Rectus femoris: origin, insertion, action and innervation
The rectus femoris arises from the anterior inferior iliac spine and above the acetabulum and inserts on the tibial tuberosity through the quadriceps tendon and patellar ligament. It extends the knee, flexes the hip and is supplied by the femoral nerve.
Quick answer
- Latin name
- Musculus rectus femoris
- Origin
- Straight head: anterior inferior iliac spine. Reflected head: ilium just above the acetabulum (hip bone)
- Insertion
- Base of the patella through the quadriceps tendon, then the tibial tuberosity of the tibia through the patellar ligament
- Action
- Extends the knee and flexes the hip
- Innervation
- Femoral nerve (L2–L4)
- Blood supply
- Lateral circumflex femoral artery
The rectus femoris is one of the four heads of the quadriceps femoris, with the vastus lateralis, vastus medialis and vastus intermedius. It's the only one of them that crosses the hip.
Where it is
It runs straight down the middle of the front of the thigh, superficial to the vastus intermedius, with the vastus lateralis and medialis on either side. Above, it sits between the sartorius and the tensor fasciae latae.
Origin and insertion
- Straight head: the anterior inferior iliac spine (AIIS).
- Reflected head: a groove on the ilium just above the acetabulum (the hip socket).
- Insertion: with the other quadriceps heads, into the quadriceps tendon on the base of the patella, which continues as the patellar ligament to the tibial tuberosity.
The patella is a sesamoid bone inside this tendon: it gives the quadriceps a better lever on the knee.
What it does
- Knee extension, with the rest of the quadriceps: standing up, climbing, kicking.
- Hip flexion: because it crosses the hip, it lifts the thigh, as in a kick or a high step.
Kicking a ball uses both actions at once.
Innervation and blood supply
The femoral nerve (L2–L4) supplies it, like the rest of the quadriceps. Blood comes mainly from the lateral circumflex femoral artery.
How to remember it
- Rectus = straight down the thigh.
- The "kicking muscle": flex the hip, extend the knee.
- Quadriceps = rectus femoris + three vasti.
Frequently asked questions
Is the rectus femoris part of the quadriceps?
Yes. The quadriceps femoris has four heads: rectus femoris, vastus lateralis, vastus medialis and vastus intermedius.
Where does the rectus femoris insert?
On the patella through the quadriceps tendon, and then on the tibial tuberosity through the patellar ligament.
Why does the rectus femoris flex the hip?
Because, unlike the three vasti, it starts on the pelvis and crosses the hip joint.