Neuro Exam 3.2
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Neuro Exam 3.2
neuroscience neurology neuroanatomy
review of lecture 2 for neuro exam 3
Does lesion in a pathway cause an ipsolateral or contralateral effect?
The reference point is always the lesion
Which types of neurons are damaged and where are they located in the spinal cord?
What modalities would be lost?
Where would the loss of modalities occur?
Where does decussation occur?
Where do 1st order sensory neurons originate?
Where do 2nd order sensory neurons originate?
Where do 3rd order sensory neurons originate?
Which neurons pass through the internal capsule?
Understand that all sensory info must be processed by the thalamus (except smell)...
before you can consciously perceive it
All sensory info can be responded to reflexively at the spinal cord or the brain stem level w/o being:
What is the pathway of information?
external energy-->receptors on distal ends of sensory neurons-->action potentials-->afferent sensory neurons of PNS
What are the types of external energy?
What happens at the receptors on distal ends of sensory neurons?
transduction of energy
What type of process are action potentials?
What are some examples of afferent sensory neurons of the PNS?
cranial and spinal nerves
For the purpose of sensory pathways, what is considered general sensation?
How many general sensations apply to somatic receptive fields?
How many general sensations apply to visceral receptive fields?
most except for two-point discrimination, stereognosis, conscious proprioception
What is the spinothalamic tract responsible for?
noxious stimulation, pain, temperature, crude touch
Where does the spinothalamic tract receive input from?
UE, LE, trunk, abdomen, and pelvis
As the spinothalamic tract ascends the spinal cord, it adds more and more:
2nd order sensory neurons
Is the spinothalamic tract larger at the bottom or the top?
Where are 1st order neurons of the spinothalamic tract located?
in spinal nn or nerves of ANS
What type of receptive fields are found in the 1st order neurons of the spinothalamic tract?
somatic and visceral
What are found in the 1st order neurons of the spinothalamic tract?
cell bodies in DRG of spinal nerves
What do 1st order neurons of the spinothalamic tract synapse with?
2nd order in dorsal horn; may or may not synapse w/ interneurons
Where do 2nd order neurons of the spinothalamic tract decussate?
immediately at point of entry to contralateral side and ascend as spinothalamic tract
What do the 2nd order neurons of the spinothalamic tract become?
When do the 2nd order neurons of the spinothalamic tract become the spinal lemniscus?
upon entry to the tegmentum of the brainstem
After the spinal lemniscus continues through the tegmentum it terminates w/:
thalamus at ventral posterior lateral nucleus (VPL=R nucleus)
Where do 3rd order neurons of the spinothalamic tract synapse?
b/w 2nd and 3rd order in thalamus
Where do 3rd order neurons of spinothalamic tract ascend?
through internal capsule to terminate in postcentral gyrus of parietal lobe
What modalities are lost if spinothalamic tract is cut?
lose perception (pain, temp, crude touch) of contralateral side below level of lesion, if tract is cut once it enters spinal cord
lose perception of ipsilateral side if tract is cut at a spinal nerve
It is called the spinothalamic tract of the left side of the spinal cord
NOT the left spinothalamic tract!!
What is the dorsal column system responsible for?
Where are 1st order sensory neurons found?
Where are the cell bodies of the 1st order neurons of the dorsal column system?
dorsal root ganglion (DRG)
Where are the receptors of the dorsal column system found?
What structure does the 1st order neurons of the dorsal column system enter?
Do the 1st order neurons of the dorsal column system decussate?
Where does the 1st order neuron of the dorsal column system ascend?
ipsilaterally in dorsal white column to medulla
1st order from LE that synapses w/ nucleus gracilis in tegmentum of the medulla (medial)
1st order from UE that synapses w/ nucleus cuneatus in tegmentum of the medulla (lateral)
Where do the 2nd order neurons of dorsal column system decussate?
When the 2nd order neuron of the dorsal column system decussates in the medulla it collectively forms what?
Where does the 2nd order neurons of the dorsal column system ascend?
to tegmentum of brainstem
Where does the 2nd order neurons of the dorsal column system terminate?
ventrobasal nucleuar complex of thalamus
What do 2nd order neurons of the dorsal column system synapse with?
3rd order neurons in thalamus
What structure does the 3rd order neuron of the dorsal column system pass through?
After passing through the internal capsule where does the 3rd order neuron of the dorsal column system go?
to postcentral gyrus of parietal lobe
What does the 3rd order neuron of dorsal column system do once in the postcentral gyrus of parietal lobe?
What modalities are lost if the dorsal column system is cut?
loss on ipsilateral side if cut at or before the medulla (dorsal column of SC)
loss on contralateral side if cut after the medulla (ex
: if lesion is in pons)
What is the spinocerebellar tract responsible for?
Where are the 1st order neurons of the spinocerebellar tract located?
Where are the cell bodies of the 1st order neurons of the spinocerebellar tract?
Where are the receptors of the 1st order neurons of the spinocerebellar tract?
Where do the 1st order neurons of the spinocerebellar tract terminate?
dorsal horn (specifically lamina VII --aka Nucleus dorsalis or Clarke's nucleus) to synapse w/ 2nd order
What are the 2nd order neurons of spinocerebellar tract associated w/?
What two tracts are there with the 2nd order neurons of spinocerebellar tract?
anterior and posterior
Does the posterior spinocerebellar tract decussate?
The posterior spinocerebellar tract enters what?
cerebellum via inferior cerebellar peduncle
Why does the posterior spinocerebellar tract enter the cerebellum?
to relay info from LE
Does the anterior spinocerebellar tract decussate?
yes, at point of entry
The anterior spinocerebellar tract enters what?
cerebellum via superior cerebellar peduncle (superior is primarily efferent--though anterior spinocerebellar tract is an exception to this rule)
Lesions of the 2nd order neurons of the spinocerebellar tract result in:
loss of motor control (but this is more finesse type so less noticeable clinical symptoms)