American Board of Surgical Assistants (ABSA) Orthopedic Practice Test

Which type of muscle is primarily involved in plantar flexion?

1. Gastrocnemius

2. Quadriceps

3. Hamstrings

4. Gluteus maximus

The correct answer is: Gastrocnemius

The gastrocnemius muscle is primarily responsible for plantar flexion, which is the movement that points the toes downward, away from the shin. This muscle, located in the calf, plays a crucial role in activities such as walking, running, and jumping by enabling the foot to push off the ground. Its anatomy allows it to effectively generate the necessary force for this action, particularly during propulsion phases of movement. In contrast, the quadriceps are primarily involved in knee extension rather than movement of the ankle. The hamstrings are more associated with flexion of the knee and hip extension, while the gluteus maximus primarily facilitates hip extension and outward rotation of the thigh. Thus, the distinct functional roles of these muscles highlight why the gastrocnemius is the key muscle for plantar flexion.