Touch

Touch

The somatosensory system is a diverse sensory system comprising the receptors and processing centres to produce the sensory modalities such as touch, temperature, proprioception (body position), and nociception (pain). The sensory receptors cover the skin and epithelia, skeletal muscles, bones and joints, internal organs, and the cardiovascular system.

While touch (also called tactile perception or tactual perception) is considered one of the five traditional senses, the impression of touch is formed from several modalities. In medicine, the colloquial term "touch" is usually replaced with "somatic senses" to better reflect the variety of mechanisms involved.

Somatic senses are sometimes referred to as somesthetic senses, with the understanding that somesthesis includes touch, proprioception and (depending on usage) also haptic perception.

The system reacts to diverse stimuli using different receptors: thermoreceptors, nociceptors, mechanoreceptors and chemoreceptors. Transmission of information from the receptors passes via sensory nerves through tracts in the spinal cord and into the brain. Processing primarily occurs in the primary somatosensory area in the parietal lobe of the cerebral cortex.

At its simplest, the system works when activity in a sensory neuron is triggered by a specific stimulus such as heat; this signal eventually passes to an area in the brain uniquely attributed to that area on the body—this allows the processed stimulus to be felt at the correct location. The point-to-point mapping of the body surfaces in the brain is called a homunculus and is essential in the creation of a body image. This brain-surface ("cortical") map is not immutable, however. Dramatic shifts can occur in response to stroke or injury.

Read more about Touch:  Anatomy, Fine Touch and Crude Touch, Physiology, Individual Differences, Diseases and Disorders, Technology, See Also

Famous quotes containing the word touch:

    My travel’s history,
    Wherein of antres vast and deserts idle,
    Rough quarries, rocks, and hills whose heads touch heaven,
    It was my hint to speak—such was my process—
    And of the cannibals that each other eat,
    The anthropophagi, and men whose heads
    Do grow beneath their shoulders.
    William Shakespeare (1564–1616)

    As a novelist, I cannot occupy myself with “characters,” or at any rate central ones, who lack panache, in one or another sense, who would be incapable of a major action or a major passion, or who have not a touch of the ambiguity, the ultimate unaccountability, the enlarging mistiness of persons “in history.” History, as more austerely I now know it, is not romantic. But I am.
    Elizabeth Bowen (1899–1973)

    The degree to which the child-rearing professionals continue to be out of touch with reality is astounding. For example, a widely read manual on breast-feeding, devotes fewer than two pages to the working mother.
    Sylvia Ann Hewitt (20th century)