Autonomic pathways involve what arrangement of neurons?

• A. Somatic pathways require two neurons in series.
• B. Autonomic pathways involve a two-neuron chain with a peripheral ganglion.
• C. Autonomic pathways bypass the spinal cord.
• D. Somatic pathways involve a central ganglion.

Answer: (B)

Autonomic pathways use a two-neuron relay: a preganglionic neuron starts in the CNS and synapses in a peripheral autonomic ganglion onto a postganglionic neuron, which then innervates the target organ. This arrangement, with a relay point outside the CNS, allows the autonomic system to regulate smooth muscle, cardiac muscle, and glands with centralized control that can be modulated in the periphery. Somatic motor pathways, by contrast, consist of a single motor neuron from the CNS to skeletal muscle without a peripheral ganglion, so the two-neuron chain with a peripheral ganglion is the defining setup of autonomic circuits.