Anatomy
Quadriceps, Sartorius and Kneecap
The quadriceps is the large muscle at the front of the thigh. With the kneecap it forms the system that straightens the knee and absorbs shock with every step, stair and jump.
- Rectus femoris
- Vastus lateralis
- Vastus medialis
- Sartorius
- Patella
Where is it?
The quadriceps combines rectus femoris, vastus lateralis, vastus medialis and vastus intermedius. Their tendons surround the kneecap and continue as the patellar tendon down to the shin bone. Sartorius, a long strap-like muscle, crosses the thigh diagonally toward the inner knee.
What does it do?
The quadriceps straightens the knee and controls bending when you go downstairs or squat. Rectus femoris also bends the hip. The kneecap increases the muscle’s leverage. Sartorius helps bend and rotate the hip and knee.
Common problems
Each problem has its own detailed page: symptoms, causes, treatment and when to seek care.
How we can help
When to seek care
Book an appointment if knee pain limits stairs, squatting or running. A very swollen knee after a twist, locking, inability to straighten the leg, or a hot red knee with fever needs prompt medical assessment.
Frequently asked questions
Other areas of the body
Educational content: it does not replace an assessment. Your therapist determines the cause of your symptoms in person.