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Neuroscience - spring 2024 > lec 4 - spinal cord gross anatomy and vasculature > Flashcards

lec 4 - spinal cord gross anatomy and vasculature Flashcards

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1
Q

Cervical Region

A

8 spinal levels and 8 spinal nerves, but only 7 cervical vertebrae.

The nerves of the same number of the vertebrae exit above their respective vertebrae:
> C1-C7: exit superior to vertebral level
> C8: exits inferior to C7 vertebra

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2
Q

Thoracic region

A

12 spinal levels, 12 spinal nerves, and 12 vertebrae

all the thoracic spinal nerves to exit below their respective vertebral levels

L1-L5: exit inferior to vertebral level

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3
Q

Lumbar region

A

5 spinal levels, 5 spinal nerves, and 5 vertebrae

All lumbar spinal nerves exit below their respective vertebrae

L1-L5: exit inferior to vertebral level

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4
Q

Sacral region

A

5 spinal levels, 5 spinal nerves, and 5 vertebrae that are fused together to form the sacrum

Sacral spinal nerves exit below their respective vertebrae

S1-S5: exit via sacral foramina or sacral hiatus

S1-S4 ventral rami exit out of the anterior sacral foramina.

S1-S4 dorsal rami exit out of the posterior sacral foramina.

The S5 spinal nerve exits out of the sacral hiatus with the coccygeal spinal nerve

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5
Q

coccygeal region

A

1 spinal level, 1 spinal nerve, and 1-5 fused vertebrae to form the coccyx

The coccygeal spinal nerve exits with the 5th sacral spinal nerve through the sacral hiatus

Co1: exits via sacral hiatus

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6
Q

Spinal levels do not line up with vertebral levels =

A

due to differential growth during embryonic development

spinal cord finished development before the vertebral column because the nervous system is one of the first systems to develop

vertebral column continues to grow and develop after the spinal cord has finished development

vertebral column is longer than the spinal cord

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7
Q

Herniated Discs

A

Most common regions: cervical and lumbosacral

For cervical and lumbosacral disc herniations, the spinal nerve involved typically corresponds to the lower of the adjacent 2 vertebrae

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8
Q

Cervical nerve roots have a fairly horizontal pathway as they exit the intervertebral foramen =

A

posterior longitudinal ligament strengthens the central portion of the intervertebral disc

herniations typically occur laterally rather than centrally

usually involves the nerve root that corresponds to the lower vertebral bone of the herniated disc (e.g., C5-C6 disc herniation usually results in C6 radiculopathy)

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9
Q

Lumbar nerve roots must descend prior to exiting through the intervertebral foramen

A

As the nerve roots are about to exit, they move into the lateral recess of the spinal canal

posterolateral disc herniation in the lumbosacral region usually impinges nerve roots on their way to exit beneath the next lower vertebra, which correspond to the number of the nerve root involved (e.g., L5-S1 disc herniation usually results in S1 radiculopathy)

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10
Q

Cervical enlargement

A

C5-T1 spinal levels = brachial plexus

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11
Q

Lumbosacral enlargement

A

L1-S3 spinal levels = lumbosacral plexus

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12
Q

Conus medullaris

A

End of spinal cord

Occurs between vertebral levels L1-L2

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13
Q

Cauda equina

A

Collection of spinal nerve rootlets that extends beyond conus medullaris

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14
Q

Cauda Equina Syndrome (CES)

A

Impaired function of multiple nerve roots below L1 or L2

Depending on the level of injury, symptoms may include sensory and motor deficits in the lower limb, urinary incontinence, fecal incontinence, and sexual incontinence

Detecting and treating CES early is critical to avoid irreversible deficits

Common causes of CES include lumbar disc herniation, schwannoma, meningioma, meningitis, and trauma

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15
Q

Compression of the conus medullaris causes ___, which has similar symptoms

A

conus medullaris syndrome

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16
Q

Spinal nerve rootlets

A

Ventral rootlets: motor
Dorsal rootlets: sensory

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17
Q

The dorsal roots and rootlets carry ___ information into the ___ gray horn of the spinal cord

A

sensory

dorsal

(sensory pathway)

purely sensory input pathways transmitting information in only one direction (toward the spinal cord)

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18
Q

The ventral rootlets and roots carry ___ information out from the ___ gray horn of the spinal cord

A

motor

ventral

(motor pathway)

The ventral rootlets and roots are purely motor output pathways transmitting information in only direction (away from the spinal cord)

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19
Q

The dorsal and ventral roots converge to form the ___

A

spinal nerve (trunk)
= both a sensory and motor pathway (mixed nerve) carrying information in both directions (toward and away from the spinal cord)

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20
Q

Spinal nerve roots

A

Ventral roots: motor
Dorsal roots: sensory
Dorsal root ganglion

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21
Q

Spinal nerve (trunk)

