Final answer:
The stretch reflex is responsible for preventing muscle overstretching and maintaining muscle tone.
Step-by-step explanation:
The reflex responsible for preventing muscle overstretching and maintaining muscle tone is the Stretch reflex. This reflex is activated when a skeletal muscle is stretched, causing a muscle spindle receptor to be activated. The axon from this receptor directly causes contraction of the muscle and also inhibits the motor neuron of the antagonist muscles, helping to maintain muscles at a constant length. A common example of the stretch reflex is the knee-move reflex that is elicited by a rubber hammer struck against the patellar ligament in a physical exam.