What is the main action of the gastrocnemius muscle?

The gastrocnemius muscle, one of the major muscles of the calf, primarily performs two important actions: it plantar flexes the foot and flexes the knee. When the gastrocnemius contracts, it pushes the heel down and raises the front of the foot, which is the action of plantar flexion. This motion is essential for various activities such as walking, running, and jumping, where powerful propulsion from the foot is required.

Additionally, the gastrocnemius also plays a role in flexing the knee when the leg is bent, making it a biarticular muscle as it crosses both the knee and ankle joints. This dual functionality is crucial for coordinated movement and stability during lower extremity activities. Hence, the correct answer captures both primary roles of the gastrocnemius in muscle movement.