Final answer:
The gastrocnemius muscle inserts on the calcaneus through the Achilles tendon and is vital for upright locomotion and various leg movements.
Step-by-step explanation:
The muscle that inserts on the calcaneus is the gastrocnemius. This muscle, alongside thesaurus and plantaris, attaches to the calcaneus bone via the Achilles tendon. The gastrocnemius is the most superficial and visible muscle in the calf and forms part of the superficial posterior compartment of the leg, which plays a crucial role in keeping humans upright and performing movements such as walking, running, and jumping.