plantarflexion

Plantarflexion is the movement of the foot that decreases the angle between the sole and the back of the leg, effectively pointing the toes downward. Anatomically, it occurs at the talocrural (ankle) joint in the sagittal plane and is the opposite movement of dorsiflexion, which raises the foot.

The primary muscles driving plantarflexion are the triceps surae: the gastrocnemius and the soleus, transmitted to the heel via the Achilles tendon. The gastrocnemius crosses the knee and contributes more when the knee is extended, while the soleus is the dominant plantarflexor when the knee is flexed. The plantaris is a small synergist. Additional contributing muscles in the posterior compartment include flexor hallucis longus, flexor digitorum longus, and tibialis posterior, which aid in complex foot movements and push-off. The tibial nerve supplies most plantarflexors.

Normal plantarflexion range of motion is typically around 40 to 50 degrees at the ankle, though values vary with age, joint mobility, and measurement method. Dorsiflexion is usually about 0 to 20 degrees with the knee extended.

Functionally, plantarflexion is essential for standing on tiptoe, propulsion during gait, and running. Clinically, weakness or pain can indicate pathology of the calf muscles, Achilles tendon, or tibial nerve, while acute injuries may involve calf strains or Achilles tendinopathy. Assessment commonly includes resisted plantarflexion and heel-raise tests to evaluate strength and tendon integrity.