Somatosensory pathways Flashcards
(37 cards)
Free nerve endings- what detects and size of receptor fields
-detects- general understanding that something is touching me (crude touch), temp, pain
-small & large
Meissner corpuscle- what detects and size of receptor fields
motion detection and grip control
small
merkel cell- what detects and size of receptor fields
shape an texture
small
(fun fact shape my finger print!)
ruffini endings- what detects and size of receptor fields
stretching of skin (they are parrallel to skin), also vibration and pressure
large
pacinian- what detects and size of receptor fields
vibration, pressire
large receptor field
diffrence between A and C fibers
A- rapid
C- slow chronic pain
How do muscle spindles detect proprioception
Being stretched “I am stretched so I must be in this position”
What are the 2 responses that muscle spindles can trigger? Explain
Muscle contraction- protective
- myotatic reflex (muscle spindle picks up on the hammer)
Antagonist inhibition- (agonist contracts too fast so antagonist tries to contract- if it cant it sends a signal to stop contraction of original agonist)
- muscle fatigue
what is the golgi tendon organ? What 2 things does it trigger?
too much tension (lifting too heavy)-> shuts off muscle (why technically you can do more than you think- protective shuts u off before you’ve reached max)
triggers: autogenic inhibition (shut down into relaxed state) or inhibits muscle spindles
Joint receptors what are they
monitor stretch in synovial joints
what are the receptors in the joints
joint receptors
pacinian (arom and compression)
ruggini (end range and prom)
free nerve endings- pain from joint inflammation, non noxious stress)
trace the general path from the distal axon to the proximal axon in the vertebrae
distal axon -> dorsal & ventral rami -> spinal nerve -> soma in dorsal root ganglion -> proximal axon aka dorsal root
what is the GENERAL pathwway of the somatosensory system from the cutaneous receptor to the postcentral gyrus
cutaneous/ muscle receptor-> PNS axon-> dorsal horn-> white motor tracts -> thalamus-> postcentral gyrus
light touch, proprioception, and vibration goes through which column
dorsal column
pain, temp, presuure, and crude touch goes through which column
anterolateral column
Medial Lemniscal Pathway path
Mechano/ proprioceptor fields->
dorsal root->
ascend via cuneatus fasciculus or gracilis fascilulus ->
synapse in caudul medulla (nucleus cuneatus or gracillis respectivly) ->
DECUSSATE (cross over) in caudul medulla and form Medial Lemniscus ->
go up to ventral posterolateral nuclus of thalamus ->
go to postcentral gyrus
What does the Medial Lemniscal Pathway convey
discrimitive touch, proprioception, and vibration
Imagine a calm monk meditating in the center (medial) of your brain, gently touching, balancing, and feeling vibrations
where is the cuneatus fasciulus and what does it impact?
UE
where is the gracilis fasciulus and what does it impact?
LE
based on when the neuron crosses over in the medial lemniscal pathway, what would a pre cross and post cross stroke look like?
cross- caudual medulla
rostral to caudal medulla: contralateral deficits
caudual to caudal medulla: same side deficits
what deos the anterolateral system convey
pain, temp, crude touch, and pressure
what is crude touch
general understanding that something is touching you
What are the 3 tracts that deal with conveying pain in the anterolateral system?
Spinoreticular- emotional and arousal aspects of pain (make sure youre alert enough to get away from the source of pain if needed) (I dont like that i got stung by a bee)
spinomesencephelic- pain modulation (brings pain down)
spinothalamic- discrimination (location, intesnsity) of pain, temp, and crude touch, pressure (I got stung by a bee!)
Explain the Spinoreticular tract of the anterolateral pathway
mechanoreceptor fields synapse immediately in the dorsal horn of the spinal cord
fibers dessate (cross) through anterior commisure and ascend in anterolateral colums to medullary pontine reticular formation in caudal pons
go to intralaminar thalamic nuclei
project farther into brain (multiple cortical projections)
