Final answer:
The primary function of the tibialis anterior when the heel strikes the ground during walking is concentric ankle dorsiflexion.
Step-by-step explanation:
The primary function of the tibialis anterior when the heel strikes the ground during walking is concentric ankle dorsiflexion. Dorsiflexion is the movement of lifting the front of the foot, so that the top of the foot moves toward the anterior leg. The tibialis anterior is responsible for this movement, bringing the foot closer to the shin.