Somatosensory Physiology Notes

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This is an extract of our Somatosensory Physiology document, which we sell as part of our Neurology Notes collection written by the top tier of Bristol University students.

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Lecture 11 Somatosensory Physiology- Peripheral terminations of non nociceptive DRG neurons

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Somatosensory nervous system o Transmits all sensory (or afferent) neural info, excluding the special senses o Includes nerves sending info from
? Skin; Sensors in muscles and tendons; Sensors in visceral organs and tissues Non-nocicpetive cutaneous afferent fibre types o Glaborous skin
? Pacinian corpuscle

* Non hairy and hairy skin

* 1mm in length

* Fingers, toes, genitals

* 20-60 concentric lamellae of fibrous connective tissue/fibroblasts

* The lamellae are very thin, flat, modified Schwann cells

* Fluid-filled cavity with a single afferent unmyelinated nerve ending

* Detect tap and (particularly) vibration

* Very rapidly adapting low threshold mechanosensitive Abeta fibres
? Meissner's corpuscle

* Responsible for "light touch" and low frequency vibration

* Just below epidermis

* Rapidly adapting low threshold mechanoreceptor, Abeta fibres

* Not in hairy skin

* Unmyelinated endings enclosed in capsule

* Corpuscle=30-140micrometres length; 40-60micrometers diameter Composed of elastin attached to epidermis
? Merkel's cells

* Oval receptor ~10micrometres cells in skin and oral/rectal mucosa and mammary glands

* Synaptic contact with disc like terminal of SA1 low threshold mechanosensitive AB fibres (branch innervating up to 90 cells)

* Stratum basale of epidermis clustered in touch domes

* Light touch (Braille)

* Small receptive field

* Transmitter may be glutamate
? Ruffini end organ

* Slowly adapting mechanoreceptors in deep sites skin (hairy, glabous) & also in joints

* Monitor tissue stretch

* May also sense heat

* Innervated by single Abeta fibres which branch in corpuscle ending
? End-bulbs of Krause

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