touch

The sense of touch, or mechanoreception, is the perception of direct physical contact with an object. This sense is found in organisms ranging from single-celled creatures to humans, with the entire body surface typically being receptive, except for areas protected by thick shells. Specialized structures like tactile hairs and subcutaneous receptors, including free nerve endings and corpuscles, are responsible for detecting stimuli.12

In humans, touch involves distinct spots on the skin sensitive to pressure, warmth, and cold. These spots are most concentrated on areas like the face, lips, tongue, fingertips, palms, and soles of the feet. The skin requires significant energy to detect pressure compared to hearing or sight. While some receptors respond to specific stimuli, others have a broader sensitivity, and there is considerable overlap in the areas served by individual nerve fibers. This sensory input is processed through pathways in the spinal cord and brain, allowing for the localization and discrimination of tactile stimuli.134