Nerves- Sensory receptors divided into corpuscular (which contains non-nervous components) and free nerve endings; positive for S100 immunostain and contains neurofilaments
- Two main types of corpuscular endings: nonencapsulated (merkel cells) and encapsulated (Meissner’s and Pacinian corpuscles)
- Pain detected by nociceptors via either Aδ-type fibers (large) or C-type fiber
Nonencapsulated Endings- Free nerve endings : rapidly adapting receptors; majority consist of nonmyelinated C-type fibers and some myelinated Aδ-type fibers; terminal endings within epidermis and papillary dermis; mainly detects touch, pressure, and pain
- Merkel cells : found in basal layer and makes close contact with sensory nerve terminal (Merkel disc), detects touch
Encapsulated Endings- Vater-Pacini (Pacinian) corpuscle
- Rapidly adapting mechanoreceptor resembling an onion; found in deep dermis/subcutis
- Detects deep pressure and vibration; increased concentration in palms/soles, nipples, and anogenital region
- Meissner’s corpuscle
- Elongated mechanoreceptor detecting light touch (resembles pine cone); located just below DEJ (dermal papillae)and highest density in palmoplantar skin
- Ruffini corpuscle
- Thin, encapsulated, fluid-filled slow adapting receptor; found in deep dermis and detects continuous pressure
- Mucocutaneous end organs (Krause end bulbs)
- Mucocutaneous receptors found on vermilion lip, perianal region, glans penis, clitoris, and labia minora
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