l12 somatosensory Flashcards
(20 cards)
4 modalities of somatosensation
Exteroceptor
Mechanoreceptor
Thermoreceptors
Nocireceptors
Proprioceptor
Muscle + Joints
mechanoreceptor Meissnes
- Rapid
- light touch
- low frequency
close to skin
mechanoreceptor merken
slow
pressure and texture
close to skin
mechanoreceptor Pacinian
rapid
deep pressure, high frequency
deep in skin
mechanoreceptor ruffini
slow
skin stretch
sustain pressure
different classes of primary afferent
aplha: skeletal muscle proprio (biggest)
beta: touch 2nd
delta: pain and temp (rapid speed) 3rd (myelinated)
C: pain and temp (slow speed) 4th (unmyelinated)
Information pathway
Dorsal root ganglia (cell bodies of psedounipolar)-> dorsal horn
->
1. Dorsal column medial lemniscus pathway (ipsilateral, decussate at medulla)
Spinothalamic tract (bilateral)
dorsal column carry?
Proprio
Touch
spinothalamic tract carry?
pain, temp, itch
what target VPL ventral posterolateral nucleus
touch from body
what target VPS ventral posterior superior nucleus
proprio
ventral posteriormedial nucleus
touch face
touch face (go to thelamus via trigeminal thalamic tract, cell bodies in trigeminal ganglion)
.
beta
touch 2nd
.
C
p
3b + 1tactile information
- Function: fine touch + texture discrimination.
3b= directly receive primary info
1: integrate + interpret info from 3b -> perception of texture + shape - Location: postcentral gyrus, posterior to 3b.
- Location: postcentral gyrus, anterior to 1
3a proprioception
- Location: anterior of the postcentral gyrus.
Role: muscle spindles +joint receptors, inform brain about position + movement
2 direction and orientation
High Intergration of information (proprioception, tactile + muscle signal, pressure, joints) - receive input from all
* Function: processes complex aspects of touch
* Location: Located in the postcentral gyrus, posterior to area 1.
Labeled-Line Processing
specific sensory receptors + their pathways transmit specific sensory information, ensure brain accurately interprets stimuli
