What is the nerve pathway involved in a reflex action including a sensory nerve and a motor nerve with a synapse between?

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A reflex arc is the nerve pathway that mediates reflex actions. It describes the circuit where a sensory receptor sends signals through a sensory (afferent) neuron to the spinal cord or brainstem, where a synapse transfers the signal to a motor neuron (often via an interneuron), and the motor neuron then drives the effector muscle or gland. The scenario described—having a sensory nerve and a motor nerve with a synapse between them—fits this pathway exactly, enabling a rapid, automatic response without deliberate thought. For example, the knee-jerk reflex involves a direct synapse in the spinal cord between the sensory neuron and motor neuron, producing a quick leg kick. The other terms refer to parts or aspects of the circuit (afferent pathway is only the sensory route, efferent pathway is only the motor route, synapse is just the junction) rather than the full reflex action pathway.