Final answer:
The muscles in the anterior compartment of the leg, including the tibialis anterior, extensor hallucis longus, and extensor digitorum longus, are the primary antagonists to the muscles that insert on the calcaneus via the calcaneal tendon.
Step-by-step explanation:
The primary antagonist of the muscles that insert on the calcaneus (the heel bone) are the muscles located in the anterior compartment of the leg. These muscles are responsible for dorsiflexion of the foot, which is the opposite movement to plantar flexion that is carried out by the muscles inserting on the calcaneal tendon (also known as the Achilles tendon). The calcaneal tendon is a strong tendon that attaches the gastrocnemius, soleus, and plantaris muscles of the posterior compartment of the leg to the calcaneus bone. The antagonist muscles include the tibialis anterior, extensor hallucis longus, and extensor digitorum longus, which are involved in lifting the front of the foot or dorsiflexion, countering the action of the plantar flexors.