anatomy/quadriceps·Muscle
Quadriceps
Musculus quadriceps femoris
The four-headed thigh extensor. It straightens the knee when standing up, climbing stairs and in every squat.
// Structure & location
The quadriceps consists of four muscles at the front of the thigh: the rectus femoris in the middle, the vastus lateralis on the outside, the vastus medialis on the inside (the teardrop above the knee) and the vastus intermedius underneath. All four insert via the quadriceps tendon on the kneecap, which is connected to the tibia by the patellar tendon.
// Function
Together they extend and stabilise the knee, as in a kick, according to OpenStax. The rectus femoris arises from the pelvis and also flexes the hip. When landing from a jump they brake the knees from buckling.
// For training & sport
- Squats, leg press and lunges train all four heads.
- Leg extensions isolate it, including the rectus femoris.
- Deep squats challenge it in a longer, stretched position.
// Good to know
The kneecap acts like a pulley: it increases the distance between the tendon and the knee joint and therefore the leverage of the quadriceps.
// Sources
last reviewed: 2026-11-14
// More from the atlas: Muscles
Pectoralis majorDeltoidBicepsTricepsForearm musclesRectus abdominisObliquesSerratus anteriorHip flexorsAdductorsTibialis anteriorTrapeziusLatissimus dorsiErector spinaeGluteus maximusHamstringsCalves