Tactile corpuscle

Tactile corpuscle
Papilla of the hand, treated with acetic acid. Magnified 350 times. Side view of a papilla of the hand. Cortical layer. Tactile corpuscle. Small nerve of the papilla, with neurolemma. Its two nervous fibers running with spiral coils around the tactile corpuscle. Apparent termination of one of these fibers. A tactile papilla seen from above so as to show its transverse section. Cortical layer. Nerve fiber. Outer layer of the tactile body, with nuclei. Clear interior substance.
Details
Latin	corpusculum tactus
Identifiers
MeSH	A08.800.550.700.500
Code	TH H3.11.06.0.00007
Dorlands /Elsevier	12261393
TA
TH	{{#property:P1694}}
TE	{{#property:P1693}}
FMA	{{#property:P1402}}
Anatomical terminology [[[d:|edit on Wikidata]]]

Tactile corpuscles (or Meissner's corpuscles) are a type of mechanoreceptor. They are a type of nerve ending in the skin that is responsible for sensitivity to light touch. In particular, they have highest sensitivity (lowest threshold) when sensing vibrations between 10 and 50 Hertz. They are rapidly adaptive receptors. They are most concentrated in thick hairless skin, especially at the finger pads.

Location

They are distributed on various areas of the skin, but concentrated in areas especially sensitive to light touch, such as the fingers and lips. More specifically, they are primarily located in glabrous skin just beneath the epidermis within the dermal papillae.

Structure

Tactile corpuscles are encapsulated unmyelinated nerve endings, which consist of flattened supportive cells arranged as horizontal lamellae surrounded by a connective tissue capsule. The corpuscle is between 30-140 μm in length and 40-60 μm in diameter.

A single nerve fiber meanders between the lamellae and throughout the corpuscle.

Age-related changes

The number of tactile corpuscles per square millimeter of human skin on the fingertips drops fourfold between the ages of 12 and 50. The rate at which they are lost correlates well with the age-related loss in touch sensitivity for small probes (Thornbury and Mistretta, 1981).

Function

Tactile corpuscles are rapidly adapting mechanoreceptors. They are sensitive to shape and textural changes in exploratory and discriminatory touch. Their acute sensitivity provides the neural basis for reading Braille text. Because of their superficial location in the dermis, these corpuscles are particularly sensitive to touch and vibrations, but for the same reasons, they are limited in their detection because they can only signal that something is touching the skin.

Any physical deformation in the corpuscle will cause an action potential in the nerve. Since they are rapidly adapting or phasic, the action potentials generated quickly decrease and eventually cease (this is the reason one stops "feeling" one's clothes).

If the stimulus is removed, the corpuscle regains its shape and while doing so (i.e.: while physically reforming) causes another volley of action potentials to be generated.

Comparison with other receptors

Feelings of deep pressure (from a poke, for instance) are generated from lamellar corpuscles (the only other type of phasic tactile mechanoreceptor), which are located deeper in the dermis, and some free nerve endings.

Also, tactile corpuscles do not detect pain; this is signalled exclusively by free nerve endings.

Eponym

Meissner's corpuscles were discovered by the anatomist Georg Meissner (1829–1905).

Additional images

• 

  "Meissner's corpuscle" labeled at upper right

• 

  Diagrammatic sectional view of the skin.

• 

  light micrograph

External links

• Donald L. Rubbelke D.A. Tissues of the Human Body: An Introduction. McGraw-Hill. 1999 Meissner's and Pacinian corpuscles
• Dawn A. Tamarkin, Ph.D. Anatomy and Physiology Unit 15 Vision and Somatic Senses: Touch and Pressure
• Histology image: 08105loa – Histology Learning System at Boston University - "Integument pigmented skin, Meissner's corpuscles "
• Anatomy Atlases - Microscopic Anatomy, plate 06.123 - "Meissner's Tactile Corpuscle"
• Histology at rutgers.edu