Spinal Cord and Reflexes Flashcards by Zhannia Kyda Villarmino

There are 31 pairs of spinal nerves. How many are in each spinal segment [Cervical, Thoracic, Lumbar, Sacral, Coccygeal]?

Cervical: 8
Thoracic: 12
Lumbar: 5
Sacral: 5
Coccygeal: 1

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C1-C7 exits above or below their respective vertebrae?

Above

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C8 exits between which vertebraes?

Between C7 and T1

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T1 and below exits above or below their respective vertebrae?

Below

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Central Relay Station

A. receives incoming information from the body and the brain
B. conveys outgoing information to the body and the brain

A. receives incoming information from the body and the brain

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Central Processing Station

A. receives incoming information from the body and the brain
B. conveys outgoing information to the body and the brain

B. conveys outgoing information to the body and the brain

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Conus Medullaris

conical distal end of the SC

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Cauda Equina

horse’s tail; bundle of spinal nerves and spinal nerve rootlets; made up of dorsal and ventral

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Filum Terminale

extends from the tip of conus and attaches to the distal dural sac; anchors the conus medullaris and the tecal sac of the first coccygeal vertebrae which limits the superior movement and the extension of pia mater

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Denticulate Ligaments

connected tissue extending form the lateral side of the spinal cord to the dura mater by tooth-like processes; limits lateral movement

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Cervical Enlargement

origin of the brachial plexus

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Lumbosacral Enlargement

origin of lumbosacral plexus

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Epidural Space

separates dura mater from vertebral column, anesthetic can be injected to anesthetize the local spinal nerve

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Dura Mater

Outermost, thickest

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Subdural Space

a potential space that can be opened by the separation of the arachnoid mater from the dura mater as the result of trauma

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Arachnoid Mater

very thin

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Subarachnoid Mater

usually contains the CSP, extends to the S2 level of vertebra

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Pia Mater

deepest

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What are the 6 meningeal coverings of the spinal cord?

Epidural space, Dura mater, subdural space, arachnoid mater, subarachnoid mater, and pia mater

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At birth, the cord extends at what level?

3rd lumbar vertebrae

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At the adult stage, the tip of the cord lies at what level?

1st/2nd level of the vertebrae

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Divides the cord into symmetric right and left portions

Anterior Median Fissure
Posterior Median Sulcus

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The spinal cord is continuous with the medulla oblongata and starts from the level of foramen magnum and will extend up to an adult’s

lower border of L1 vertebra

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The spinal cord is continuous with the medulla oblongata and starts from the level of foramen magnum and will extend up to a young child’s

upper border of L3 vertebra

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The anterior median fissure contains a fold of pia and blood vessels and its floor is the

Anterior (white) Commissure

Ventral nerve roots

Anterior exits at the anterolateral sulcus

Dorsal nerve roots are

Posterior attached to the spinal cord along a shallow vertical groove, the posterolateral sulcus

Dorsal Root Ganglion

swelling that contains nerve cell bodies that gives rise to the sensory axons

Peripheral Nerves

portions of the spinal nerve outside the vertebral column

Dorsointermediate Sulcus

responsible for dividing the dorsal column into fasciculus gracilis (lower extremities, medial) and fasciculus cuneatus (upper extremities, lateral)

Dorsolateral Sulcus

contains the vertebral grove which is where the dorsal nerve rootlets are attached

Ventrolateral Sulcus

where the ventral nerve roots exit

LAW OF BELL AND MAGENDIE

principle referring to the separation of the sensory and motor neurons of the spinal cord implicating that impulses are relayed in one direction

Dorsal Spinal roots are _____ and Ventral Spinal roots are_______

sensory; motor

Alpha Motor Neuron Axon

attached to the extrafusal (large) striated muscle fibers Anterior Root

Gamma Motor Neuron Axon

supplies the intrafusal muscle of the muscle spindle for muscle tone; responsible for regulating the sensitivity of the muscle spindle Anterior Root

Sclerotomes

consists of bones and ligaments innervated by one spinal nerve

Dermatomes

skin area supplied by a spinal nerve keyword: derma

Dermatomes

skin area supplied by a spinal nerve keyword: derma

Myotomes

group of muscles innervated by a spinal nerve

The Internal Anatomy of the Spinal Cord has:

gray matter, white matter, cervical and lumbar enlargement

Gray Matter

periphery comprised of axons Made up of two symmetric portions joined centrally by the gray commissure

