Pavlick- Somatosensory Pathways Flashcards
Afferent information transmitted by peripheral receptors
somatosensation
where is somatosensory cortex
post-central gyrus
1st order neuron cell body is where
dorsal root ganglion
2nd order neurons found where
dorsal horn of spinal cord
what neurons will decussate
2nd order
3rd order neurons found where
thalamus (and travel to sensory cortex)
______ order neuron that conveys environmental stimulus
Cell body lies in dorsal root ganglion
first order
peripheral sensory receptor that senses vibration
pacinian corpuscle (looks like cut onion on histology)
peripheral sensory receptor that senses skin stretch
Ruffini ending
peripheral sensory receptor that senses nociception
free nerve ending
peripheral sensory receptor that senses movement across skin (slippage)
Meissner’s corpuscle
peripheral sensory receptor that senses light pressure, edges (reading brail)
Merkel disc
peripheral sensory receptor that senses tension
golgi tendon organ
peripheral sensory receptor that senses changes in muscle length and rate of length change
muscle spindle
this somatosensory pathway focuses on proprioception, vibration, and 2-point discrimination
Dorsal Column Medial Lemniscus
this somatosensory pathway focuses on, temperature, nociception, crude touch
Anterolateral system (spinothalamic)
this somatosensory pathway focuses on unconscious proprioception and balance
spinocerebellar
stimulus from tissue damage that the brain may interpret as pain
nociception
first order neuron in DCML pathway that senses discriminative touch, vibration, and proprioception
dorsal column
second motor neuron in DCML that ascend and synapse in thalamus (VPL)
medial lemniscus
3rd order neurons synapse where
synapse in primary sensory cortex (parietal lobe) and project to 4th order neurons
2nd order neurons ascend to thalamus how
ipsilaterally
above T6, first order neurons ascend and synapse where
at cuneate fasciculus of dorsal horn
below T6, first order neurons ascend and synapse where
gracile fasciculus in dorsal horn
below T6, DCML sensory info for a lot of the _______extremities
lower
_____ fasciculus deals with upper extremity sensations
cuneate
1st order neurons synapse on 2nd order neurons in
dorsal horn
decussate and ascend contralaterally as medial lemniscus and synapse on 3rd order neurons in VPL of thalamus
2nd order neurons
incomplete spinal cord injury affecting the dorsal columns
posterior cord syndrome
main causes of this include: B12 deficiency and neurosyphilis (tabes dorsalis)
posterior cord syndrome
sensory ataxia due to decreased proprioceptive input
Decreased sensation of vibration and fine touch
posterior cord syndrome
Posterior cord syndrome as a result of neurosyphilis
tabes dorsalis
Responsible for transmitting proprioceptive information (unconscious)
Spinocerebellar pathway
1st order neuron in DRG enter dorsal horn of spinal cord and synapse onto 2nd order neurons in _________ (spinocerebellar tract)
nucleus dorsalis
2nd order neurons ascend to enter cerebellum through ______ (spinocerebellar tract)
cerebellar peduncles
Responsible for transmitting nociception, temperature, and crude touch, pressure
spinothalamic tracts
1st order neurons in DRG enter dorsal horn of spinal cord, synapses with 2nd order neuron in ______ (spinothalamic tract)
substantia gelatinosa
Decussates within 1-2 levels through _______ to ascend contralaterally (spinothalamic tracts)
anterior white commissure
2nd order neurons synapse on 3rd order neurons in __________ of thalamus (spinothalamic)
VPL
3rd order neurons projects to 4th order neurons in ________ (spinothalamic)
primary sensory cortex
Fluid-filled cyst forms within central canal and compromises anterior white commissure
Syringomyelia (central cord syndrome)
“cape_” distribution of sensory loss
central cord syndrome
What is in anterior white commissure?
axons of spinothalamic tract
Lesion above motor decussation will present with motor deficits _______ to lesion
contralateral
lesion below decussation will present with deficits _________________ to lesion
ipsilateral
lesion above sensory decussation will result in deficit________ to lesion
contralateral
lesion below sensory decussation will result in deficit________ to lesion
ipsilateral
blue
red
and what location is this
DCML–blue
anterolateral system–red
spinal cord
where
caudal medulla
decussation of DCML tract
what is in the blue
“man standing on the pyramid”
medial lemniscus (2nd order neuron of DCML)
location
medulla
“walrus”
blue
pons
medial lemniscus
where
“sitting frog with mustache”
caudal midbrain
“upsidedown girl with a fro”
rostral midbrain (front of midbrain)
when 2nd order neurons (medial lemniscus) synapse where, they become 3rd order
VPL of thalamus
Midbrain structure which sends descending projections important for pain modulation
Periaqueductal Gray
Surrounding the cerebral aqueduct
important for pain modulation
Periaqueductal Gray
As afferent pain signals ascend, collateral axons synapse with PAG to activate release of pain modulating products _________
serotonin
NE
endogenous opiate peptides (internal pain killers)
where can pain be interrupted (gate theory of pain)
substantia gelatinosa of anterior white commissure
______can stimulate an interneuron to actually block pain signal from spinothalamic fibers (b/c faster signals than spinothalamic—–due to A-delta and C fibers)
DCML fibers
pressure from “Livia” attempts to do what for menstrual cramps w/ a different, faster stimulus from separate pathway (DCML)
override pain signals (block them)
f
hemisection of spinal cord
Brown-Sequard Syndrome
loss of contralateral pain/temperature
loss of ipsilateral vibration and/or proprioception below level of lesion
loss of ipsilateral motor function below level of lesion
Brown-Sequard Syndrome
