- The sense of 'Touch", is part of the Somatosensory System.
- It's made up of a number of different receptors; thermoreceptors, photoreceptors, mechanoreceptors and chemoreceptors
- But, the skin contains more than 4 million sensory receptors and is mostly concentrated in the fingers, tongue, and lips, that gather information related to touch, pressure, temperature, and pain and send it to the brain for processing and reaction.
- "Touch" is considered one of the five traditional senses, the impression of touch is formed as a part of several "modalities" including pressure, skin stretch, vibration and temperature.
- That information is sent from the receptors of the sensory nerves, through tracts in the spinal cord and then into the brain.
- The somatosensory system is spread through all major parts of a body.
- The Somatosensory path has three long neurons ; in the root of the spinal nerves, in the spinal cord or the brainstem, and in the VPN of the thalamus.
- In the periphery, the somatosensory system detects various stimuli by sensory receptors,for tactile sensation and nociceptors for pain sensation.
- In the spinal cord, the system includes ascending pathways from the body to the brain.T
- The brain is the primary somatosensory area in the human cortex that is located in the postcentral gyrus of the parietal lobe and makes up four distinct fields or regions known as Brodmann areas 3a, 3b, 1, and 2.
Fine & Crude Touch
- Fine touch is a sensory modality which allows a subject to sense and localize touch.
- Crude touch is a sensory modality which allows the subject to know that something has touched them, without being able to understand or figure out where they were touched