Muscle
Vastus medialis
Medial quadriceps muscle supporting the extensor system
High-yield
It extends the knee and contributes to medial control of the patella. Patellar stability also depends on ligaments, joint shape and other muscle forces, so VMO action alone cannot guarantee against dislocation.
Overview
Vastus medialis follows the inner femur into the quadriceps tendon and medial patellar tissues. Its lower fibers run more obliquely and are often called VMO, although they are not always separated as a distinct muscle head.
Reference facts
- Origin
- Lower intertrochanteric region, medial linea aspera, upper medial supracondylar line and adjacent septal/tendinous attachments
- Insertion
- Medial patellar base and border, quadriceps tendon/aponeurosis and medial retinacular tissues; linked onward to the tibial tuberosity
- Action
- Extends the knee and contributes to the balance of forces guiding the patella
- Innervation
- Muscular branches of the femoral nerve, conventionally L2-L4
- Blood supply
- Femoral and profunda femoris branches, with descending and other genicular contributions around the knee
Clinical correlation
Weakness can be relevant when assessing knee function, but isolated VMO strengthening is not established as a universally superior approach. Rehabilitation decisions consider the broader extensor mechanism and the person's condition.
Frequently asked questions
What does the vastus medialis do?
The vastus medialis extends the knee and contributes to the balance of forces guiding the patella.
What nerve innervates the vastus medialis?
The vastus medialis is innervated by the muscular branches of the femoral nerve, conventionally L2-L4.
Where does the vastus medialis attach?
Origin: Lower intertrochanteric region, medial linea aspera, upper medial supracondylar line and adjacent septal/tendinous attachments. Insertion: Medial patellar base and border, quadriceps tendon/aponeurosis and medial retinacular tissues; linked onward to the tibial tuberosity.
What is the blood supply of the vastus medialis?
The vastus medialis is supplied by the femoral and profunda femoris branches, with descending and other genicular contributions around the knee.