dorsiflexing

Dorsiflexion is a movement at the ankle that decreases the angle between the dorsum of the foot and the shin, bringing the top of the foot closer to the anterior leg. It mainly occurs at the talocrural joint when the foot is moved upward toward the shin, and it is opposed by plantarflexion, which points the toes downward.

Anatomy and mechanics: The primary ankle dorsiflexors are the tibialis anterior, extensor hallucis longus, and extensor digitorum longus. The peroneus tertius can assist. Nerve supply for these muscles is via the deep peroneal (deep fibular) nerve. Dorsiflexion can be influenced by knee position because the gastrocnemius, a plantarflexor, crosses the knee and can limit or permit motion depending on knee angle.

Function: In gait, dorsiflexion enables toe clearance during the swing phase and allows controlled foot placement at heel strike through eccentric contraction of the plantarflexors. It also contributes to balance when standing and helps adapt the foot to irregular surfaces.

Range of motion and testing: Normal active ankle dorsiflexion is typically about 0 to 20 degrees with the knee extended; with the knee flexed, dorsiflexion can increase somewhat (roughly 20 to 30 degrees) because the gastrocnemius is slackened. Passive dorsiflexion range varies with age, flexibility, and injury history.

Clinical relevance: Weakness of the dorsiflexors, such as from peroneal nerve injury or neurological conditions, can cause foot drop. Tight calf muscles or restricted ankle dorsiflexion can contribute to gait abnormalities and compensatory strategies. Assessment is commonly performed with goniometry and functional testing.