Vastus medialis
Musculus vastus medialis
Also known as: VMO, vastus medialis obliquus, teardrop muscle
The teardrop-shaped medial part of the quadriceps. Its lowest, oblique fibres (VMO) resist lateral displacement of the patella during extension.
Overview
Vastus medialis arises from the lower intertrochanteric line, the spiral line, the medial lip of the linea aspera and the medial supracondylar line, and from the tendons of adductor longus and magnus. It inserts on the medial border of the patella and the quadriceps tendon, and sends an expansion to the medial patellar retinaculum. Its distal fibres, the vastus medialis obliquus (VMO), run almost horizontally and produce the visible "teardrop" above the medial knee. They are thought to stabilise the patella against lateral tracking, particularly in the last degrees of extension. Its upper part forms the anterolateral wall of the adductor canal.
Anatomy
- Origin
Intertrochanteric line, medial lip of the linea aspera, medial supracondylar line and the adductor tendons.
- Insertion
Medial border of the patella and the quadriceps tendon, then the tibial tuberosity via the patellar ligament.
- Action
Extension of the leg at the knee; medial stabilisation of the patella.
- Innervation
Femoral nerve.
- Nerve roots
L2–L4
- Arterial supply
Femoral and profunda femoris arteries; descending genicular artery.
- Relations
Forms the lateral wall of the adductor canal. Lies in front of the adductors and medial to vastus intermedius.
Function
- Extends the knee
- Stabilises the patella against lateral displacement (VMO)
Clinical significance
Patellofemoral pain and instability
Weakness of VMO, a wide Q angle, a high-riding patella or a shallow trochlea predispose to lateral patellar maltracking and dislocation, commonly in adolescent females. Rehabilitation emphasises quadriceps and hip strengthening.
Compiled from standard anatomy and physiology references — see the Muscular System sources. For education only; not medical advice.