Somatosensory One Flashcards
Tactile (innocuous) sensations
Low threshold mechanoreceptors
Merkel, Ruffini, Meissner & Pacinian types
Proprioception
Spindle and golgi tendon receptors
Some inputs from cutaneous mechanoreceptors
Thermal sensations
Thermoreceptors localised in discrete zones that exhibit hot and cold sensitivity
Nociceptive (painful) receptors
Mechanical, thermal and polymodal nociceptors
Meissners corpuscles
Looping axonal terminals that intertwine supporting cells
Merkel’s
Dome structure atop axon terminals
Pacinian corpuscules
Sensory axon surrounded by fluid filled capsule, onion-shaped appearance
Ruffini endings
Nerve terminals intertwined with collagen fibrils
Nociceptors
Free nerve endings that penetrate epithelial cells, no morphological specialisation
Meissner corpuscles and Merkel receptor field
Merkel are the smallest.
Small receptor field
Ruffini corpuscles area on hand
Large
Pacinian corpuscles area on hand
The largest
Slow adapting cells
Merkel’s disk
Ruffini’s ending
Fast adapting cells
Meissner’s corpuscle
Pacinian corpuscle
Extract of chilli peppers
Capsaicin
Capsaicin belongs to what group of chemicals
Vanilloids
Large diameter sensory afferents
Large diameter
Rapidly conducting afferents (I/II)
Associated with low threshold mechanoreceptors
Small diameter sensory afferents
Slow conducting (III/IV) Associated with nociceptors and thermoreceptors
Primary somatosensory cortex (S1) areas
1, 2, 3a, 3b
Secondary somatosensory cortex (S2) areas
5, 7
Primary somatosensory cortex - features
Localised to post central gyrus and flanked by central and post central gyrus
Receives strong somatosensory inputs from thalamus
Each area is specialised
Secondary somatosensory cortex - features
Lies adjacent to S1 along the lateral sulcus
Plays a key role in sensory and motor integration
Receives corpus callosum inputs to form joined up body image
Build info from multiple body areas, body image
Association areas - features
Localised to posterior parietal cortex
Plays role in integration of multimodal senses
Astereoagnosia
The inability to identify objects on basis of touch alone
Neglect syndrome
Body part of visual field is disregarded
