Summary
Origins
- Straight head from the anterior inferior iliac spine of the 🦴 ilium
- Reflected head from the superior rim of the acetabulum and joint capsule
Insertions
- Quadriceps tendon to the 🦴 patella and via the patellar ligament to the tibial tuberosity
Actions
- Extends the knee via the quadriceps tendon
- Assists hip flexion when the thigh starts swinging forward
- Helps stabilize the patella within the trochlear groove
The rectus femoris is the only quadriceps head that crosses both hip and knee, so it powers knee extension while initiating hip flexion. Its long, central path frames the anterior thigh, and its tendinous edges hint at pelvic tilt.
Key Features
- Straight yet dynamic: The superficial tendon forms a crisp central line that angles slightly laterally before diving into the quadriceps tendon.
- Dual attachments: Separate straight and reflected heads originate from the anterior inferior iliac spine and the acetabular rim, creating a subtle "Y" seam at the pelvis.
- Interplay with neighbors: Overlaps the deep Vastus Intermedius and is flanked by Vastus Lateralis and Vastus Medialis, which soften its edges as the knee bends.
Drawing Tips
- Track the muscle as a flattened cylinder that broadens near the Patella before blending into the tendon.
- Pose choices that stretch the hip while flexing the knee will pop its tendinous borders; compressing both joints makes the surface appear flat.
- Echo the tendon rhythm through the thigh by aligning it with the Sartorius sweep and the Tensor Fasciae Latae tension along the iliotibial tract.