CM: Intro to CNS Flashcards
Where do cerebellar lesions cause deficits?
ipsilateral
What is the pathway of the corticospinal tracts?
origin = cortical motor neurons
descend through internal capsules and medullary pyramids
most cross in lower medulla and continue as lateral corticospinal, some remain uncrossed and become anterior (ventral) corticospinals
What is the pathway of the medial lemniscus system?
fine touch, vibration, proprioception origin = dorsal root ganglia ascend ipsilaterally in gracile and cuneate fasciculi, synapses in nuclei cross in lower medulla synapses in VPL contralateral to origin
What is the pathway of the spinothalamic tracts?
pain and temp
origin = dorsal root ganglia
crosses at level of cord after synapsing in dorsal horn
synapses in VPL contralateral to origin
What is hemi-cord (Brown-Sequard) syndrome?
loss of fine touch and proprioception ipsilateral
loss of pain and temp contralateral
if above gracile and cuneate nuclei - both contralateral
What do lesions at these places cause in vision?
a. eye or optic nerve
b. optic chiasm
c. optic tract or lateral geniculate
d. inferior optic radiation (temporal lobe)
e. superior optic radiation (parietal lobe)
f. medial occipital cortex/white matter
a. monocular blindness ipsilateral
b. bilateral hemianopsia
c. contralateral homonymous hemianopsia (if right side, loss of left half of both eyes)
d. contralateral superior quadrantanopsia = pie in the sky
e. contralateral inferior quadrantanopsia
f. optic tract except macular sparing
What is the direct loop of the basal ganglia?
releases thalamus from inhibitory signals from basal ganglia –> increased motor activity
indirect loop does the opposite
Where is localization of a lesion easier?
peripheral - signs and symptoms restricted and don’t change much over time unlike central
What sensory disturbances can a lesion in the brain cause?
sensory loss with or without weakness (pure)
sensory loss can be entire side including face
lesion in brainstem may cause ipsilateral facial numbness w contralateral body but usually other CN signs
What sensory disturbances can a lesion in the spinal cord cause?
loss of subset of various sensory modalities
no facial involvement
What is anterior spinal artery syndrome?
hits front 2/3 of cord
loss of pain and temp with preservation of vibration and proprioception (dorsal columns okay)
What is tabes dorsalis?
manifestation of tertiary syphilis - just dorsal columns affected - lose vibration and proprioception
What is poliomyelitis?
anterior horn cells knocked out - weakness of muscles and atrophy, decreased DTRs
What is subacute combined degeneration?
severe B12 def –> both dorsal columns and corticospinal tracts impaired
What are Wernickes and Broca’s areas responsible for?
Wernicke’s - phonological recognition = decoding language
Broca’s - phonological production