White Matter

“Law of Bell & Magendie”

needed in order to innervate the muscles of arms (cervical) and legs (lumbar); as one travels inferiorly down the cord, the amount of white mater decreases as less information is being transmitted

Gray commissure

transverse connection of gray matter

The gray matter has 3 columns, they are:

Ventral Horn, Dorsal Horn, and Intermediolateral Horn

Ventral Horn

in front of the central canal, contains cells of the origin of the ventral root (alpha and gamma) and cell bodies innervating the skeletal muscles (LMN); concerned with motor function

Intermediolateral horn

between dorsal and ventral gray matter, contains preganglionic autonomic cells (ANS)

Intermediolateral horn

between dorsal and ventral gray matter, contains preganglionic autonomic cells (ANS)

Dorsal horn

contains the dorsolateral fasciculus (Lissauer’s tract – pain pathway); concerned with sensory

Lamina processes

receive information from the brain or effector organs that process either sensory or motor info depending on location

Substantia Gelatinosa (RL 1&2)

for pain sensation

Nucleus Proprius (RL 3&4) and Nucleus Dorsalis (RL7)

for proprioception

Anterior Horn Cell (RL 9)

for movement

Central Canal (RL10)

circulation of CSF

There are how many Rexed's Lamina in the gray matter of the spinal cord?

* Respond to noxious (pain) stimuli * Send axons to the contralateral spinothalamic tract * Has high concentration of substance P (a neuropeptide involved in pathways mediating sensibility to pain) | Contains: Nuclei reticular formation

Lamina I | *Dorsomarginal nucleus*

Responds to noxious stimuli and has high concentration of substance P | Contains: Predominantly Golgi Type II neurons

Lamina II | *Substantia Gelatinosa*

Responds to noxious stimuli and has high concentration of substance P | Contains: Predominantly Golgi Type II neurons

Lamina II | *Substantia Gelatinosa*

Conveys position and light touch

Lamina III and IV | *Nucleus Proprius*

Responds to both noxious and visceral afferent stimuli

Lamina V

Respond to mechanical signals from joints and skin | Contains exteroceptive and proprioceptive sensory cells

Lamina VI

* Nucleus dorsalis of Clarke (to posterior spinocerebellar tract) * Interomediolateral Horn * Sacral parasympathetic nucleus of Onufrowicz | Lamina for proprioception

Lamina VII | *Nucleus Dorsalis or Clarke's Column*

* Receives descending axons from brain * Medial motor neuron column: axial musculature * Lateral motor neuron column: arm and leg * Flexor muscles are innervated by motor neurons near the central canal * Extensors are innervated by motor neurons more laterally | Contains Alpha and gamma motor neurons

Lamina VIII and IX

Represents the small central neurons around the central canal

Lamina X | *Central Canal*

What are the 3 columns (funiculi) of white matter?

Posterior, Lateral, Ventral (Anterior)

This is between Dorsal Median Fissure and Dorsal Horn and where the fasciculus cuneatus and fasciculus gracilis are located

Posterior Column

This is between Dorsal Median Fissure and Dorsal Horn and where the fasciculus cuneatus and fasciculus gracilis are located

Posterior Column

between Ventral Horn and Dorsal Horn

Lateral Column

between Ventral Median Fissure and Ventral Horn

This tract is sensory and goes towards the CNS

Ascending tracts

This tract is motor and goes towards the PNS

Descending tracts

First-Order Neuron | Descending Tract

UMN | from cerebral cortex

Second-Order Neuron | Descending Tract

Interneuron (within the gray column, a relatively short neuron)

Third-Motor Neuron | Descending Tract

LMN ## Footnote innervation of the skeletal muscles through the anterior root of spinal cord

First-Order neuron | Ascending tract

comes from the dermatomes or sensory receptors and ends at Dorsal Root Ganglion

Second-Order neuron | Ascending tract

gives rise to axons that decussates and ascends to a higher level of the CNS where it synapses on the third order neurons at dorsal horn.

Third-Order neuron

usually gives rise to a projection fiber that goes to the cortex at thalamus

Third-Order neuron

usually gives rise to a projection fiber that goes to the cortex at thalamus