The tibialis anterior is indeed the primary muscle responsible for dorsiflexion of the foot. An antagonist to the tibialis anterior is the gastrocnemius muscle.
The gastrocnemius, along with the soleus, is part of the calf muscles and is primarily responsible for plantarflexion of the foot, which is the movement that points the toes downward. While the tibialis anterior pulls the foot up towards the shin, the gastrocnemius acts in opposition by pulling the foot down when the ankle is extended. This balance between the tibialis anterior and the gastrocnemius allows for smooth movements during activities such as walking, running, and jumping.