Lecture 2-spinal cord Flashcards by Audrey Chu

what are the boundaries of the spinal cord?

top/rostral/superior:

foramen magnum
1mm caudal to the pyramidal decussation

bottom/caudal/inf
-btwn L1 and L2 vertebrae
site of conus medullaris

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what do the cervical enlargements innervate?

what about the lumbar enlargement?

upper extremities

lower extremities

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which space is CSF in

subarachnoid space

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what are the differences btwn cranial and spinal meninges?

dura in the cord has only 1 layer. in the brain there are 2
- outer dural layer that is present i nthe brain end at the foramen magnum, so the cord only covered by an inner investing dural layer
epidural space is not a potential space in cord but an actual space filled w/ fat and veins

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what do the meninges of the brain and cord have in common

shared subarachnoid space bc CSF is able to bathe the cord and spinal nerve roots

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CSF heads caudally to the

lumbar cistern

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how is the spinal cord pairs divided up

8 cervical 
12 thoracic 
5 lumbar 
5 scaral 
1 coccygeal

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what does each spinal nerve innervate?

what does each spinal cord segment innervate?

a single dermatome and myotome

a dermatome and a myotome

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what does the cervical enlargemnt innervate

upper extremities from C5 to T1

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what does the lumbosacral enlargement innervate

lower extremities from L2 to S3

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where does the spinal cord end

btwn L1 and L2 vertebrae

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what is a papilledema

the bilateral sweling of both optic discs due to increased intracranial pressure

if the pt develops a space occupying lesion (tumor or bleeding) there’s not enough room in skull so the ICP increases and can be transmistted along both optic nerves due to the SHARED SUBARACHNOID SPACE.
same CSF that circulates around the brain and cord so its also around the optic nerces

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what are the two investigations needed for possible causes of elevated ICP

neuroimaging (MRI/MRV) to look for structural lesions
if imaging is normal, next is CSF analysis by lumbar puncture

if LP proves that the ICP is high, then the bilarteral disc edema can be specifically called a papilledema

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where is CSF sampled from in a LP

lumbar cistern

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what does a LP allow documentation of?

the CSF sample is sent to a lab to analyze its…?

opening pressure

2. composition

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where is the lumbar cistern located

just below the spinal cord itself but still within the dural sac (from L1-L2 vert to S2 vert)

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where is the needed in an LP for adults placed?

L3-L4 or L4-L5

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what is the preferred pt position when doing an LP?

lateral decubitus

lying on side
in fetal position

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what is the cut-off of the normal range of the opening pressure?

> 250 mmH2O

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where does the dural sac end

S2 (therefore thats where the lumbar cistern ends also)

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where is the conus medullaris

what is it

just below L1

caudal termination of the cord

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where is the cauda eqina

spinal nerve roots from the lumbosacral region extending beyond the conus medullaris

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what is the filum terminale

a thickening of the meninges which anchors the spinal cord around the coccyx

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are spinal nerves CNS?

no, they are PNS

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what are spinal nerves covered by | spinal roots?

epineurium | meningies

what are dorsal roots

afferent sensory fibers entering the cord.

what type of neurons are dorsal root ganglion

pseudo-unipolar neurons w/ both central and peripheral processes

what are ventral roots | where are their cell bodies or origin

- efferent motor fibers going out to the periphery. probaby to innervate somatic or autonomic muscles - inside the spinal cord's gray matter

each spinal nerve if formed by the union of what? | what kind of fibers do they contain?

dorsal and ventral root | sensory and motor fibers (mixed nerve(

what are the roots and rootlets enclosed in ? | what is the spinal nerve ?

1. dural sleeve | 2. epineurium

waht do the spinal nerve branch off into? what kind of fibers do they contain?

dorsal and ventral rami | motor and sensory fibers, mixed

ventral/anterior rami become what because they are so big? between what do they not form those? and why?

plexi T2 and T12 sympathetics

what does the smaller dorsal primary ramus innervate?

-skin of back, -deep back muscles, - joints btwn vertebrae both sensory and motor

what do the ventral rami supply?

skin of trunk and limbs | muscles of trunk and limbs

Primary rami are.... spinal nerves are...... dorsal roots are.... ventral roots are....

mixed mixed sensory motor

white rami communicans are only present where.... gray rami? why?

