Which muscle extends the leg?

Which muscle extends the leg?

• A. Quadriceps femoris
• B. Hamstrings
• C. Sartorius
• D. Gracilis

Answer: (A)

Extending the leg happens at the knee, and the main muscle that accomplishes this is the quadriceps femoris. This large anterior thigh muscle has four heads—rectus femoris and three vastus muscles—that converge into the quadriceps tendon and pull on the patella. Through the patellar ligament, this force is transmitted to the tibia, straightening the knee. The hamstrings on the back of the thigh flex the knee, so they oppose extension. Sartorius and gracilis mainly assist with knee flexion and other thigh actions, not knee extension. So the quadriceps femoris is the muscle that extends the leg.

Extending the leg happens at the knee, and the main muscle that accomplishes this is the quadriceps femoris. This large anterior thigh muscle has four heads—rectus femoris and three vastus muscles—that converge into the quadriceps tendon and pull on the patella. Through the patellar ligament, this force is transmitted to the tibia, straightening the knee. The hamstrings on the back of the thigh flex the knee, so they oppose extension. Sartorius and gracilis mainly assist with knee flexion and other thigh actions, not knee extension. So the quadriceps femoris is the muscle that extends the leg.