Somatic senses Flashcards
Four encapsulated receptors of non-hairy skin and their classification
Meissner corpuscle (RA1), Merkel cells (SA1), Pacinian corpuscle (RA2), Ruffini Corpuscle (SA2)
merkel receptors are sensitive to? useful for?
very fine touch, esp edges. Stereognosis
meissner receptors are sensitive to? useful for?
vibration, stroking. grip adjustment for slipping object
ruffini corpuscle are sensitive to
pressure or stretch of skin
pacinian corpuscle are sensitive to
small amplitude vibrations (tuning fork). Much more sensitive than meissner’s
what determine’s a receptor’s adaptation and receptive field size?
capsules (make axons rapidly adapting) and depth (deeper= broader field)
what two factors determine two point threshold
receptor depth and density
can merkel cells encode pain and sharpness.
sharpness (shape) but not pain
what fibers encode pain and temp
A delta and C fibers. Small and unencapsulated
muscle spindle 1a fibers: important in? parallel or series? responsive to? Large or small fibers
tendon tap monosynaptic reflex. parallel. Stretch (length as well as changes in length). Large fibers
what synapses in the nuclei gracilis and cuneatus
gracilis- trunk, legs. Cuneatus- neck, shoulder, arms
medial medullary syndrome will affect___. Lateral medullary syndrome will affect___.
medial lemniscus. Spinothalamic tract
path of dorsal column/medial lemniscus
first order enters cord, travels up dorsal column, synapses at gracile/cuneate nuclei, second order decussates, medial lemniscu to VPL/VPM. Third order to postcentral gyrs
Path of spinothalamic (anterolateral) tract
first order synapses in dorsal horn of cord, second order decussates immediately and up anterolateral tract to thalamus, third order to postcentral gyrus
BRown Sequard syndrome
tumor compresses one side of cord. Ipsilateral loss of tactile and position in legs, contralateral loss of pain and temp
