Somatosensory system

The somatosensory system, or somatic sensory system is a subset of the sensory nervous system. The main functions of the somatosensory system are the perception of external stimuli, the perception of internal stimuli, and the regulation of body position and balance (proprioception). It is believed to act as a pathway between the different sensory modalities within the body.

As of 2024 debate continued on the underlying mechanisms, correctness and validity of the somatosensory system model, and whether it impacts emotions in the body.

The somatosensory system has been thought of as having two subdivisions;

The sense of touch in perceiving the environment uses special sensory receptors in the skin called cutaneous receptors. They include mechanoreceptors such as tactile corpuscles that relay information about pressure and vibration; nociceptors, and thermoreceptors for temperature perception.

Stimulation of the receptors activate peripheral sensory neurons that convey signals to the spinal cord that may drive a responsive reflex, and may also be conveyed to the brain for conscious perception. Somatosensory information from the face and head enter the brain via cranial nerves such as the trigeminal nerve.

The neural pathways that go to the brain are structured such that information about the location of the physical stimulus is preserved. In this way, neighboring neurons in the somatosensory cortex represent nearby locations on the skin or in the body, creating a map or sensory homunculus.

Tactile signing is a common means of communication used by people with deafblindness. It is based on a sign language or another system of manual communication.

Humans can communicate specific emotions through touch alone including anger, fear, disgust, love, gratitude, and sympathy via touch at much-better-than-chance levels.