Question

The brain orders muscles to contract is called ______.​

Answer 1

Answer:

motor neurons

Explanation:

Muscles move on commands from the brain. Single nerve cells in the spinal cord, called motor neurons, are the only way the brain connects to muscles. When a motor neuron inside the spinal cord fires, an impulse goes out from it to the muscles on a long, very thin extension of that single cell called an axon.

Answer 2

An easier Brief explanation
If the question demand in depth answer talk about motor neurons
In order to contract, voluntary muscles must be stimulated by the somatic nervous system. ... When the brain decides to move part of the body and gives the command to the motor neurons to execute this movement, it is the muscles at the end of the chain of command that ultimately contract to move the body part concerned.