- T1-L3 bc sympathetic preganglionics are only present thoracolumbar - present at all levelts bc all levls of the body get post gagnlionic sympathetic fibers

how many pairs of cranial nerves are there? where do they exit from? how many pairs of spinal nerves are there? where do they exit from/

12 pairs, exit through skull foramina | 31 pairs, exit through intervertebral foramina

do peripheral nerves contain sensory or motor info?

it depends-bc spinal nerves are mixed but cranial nerves can be mixed, sensory, or motor.

what are the targets of the ANS | how do they innervate their targets

cardiac muscle, smooth muscle, and glands | through a 2 neuron chain

what are the two neurons in the 2 neuron chain

1: pre-ganglionic neuron, originiates inside the CNS , which means the cell bodies of origin are from the brain or spinal cord 2: postganglionic neuron, originates in the ganglion which means cell bodies of origin are in the PNS

if the preganglionic cell body is craniosacral (in brainstem or sacral spinal cord), it is... if the preganglonic cell body is thoracolumbar (located in the thoracic or lumbar spinal cord) it is..

parasympathetic , its axons will exit the brainstem as cranial nerves or ventral roots and then spinal nerves sympathetic, its axons exit via ventral roots

what does cranio mean? what does sacral mean?

preganglionic cell bodies are located in cranial nerve nuclei in the brainstem CN nuclei 3, 7, 9, 10 preganglionic cell bodies are located in the sacral region of the spinal cord and are S2 to S4

what does it mean to say "thoracolumbar"

sympathetic pre ganglionic cell bodies that are located in teh T1-L3 spinal cord segments in the lateral horn gray segments of T1-L3

lateral horns contain ....

ANS motor info, specifically sympathetic preganglionic efferents

which cranial nerves are parasympathetic in function? sympathetic?

3, 7, 9, 10 | NONE

what are the two types of sympathetic chain ganglia

1. sympathetic chain ganglia (aka paravertebral ganglia) | 2. prevertebral ganglia

what neurotransmitter is used in preganglionic neurons? what does the parasympathetic postganglionic neuron use? what does the sympathetc postganglionic neuron use?

acetylcholine acetylcholine norepinephrine

where are the sympathetic preganglionic cell bodies

CNS thoracolumbar cord at T1-L3 later horns (gray matter)

what are the sympathetic preganglionics first couple steps

1. pregagnlionic axons exit the cord ventrally as ventral roots 2. enter the spinal nerve 3. go through the ventral primary ramus 4. travel through the white ramus communicans

what are the 3 steps that the sympathetic preganglionics can take

1. synapse there in the sympathetic chain of ganglia 2. go another area of the chain (up or down) before synapsing 3. leave to synapse in a prevertebral ganglion

what kind of fibers do gray rami communicans have? what about white rami communicans?

post-ganglionics (unmyelinated) | pre-ganglionics (thinly myelinated)

where are white rami communicans found? | where are gray rami communicans found

T1-L3 (thoracolumbar) | all spinal cord levels

what do white rami communicans contain? | what do gray rami communicans contain?

myelinated preganglionic sympathetic fibers | unmyelinated postganglionic sympathetic fibers

where does the oculosympathetic pathway begin? what does it begin w/?

in the hypothalamus w/ the "central neuron"

what do the first-order fibers do after they leave the hypothalamus

descend through the lateral brainstem (midbrain, pons, medulla) and cervical spinal cord

when the first order neurons reach the ciliospinal center of budge at spinal cord segments _________, the central neuron synapses onto the preganglionic cell bodies located in the _____

``` C8, T1, and T2 lateral horn (intermediolateral cell column) ```

where do the preganglionic neuron (2nd order neuron) eventually terminate/synapse in?

superior cervical ganglion

what are the 2 routes for postganglionic oculosympathetics

1. hitching a ride w/ nasociliary nerve (V1) in orbit | 2. through ciliary ganglion w/o synapse (unlike parasym to sphincter)

second preganglionic neurons exit ventral spinal roots and arch over apex of lung to ascend in ___________, synapsing in _______ and exiting as third-order neuron

cervical sympathetic chain | superior cervical ganglion

third order postganglionic neuron travels w/ _____ artery into ______ w/ ophthalmic branch of of CN5 joining nasociliary branch of CN5 or passes through the ______directly, reaching the eye as ______ and _____ ciliary nerves

carotid cavernus sinus ciliary ganglion short and long

what do preganglionic parasympathetic fibers arise from whta do they exit as what do they synapse at what do they reach the eye as

accessory oculomotor nucleus oculomotor nerve ciliary ganglion short ciliary nerves

what kind of tumor causes horners syndrome

apical lung tumor (pancoast tumor) bc preganglionic fibers pass by the lung apex (which is near the lower part of the brachial plexus)

``` parastympathetic brainstem nuclei CN3= ? CN7 =? CN9= ? CN10=? ```

edinger-westphal superior salivatory nucleus inferior salivatory nucleus dorsal motor nucleus of X

Lecture 2-spinal cord Flashcards

(63 cards)