Final answer:
The second neuron in an autonomic motor pathway is known as the postganglionic neuron, which connects the central nervous system to the target effector.
Step-by-step explanation:
The second neuron within an autonomic motor pathway is termed the postganglionic neuron. This neuron's axon extends from the ganglionic neuron in the autonomic nervous system and synapses with the target effector. In the autonomic nervous system, the signal is first relayed by a preganglionic neuron, which synapses with the postganglionic neuron. The autonomic nervous system is subdivided into the sympathetic and parasympathetic systems, which are responsible for the 'fight or flight' and 'rest and digest' responses, respectively.