thigh. It arises from the upper and outer part of the thigh bone and runs down and inward to the outer edge of the kneecap, wrapping around the outside of the leg on the way.

It crosses only the knee, so unlike rectus femoris its length does not change with hip position — it works the same way whatever the hip is doing.

It is the muscle responsible for the outward flare of the thigh above the knee, the shape people mean by the quad sweep. That outline is largely this one muscle.

It also pulls the kneecap outward as the knee straightens, which is balanced by the vastus medialis pulling inward. The two act as a pair to keep the kneecap tracking straight in its groove.

Training notes

Any knee extension trains it, and because of its size it takes the largest share of the load in most squatting and pressing. It is rarely the limiting muscle and rarely needs specific attention.

Squats, leg presses and hack squats all load it heavily. Leg presses with a lower foot position and hack squats put more of the work through the quads generally, and therefore through this muscle.

Its visible contribution to leg shape is larger than any other quadriceps muscle, which is worth knowing for anyone training legs for appearance rather than performance.

Anatomy

Origin
  • Greater trochanter, the intertrochanteric line and the lateral lip of the linea aspera of the femur
Insertion
  • Lateral border of the patella, through the quadriceps tendon
Actions
  • Extends the knee
  • Draws the patella laterally as the knee straightens
Innervation
Femoral nerve (L2–L4)

Exercises

Antagonists

Synergists