Final answer:
A reflex arc is the neural pathway over which a reflex occurs, involving a sensory neuron, interneuron, and a motor neuron, with ventral horn playing a pivotal role in somatic reflexes. It provides a swift, automatic response to stimuli without direct brain involvement, thanks to the sensory pathways within the spinal cord and cranial nerves for somatosensory stimuli.
Step-by-step explanation:
The specific neural pathway over which a reflex occurs is known as a reflex arc. This pathway is a swift, automatic response to a stimulus that involves a sensory receptor, a sensory neuron, an interneuron, a motor neuron, and the corresponding effector muscle or gland. When a sensory receptor is stimulated, such as by heat or pain, it sends a signal along the sensory neuron to the spinal cord. Inside the spinal cord, the signal is transferred to an interneuron which connects to a motor neuron in the ventral horn for somatic reflexes, or the lateral horn for autonomic reflexes. The motor neuron then relays the signal to the muscle, causing it to contract and respond accordingly — all without conscious thought or direct involvement of the brain.
In terms of sensory pathways, the stimuli from various parts of the body travel through different tracts in the central nervous system (CNS). Tactile and other somatosensory stimuli from below the neck are transmitted through the spinal cord's sensory pathways, while stimuli from the head and neck pass through the cranial nerves, particularly the trigeminal system. It is the collaboration of all these pathways within the CNS that coordinates the complex processes involved in reflexes and sensory perception.