Touch is one of the traditional five senses, along with hearing, sight, smell, and taste. Touch is one of the first senses developed and occurs across the whole body. A network of neural structures in the brain and body produces the sense of touch. It is activated when internal organs sense physical stimuli such as pressure on or contact with the skin. These signals are combined with feedback from muscles and tendons as we actively move and explore the world around us. Touch can produce a positive or negative reaction depending on the type of touching. The types of touch are many. It can be a soothing touch, a healing massage, an affectionate hug or embrace, a brush from a spider web, a mosquito bite, a violent punch, a burn, or a cut.
Skin, the body’s largest organ, is the main organ involved in the sense of touch. It consists of three main layers of tissue: The outer epidermis, middle epidermis, and inner hypodermis.
Receptor Cells
Within these three layers are specialized receptor cells that detect tactile sensations and relay signals through peripheral nerves toward the brain.
There are four mechanoreceptors in the skin that each respond to different stimuli for short or long periods. Each of the different types of receptors makes certain body parts more sensitive.
Merkel cells are in the lower/basal epidermis of lips, hands, fingertips, external genitalia, and hair follicles. They react to low vibrations (5-15 Hz)
Tactile corpuscles or Meissner corpuscles are in the upper dermal papillae of hairless skin, primarily in the fingertips, lips, nipples, and soles of feet. Both of these receptors detect touch, pressure, and vibration. They react to moderate vibration (10-50 Hz) and light touch. Unlike Merkel’s nerve endings, they respond in quick action potentials. They are responsible for the ability to read Braille and feel gentle stimuli.