Mechanoreceptors

Thalamic Nuclei for Mechanoreceptor information

Ventral posterolateral nuclei

Slow adapting

tonic - fire continuously, for constantly present stimuli

Fast adapting

phasic - fire rapidly initially, for changes in stimulu

Glabrous skin

hairless skin, palms of hands and bottom of feet

Hairy skin

majority of skin

mechanoreceptors in glabrous skin

mainly meissner’s corpuscles

mechanoreceptors in hairy skin

fewer touch receptors

Meissner’s Corpuscles Location

Below epidermis of glabrous skin, in the dermal papillae of papillary dermis

Meissner’s Corpuscles Detection

discriminative fine touch and low-frequency vibrations

Meissner’s Corpuscles Structure

like sperm - unmyelinated axons surround stacks of lamellar cells, endoneurial capsule surrounds, and axon becomes myelinated

Meissner’s Corpuscles Speed

Fast adapting type I

Mechanoreceptor transduction

physical deformation acts as stimulus, generates AP, into dorsal root then dorsal column and up to S1

Ruffini Endings Location

dermis of glabrous and hairy skin, parallel to stretch lines

Ruffini Endings Structure

unmyelinated tree branches of an axon embedded in glial cells, surrounded by endoneurial capsule

Ruffini Endings Speed

Slow Adapting Type II

Ruffini Endings Detection

stretching of skin, small proprioceptive angle changes, continuous pressure, thermoreceptor (heat)

Pacinian Corpuscles Location

deep dermis and hypodermis of glabrous and hairy skin, viscera and joints

Pacinian Corpuscles Detection

vibration(high) and pressure of grasp and release

Pacinian Corpuscles Structure

Neural compartment with unmyelinated axon and lamellar cells, intermediate layer of fibrous capsule, non-neural component containing and outer core and capsule

Pacinian Corpuscles Structural Distinction

uniform distribution

Pacinian Corpuscles Speed

Fast Adapting Type II

Merkel’s Cells Location

In epidermis but along dermal ridges of glabrous and hairy skin

Merkel’s Cells Structure

cell embedded in dermis with a disk below it, completely myelinated

Merkel’s Cells Speed

Slow Adapting Type I

Merkel’s Cells Detection

light pressure, proprioception, deep static/continuous touch

Merkel’s Cells Transduction

deformation of cell, release NT received by disk to create AP

Minor Mechanoreceptors

Hair and Nerve fibers, free nerve endings