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Bales
Somatosensory Anatomy
55
Medical
Graduate
03/09/2011

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Term
pacinian corpuscle
Definition
Term
Dorsal column -- medial lemniscus
Definition
discriminative touch and conscious proprioception
Term
ALS (spinothalamic)
Definition
temperature, pain + crude touch
Term
cuneocerebellar, dorsal and ventral tracts
Definition
unconscious proprioception
Term
name two additional fiber systems that ascend in the ALS
Definition
spinoreticular (wakes you up when you are in pain) and spinomesencephalic fibers that travel to PAG to create feedback loop
Term
all sensory cell bodies from neck down are where
Definition
drg; central processes are 1st order axons that enter at the dorsal horn
Term
muscle spindle afferent fiber (1)
Definition
1a; heavily myelinated; fastest; largest
Term
GTO afferent fiber (1)
Definition
1b; myelinated
Term
delta fibers (3)
C fibers (4)
Definition
temperature and faster pain
temperature and slower pain
Term
touch-vibration (2)
Definition
AB II myelinated
Term
describe spatial organization of Aa (1), Ab (2), Ad (3), and C (4) fibers incoming to the dorsal horn
Definition
medial to lateral; the fibers are arranged by descending size (1,2,3,4).
Term
pseudounipolar
Definition
all DRG
Term
Abby u suck!!
Definition
Yeah well fuck you!
Term
dorsal column
Definition
conscious discriminative touch and conscious proprioception
Term
fibers are added in what direction to dorsal column
Definition
laterally; from bottom of spinal chord to top --> lower limb is added first and then trunk (medial to lower limb), etc..
Term
cuneatus fasciculus
Definition
trunk arm neck (medial to lateral); T6 ---> C6
Term
dorsal fasciculi end in what?
Definition
the nucleus gracilis and nucleus cuneatus in the caudal medulla
Term
fibers from gracilis and cuneatus nuclei in medulla decussate where?
Definition
internal arcuate fibers; medial gracillis will become more ventral and cuneatus fibers will become more dorsal
Term
describe medial lemniscus organization in rostral medulla
Definition
Limbs Trunks Arms (ventral to dorsal; man standing up)
Term
medial lemniscus shifts at medullopontine junction, describe this change in somatotopy
Definition
LTA (ventral to dorsal) to LTA (lateral to medial (man lying down)
Term
midbrain somatotopy of ML
Definition
lateral in midbrain on way to thalamus goes from ATL (medial to lateral)--> ATL ventral to dorsal (flips little man upside down)
Term
3rd order neuron in VPL travel to where?
Definition
sensory cortex in approp part of homunculus; reestablished organization of spinal cord LTA (lateral to medial)
Term
When the ML is crossing midbrain to VPL, it passes in what orientation to the red nucleus?
Definition
lateral to the red nucleus
Term
DC-ML pathway
Definition
synapse in dorsal horn laminae 1-
Term
Lesion in dorsal column or in nuclei
Definition
ipsilateral anesthesia
Term
above arcuate fibers to cortex lesions
Definition
anesthesia will be contralateral
Term
tabes dorsalis
Definition
dorsal column fibers preferentially degenerate; up to 20 years post infection; loss of dicriminative touch and loss of proprioception
Term
cord hemisection -->Brown-Sequard Syndrome
Definition
discriminative touch and conscious proprioception are lost opsilaterally from the lesion level down
Term
unconscious proprioception to cerebellum is mediated by what 4 tracts
Definition
DSCT, VSCT, CCT, RSCT
Term
CCT
Definition
Term
RSCT
Definition
DRG axon synapses in lateral dorsal horn, ipsilateral through Inferior Cerebellar Peduncle
Term
VSCT
Definition
from DRG axon synapse in spinal border cells (gray c and ventral horn) --> these decussate through ventral white column and form vsct, condense in medulla, rostral pons/midbrain level they will enter superior cerebellum peduncle and decussate back to other side of cerebellum (2 crossings)
Term
DSCT
Definition
synapse between DRG axon and cell bodies in Clarke's nucleus; C8 and up, DSCT goes through cuneocerebellar tract --> inferior cerebellar peduncle __. ipsilateral function
Term
lesions on DSCT
Definition
lack of coordination
Term
Friedrich's ataxia
Definition
dorsal column/DSCT/VSCT degeneratie, robbing patient of proprioception
Term
Brown-Sequard
Definition
masked clinically by paralysis; VSCT contralateral effect is minor
Term
Adelta
Definition
lightly myelinated
Term
C fibers
Definition
unmyelinated; pain and temperature
Term
dorsolateral tract of Lissauer
Definition
short fibered two way tract, where fibers diverge to different levels of cord
Term
Ad and C synapse in what laminae
Definition
1 and 2 (marginal zone and subgelatinosa); decussate in ventral white commisure and collect in strip called anterolateral system
Term
ALS
Definition
crude touch pain temperature
Term
lesion in ventral white commisure; e.g. syringomyelia
Definition
bilateral affect; loss of pain and temperature; syringomyelia result in cape ditribution of pain and temperature loss (explain)
Term
CT-guided electrode cordotomy
Definition
is one method of pain control; try to disrupt pain pathway
Term
describe organization of ALS
Definition
lower limb more dorsal lateral and upper limb more ventral medial
Term
where is ALS in brainstem
Definition
dorsolateral tegmentum; converges with medial lemniscus in (pons??)
Term
where does ALS synapse in diencephalon?
Definition
thalamus --> PLIC
Term
unilateral lesion in ALS
Definition
contralateral loss of pain and temperature sense at or below lesion level
Term
hemisection
Definition
ipsilateral conscious touch and proprioception and contralateral loss of pain and temperature
Term
anterior spinal arterfy infarct at T9
Definition
bilateral loss of pain and temperature around lower trunk
Term
periaqueductal gray matter
Definition
PAG --> NRM --> inhibit ALS; serotonin for NT
Term
what receptors do PAG neurons have?
Definition
opiod receptors
Term
direct inhibition of pain fibers
Definition
inhibit the 1st order pain fiber synapses in dorsal horn as downward projection from reticulospinal system.
Term
indirect inhibition of pain
Definition
NRM descending fibers stimulate interneurons that inhibit ascending pain fibers via opiod receptors
Term
Input into PAG
Definition
higher centers and spinomesenphalic tracts
Term
tabes dorsalis
May affect syphilis patients up to 20 years post infection
Definition
dorsal column fibers preferentially degenerate

May affect syphilis patients up to 20 years post infection
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