Which muscle is NOT involved in plantarflexion?

The muscle that is not involved in plantarflexion is the tibialis anterior. This muscle is primarily responsible for dorsiflexion of the foot, which means it raises the foot upwards towards the shin. When considering the movements at the ankle, plantarflexion refers to the action of pointing the toes downwards, as seen when standing on tiptoes or pressing the gas pedal in a car.

In contrast, the gastrocnemius and soleus muscles are the two main muscles involved in plantarflexion. The gastrocnemius, a large calf muscle, aids in both plantarflexion and flexion of the knee, while the soleus, located underneath the gastrocnemius, is solely responsible for plantarflexion during activities like walking or standing. The peroneus longus also contributes to plantarflexion by assisting in the movement and stabilization of the foot.

Understanding the specific functions of these muscles helps clarify their role in lower extremity movements, emphasizing the contrasting actions of the tibialis anterior with respect to plantarflexion.