Overview
Its four heads converge on the patella: rectus femoris, vastus lateralis, vastus medialis and vastus intermedius. The model shows the first three; the vastus intermedius lies deep, on the cranial surface of the femur.
Origin
- Rectus femoris (m. rectus femoris): body of the ilium, cranial to the acetabulum. The only head that crosses the hip.
- Vasti (m. vastus lateralis, medialis, intermedius): proximal femur.
Insertion
Tibial tuberosity, through the patella and the patellar ligament.
Action
Extends the stifle. The rectus femoris also flexes the hip.
Innervation
Femoral nerve (n. femoralis).
Clinical relevance
- Tapping the patellar ligament extends the stifle: the patellar reflex tests the femoral nerve and spinal cord segments L4–L6.
- Its craniolateral part is, together with the lumbar epaxial muscles, the preferred site for intramuscular injections in the cat.
- In medial patellar luxation, which in the cat is often bilateral and is described in breeds such as the Devon Rex and the Abyssinian, the pull of the quadriceps is displaced medially.