Final answer:
Lower motor neurons are the somatic motor neurons that innervate skeletal muscles, primarily located in the ventral horn of the spinal cord. Their long axons travel through nerves to reach and stimulate the muscles. These neurons control muscle contraction and vary in the number of muscle fibers they innervate based on the muscle's function.
Step-by-step explanation:
The lower motor neurons are somatic motor neurons with cell bodies in the brain stem or spinal cord and axons that travel within the nerves to stimulate skeletal muscles.
The somatic nervous system provides output strictly to skeletal muscles. The lower motor neurons responsible for the contraction of these muscles are found in the ventral horn of the spinal cord. These large, multipolar neurons have a corona of dendrites surrounding the cell body, and an axon that extends out of the ventral horn through the ventral nerve root, eventually joining the emerging spinal nerve. The long axons are essential as they need to reach muscles throughout the body, with some being up to a meter in length like the lumbar motor neurons that innervate muscles in the first digits of the feet.
These motor neurons originate in the spinal cord and also in the brainstem for skeletal muscles of the face, head, and neck. The axons bundle together to form nerves, which connect to the muscles at neuromuscular junctions. A single motor neuron may innervate multiple muscle fibers, with the number of fibers depending on the required precision and force for that motor unit.