Final answer:
In the somatic nervous system, only one motor neuron projects directly from the central nervous system to the effector organ, which is typically a skeletal muscle.
Step-by-step explanation:
The somatic nervous system is part of the peripheral nervous system and is involved in voluntary control of body movements through the control of skeletal muscles. Different from the autonomic nervous system which typically involves two neurons (a pre- and postganglionic neuron) between the central nervous system (CNS) and the target organ, the somatic nervous system usually employs a single motor neuron. The axon of this neuron extends from the CNS to the effector organ which is the skeletal muscle. Specifically, in the somatic nervous system, a single motor neuron projects directly from the CNS to the effector organ with its terminal ending at the neuromuscular junction where it stimulates muscle contraction.
These motor neurons, responsible for the contraction of skeletal muscles, are found in the ventral horn of the spinal cord and have relatively long axons to reach muscles in the periphery of the body. Therefore, in the somatic nervous system, only one neuron goes directly from the CNS to the effector organ, such as a muscle.