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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.

The following is a more accessble plain text extract of the PDF sample above, taken from our Neurology Notes. Due to the challenges of extracting text from PDFs, it will have odd formatting:

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



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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