Mechanoreceptors

Things to know…

What are they? Somatosensory cells that respond to various physical stimuli or sensations

Neural crest cell origination (debated): TFs MafA and c-Maf help induce differentiation

Mechanoreceptor	Encapsulation¹	Receptive field and frequency²	Depth in integument	Location	Type of touch	Fibers	Other
Free nerve endings	No	Typically SA	Throughout epidermis and dermis, especially in deeper epidermis and papillary dermal layers	Widespread throughout body	Nociception, temperature, coarse touch, itching	C fibers (unmyelinated if for pain/warmth) or Alpha-delta fibers (sharp pain/cold)	Thin axons and highly branched, little structural differentiation
Krause end bulbs	Yes	Low-threshold SA	Deep dermis or subcutaneous tissue	Penile and clitoris skin	Low frequency vibrations, light touch, cold	Alpha-beta	Ovoid; thin collagenous capsules
Merkel/tactile discs	No	SA1	Basal epidermis	Fingertips, lips (high sensitivity areas), hands	Light touch	Alpha-beta (single, myelinated afferent)	Expanded nerve endings, joined to keratinocytes via desmosomes
Meissner/tactile corpuscles	Yes	RA1	Dermal papillae	Especially prominent on hairless areas of fingertips, palms, soles, and also eyelids, external genitalia	Low frequency vibrations, light touch	Alpha-beta	Elliptical axons with schwann cells; numbers decline after puberty; two point discrimination test
Ruffini endings	Yes	SA2	Dermis	All skin, joint capsules, ligaments/tendons	Skin stretch/torque, prolonged pressure, joint movement	Alpha-beta	Collagenous fusiform capsules anchored to CT; dendrites intertwined with collagen network
Pacinian/lamellated corpuscles	Yes	RA2	Deep dermis or subcutaneous tissue	Fingers, joints, interosseous membranes (detect skeletal muscle vibration), mammary glands, genitalia, organ CT (e.g., rectal wall, urinary bladder)	Deep pressure, high frequency vibrations, coarse and sustained touch	Alpha-beta	Large and ovoid; has thin concentric lamellae and highly branched unmyelinated axon with single dendrite

¹Encapsulation refers to the presence of connective tissue (CT) structures and supportive Schwann cells (non-myelinating). ²Mechanoreceptors are categorized by the size of its receptive field (RF) and the type of frequency it responds to: RA1 (smaller RF, low frequency vibration), RA2 (large RF, high frequency), SA1 (small RF, continual static frequency), SA2 (large RF, continuous static)

Updated: 7/26/25