Referring to the sense of pressure, pain, heat, or cold in a general manner, usually without localizing the stimulus: Protopathic sensitiveness refers to the sensory nerves in the skin with a primary, grosser, or more limited sensibility to stimuli.

A protopathic sensitivity refers to the deep pain sensations and marked variations in temperature, such as hot and cold, as distinguished from "epicritic sensibility", or the sensibility to gentle stimulations permitting fine discriminations of touch and temperature as localized in the skin.

A reference to the bodily sensations of fast localized pain, slow, poorly localized pain, and temperature.

Protopathic sensibility is transmitted principally along the thinnest nerve fibers, which lack a myelin sheath and conduct nerve impulses slowly.

It is related primarily to the spinothalamic system (extending between the spinal cord and the thalamus which is the large oval area of gray matter within the brain that relays nerve impulses from the basal ganglia to the cerebellum, both parts of the brain that control and regulate muscle movement), whose receptive neuron fields are often nonspecific and very large, covering the entire body.