Final answer:
The neurotransmitter used by the somatic nervous system is acetylcholine, which is part of the cholinergic system and operates at the neuromuscular junction to activate muscles.
Step-by-step explanation:
The somatic nervous system is a part of the peripheral nervous system responsible for carrying information from the brain and spinal cord to the muscles, which enables voluntary movements. The neurotransmitter used by the somatic nervous system for this purpose is acetylcholine. Acetylcholine acts at the neuromuscular junction, meaning it is released by motor neurons to activate muscles. This neurotransmitter system is referred to as the cholinergic system, and it not only operates at the neuromuscular junction but is also distributed throughout various parts of the nervous system, including the autonomic nervous system.