Vastus intermedius
Musculus vastus intermedius
Also known as: articularis genus, vastus medius
The deepest part of the quadriceps, lying on the anterior femoral shaft beneath rectus femoris. It extends the knee, and its deep slip (articularis genus) retracts the suprapatellar bursa.
Overview
Vastus intermedius arises from the upper two-thirds of the anterior and lateral surfaces of the femoral shaft and the lateral intermuscular septum. It lies between vastus lateralis and medialis and deep to rectus femoris. Its aponeurosis forms the deep layer of the quadriceps tendon. A few deep distal fibres form the small articularis genus muscle, which pulls the synovial suprapatellar bursa upward during extension so it is not trapped between the patella and femur.
Anatomy
- Origin
Anterior and lateral surfaces of the femoral shaft (upper two-thirds).
- Insertion
Deep surface of the quadriceps tendon and the base of the patella, then the tibial tuberosity via the patellar ligament.
- Action
Extension of the leg at the knee.
- Innervation
Femoral nerve.
- Nerve roots
L2–L4
- Arterial supply
Lateral circumflex femoral artery and profunda femoris branches.
Function
- Extends the knee
- Retracts the suprapatellar bursa (articularis genus)
Clinical significance
Thigh contusion ("dead leg")
A direct blow crushes vastus intermedius against the femur. A large haematoma can lead to myositis ossificans.
Compiled from standard anatomy and physiology references — see the Muscular System sources. For education only; not medical advice.