Somatosensory

Somatosensory system is a complex system of sensory neurons and neural pathways that responds to changes at the surface or inside the body. The axons (as afferent nerve fibers), of sensory neurons connect with, or respond to, various receptor cells. These sensory receptor cells are activated by different stimuli such as heat and nociception, giving a functional name to the responding sensory neuron, such as a thermoreceptor which carries information about temperature changes. Other types include mechanoreceptors, chemoreceptors, and nociceptors which send signals along a sensory nerve to the spinal cord where they may be processed by other sensory neurons and then relayed to the brain for further processing. Sensory receptors are found all over the body including the skin, epithelial tissues, muscles, bones and joints, internal organs, and the cardiovascular system.

Structure

Somatosensory system is divided into the peripheral and central system. The peripheral system includes the nerves and ganglia outside of the brain and spinal cord. The central system is the part of the nervous system that is enclosed in the meninges.

Peripheral system

The peripheral somatosensory system is the first stage of the bodily processing of somatic sensation. It is composed of sensory receptors, or nerve endings, that respond to various kinds of stimuli. These sensory receptors are either free nerve endings or structures specialized for specific types of sensation such as touch, temperature, body position, and pain. The sensory information from these receptors is transmitted to the brain by afferent neurons, which make up the peripheral nerves.

Central system

The central somatosensory system is the part of the somatosensory system that processes and interprets information from the peripheral system. It includes the spinal cord and brain. The primary somatosensory area in the human cortex is located in the postcentral gyrus, and makes up four distinct fields or regions known as Brodmann areas 3, 1, and 2, and the secondary somatosensory cortex.

Function

The somatosensory system is responsible for processing sensory information from the skin and internal organs. It also plays a key role in proprioception, or the sense of relative position of neighboring parts of the body and strength of effort being employed in movement.

Clinical significance

Damage to the somatosensory system can result in a variety of neurological conditions, such as somatosensory loss, pain syndromes, and somatosensory disorders. Treatment for these conditions can involve medication, physical therapy, or surgery.

See also

• Nervous system
• Sensory system
• Proprioception
• Pain

Somatosensory Resources
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