Spinal Cord A & P Flashcards by Blake Miller

at what level does the spinal cord end

-what accounts for this disparity in length between the spinal cord and spine

L1-L2

differential growth of the spinal cord versus the vertebral column

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location of observable enlargements in size of spinal cord

-what do these enlargements indicate

cervical region
lumbar/sacral regions
marks the areas of the spinal cord that contain the neurons concerned with the upper and lower extremities

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cord continues into what

rostrally
caudally

rostrally
-medulla
caudally
-conus medullaris

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the dorsal and ventral roots of the lower lumbar and sacral segments continue caudally to exit…
-the collection of these long roots is the…

their appropriate intervetrebral foramina

cauda equina

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the dura mater consists of…

meningeal layer

-periosteal layer ends at foramen magnum

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epidural space is filled with…

fat

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arachnoid mater actions as the limiting component of…

CSF containment

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CSF gets into the subarachnoid space of the spinal canal after leaving the…

foramina of Luschka and Magendie

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what is the lumbar cistern

large pocket of subarachnoid space below the caudal tip of the cord

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where are spinal taps usually made

-another name for spinal tap

in lumbar cistern

aka lumbar puncture

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pia components

pia intima
-adhered directly to the spinal cord
pia externa
-forms the denticulate ligaments

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what are the denticulate ligaments

-purpose

extensions of the pia that protrude from the lateral sides of the cord and pierce the arachnoid to attach to the dura
help anchor and stabilize the cord in the vertebral canal

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what is filum terminale

ligaments at caudal end of conus medullaris that extends to anchor the cord

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filum terminale

-conposition

pia
glial elements
maybe some remnants of coccygeal neuronal elements

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as the filum terminale extends through and is encased with the dura to attach to the coccyx, it is termed…
-function

coccygeal (sacral) ligament

anchors end of the cord in the spinal canal

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gray matter consists of…

neuron cell bodies

glial cells

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white matter consists of…

myelinated axons

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white matter contains…

-these can be divided into what general locations

dorsal (posterior) funiculus
lateral funiculus
ventral (anterior) funiculus

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funiculus

general term for…
each funiculus is composed of….

general term for an area of white matter

composed of a number of specific named tracts

the naming of each specific pathway in a funiculus can be…

descriptive of location within the transverse section of the spinal cord
may also give an indication of what areas within the CNS the pathway is connecting

important regions of the gray matter (with laminae numbering)

Lissauer’s tract (dorsolateral tract of Lissauer)
dorsal horn: substantia gelatinosa (II)
dorsal horn: nucleus proprium (III, IV)
dorsal nucleus of Clarke (VII, in part)
intermediolateral cell column or lateral horn (IX, in part)
ventral horn: location of the lower motor neurons (IX, in part)

Dorsal nucleus of Clarke segmental levels

T2-L2

intermediolateral cell column or lateral horn segmental levels

C8/T1-L2

S1-S3

dorsal horn is concerned with…

incoming sensory information

there is a _____ organization of the fibers than enter the cord via the dorsal root

medial to lateral

dorsal root - more medially situated fibers are..... - more laterally situated fibers are...

medial -large diameter, heavily myelinated (Ia/b, A-alpha, II) laterall -small diameter, non-myelinated C fibers

dorsal root - fibers of intermediate caliber that are finely myelinated lie... - what ones are these

between the large and small diameter fibers | a-delta

ventral horn contains - these are knows as - this is the...

cell bodies with axons that will leave the spinal cord and innervate muscles lower motor neurons Final Common Pathway for information that is needed to make a muscle do its thing

what are the two types of lower motor neurons within the ventral horn

alpha-motor neurons | gamma-motor neurons

how are alpha and gamma motor neurons situated in the ventral horn

medially situated are concerned with axial musculature laterally situated innervated muscles of the extremities posteriorly situated are concerned with flexion anteriorly situated are concerned with muscles of extension

spinal nerve formed from...

merging of the dorsal and ventral roots

associated with the spinal nerves at spinal cord levels T1-L2 is a series of... -these are the location of...

autonomic ganglia | these ganglia are the location of the postganglionic cell bodies for the SNS

where are the preganglionic cell bodies located

lateral horn in the spinal cord | -intermediolateral cell column

what are reflexes

specific, stereotypes motor responses ta an adequate stimulus

reflexes require a series of structures consisting of at least what components

receptor afferent limb efferent limb effector organ

reflexes | -receptor examples

muscle spindle GTOs encapsulated and free nerve endings

reflexes | -afferent limb function, example

carries the impulse (stimulus) into the CNS | i.e. dorsal root fibers

reflexes | -efferent limb function, example

carries the impulse for the response out of the CNS | i.e. lower motor neuron (alpha-motor neuron)

reflexes | -effector organ examples

skeletal muscle | glands

stretch reflex/deep tendon reflex (DTR) - example - demonstrates principles of...

patellar ligament example demonstrates -autogenic facilitation -reciprocal inhibition

Hoffman (H-reflex) - elicited with... - what happens - used to test...

elicited with a low frequency stimulation of the Ia fibers of the muscle spindle (activation without stretch) this stimulation then results in muscle contraction of the muscle used to test the integrity of the monosynaptic connections within the spinal cord

tendon organ reflex - how does it occur - demonstrates what principles

GTO stimulus at a certain point of increased tension, the stimulus generates an inhibitory influence to the a motor neurons that are driving the contracting muscle, demonstrating the principle of autogenic inhibition muscle can now relax through the interneuronal pool, the antagonistic muscle can be activated to facilitate the release of tension, reciprocal facilitation

flexor withdrawal reflex and crossed extension reflex | -what occurs

reciprocal inhibition of antagonist or opposing muscle masses must occur recurrent inhibition -(Renshaw cells) same muscle and synergists non-reciprocal inhibition - inhibits agonists, synergists and antagonists (coordination of various movements)

segmental loss involves...

strucutures that are present at the specific segmental level -includes the gray matter areas of the cord and to some extent the dorsal and ventral root components that are bringing in sensory information and/or sending out motor information

segmental loss - generally does not refer to... - in the real world however...

does not refer to the additional involvement of ascending or descending white matter pathways in the real world, segmental losses will most likely include some involvement of the white matter