A

Motor and sensory

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22
Q

dorsal ramus =

A

carries sensory and motor information to and from the intrinsic/deep/epaxial back muscles

both a sensory and motor pathway carrying information in both directions (toward and away from the spinal cord)

intrinsic/deep/epaxial back muscles are derived from the epimere of the somite, which the dorsal ramus migrated into during embryonic development

innervates the skin overlying the intrinsic/deep/epaxial back muscles (the skin overlying the vertebral column)

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23
Q

ventral ramus =

A

carries sensory and motor information to and from the rest of the trunk and limb muscles

both a sensory and motor pathway carrying information in both directions (toward and away from the spinal cord)

Communicating rami = Connection to sympathetic trunk

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24
Q

Dermatomes

A

portion of skin innervated by a single spinal level

Sensory region of skin innervated by a single nerve root

C1 spinal segment does not have a dermatome

Trigeminal nerve (CN V) provides sensory innervation to the face

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25
Notice in the chest that the C5 dermatome meets up with the T1 dermatome
This is because the C6, C7, and C8 dermatomes get pulled into the upper limbs
26
There is overlap in areas of the body that are supplied by specific dermatomal levels
injury to one spinal level often does not cause complete lack of sensation in that dermatome it often leads to decreased sensation in that dermatome pinprick test is a good test for dermatomal level integrity because it is more precise and activates smaller nerve fibers
27
Dermatomes vs. Cutaneous Fields
dermatomes are the sensory distribution of single spinal levels cutaneous fields are the sensory distribution of peripheral nerves
28
Myotomes
group of muscles innervated by a single spinal nerve root
29
PNS Plexuses
cervical plexus brachial plexus lumbosacral plexus
30
Cervical plexus:
formed by cervical ventral rami (C1-C4) Provides sensory and motor innervation to the neck and part of the head
31
Brachial plexus:
formed by cervical and thoracic ventral rami (C5-C8 and T1) Provides sensory and motor innervation to the upper limb
32
Lumbosacral plexus:
formed by lumbar, sacral, and coccygeal ventral rami (L1-L5, S1-S5, and Co1) Provides sensory and motor innervation to the lower limb and part of the pelvis
33
Somatic division
Target/effector: skeletal muscle 1 motor neuron pathway Cell body in CNS
34
Autonomic division
Target/effector: smooth muscle, cardiac muscle, and glands 2 motor neuron pathway Preganglionic (presynaptic) neuron = Cell body in CNS Postganglionic (postsynaptic) neuron = Cell body in PNS
35
Somatic motor neuron cell bodies are located in the ventral horn of the spinal cord =
Follow spinal nerve anatomy to effector (skeletal muscle)
36
Somatic/general sensory neurons have receptors in skeletal muscle, skin, hair, nails, some mucosa, etc. =
Follow spinal nerve anatomy to dorsal horn of spinal cord Cell bodies located in the dorsal root ganglion
37
Autonomic Nervous System
In general, the sympathetic and parasympathetic divisions of the ANS target the same organs, but they typically have opposing actions/effects The ANS targets involuntary muscle (cardiac and smooth muscle) in viscera, thus the sympathetic and parasympathetic divisions modulate the activity of these viscera
38
Sympathetic division
Origin: thoracolumbar (T1-L2/L3) spinal levels
39
sympathetic neurons:
Sympathetic preganglionic neurons > Arise in the lateral horn of the spinal cord at T1-L2/L3 > Release acetylcholine (ACh) Sympathetic postganglionic neurons > Arise in sympathetic trunk ganglia or collateral ganglia > Most release norepinephrine (NE), some release ACh
40
Sympathetic trunk/chain
Located on either side of vertebral column from cervical to sacral regions Transmits preganglionic and postganglionic sympathetic fibers
41
Sympathetic trunk/chain (paravertebral) ganglia
Swellings on sympathetic trunk Motor ganglia: synapse location for preganglionic and postganglionic sympathetic fibers The swellings/ganglia on the sympathetic trunk/chain is formed from the postganglionic sympathetic neuron cell bodies
42
Parasympathetic division
Origin: craniosacral Cranial nerve nuclei in the brainstem and in the sacral spinal cord (S2-S4)
43
Parasympathetic neurons:
Parasympathetic preganglionic neurons > Arise from cranial nerve nuclei in the brainstem and from the lateral horn of the spinal cord at S2-S4 > Release ACh Parasympathetic postganglionic neurons > Arise in the wall of the organ (in terminal ganglia) > Release ACh
44
Gray matter of the spinal cord
Internal Neuronal cell bodies and synapses The gray matter is at the center of the spinal cord, surrounded by white matter (the gray matter resembles the shape of a butterfly). The gray matter is where synapses occur in the spinal cord (integration of information).
45
White matter of the spinal cord
External Neuronal axons The white matter allows information to travel up and down the spinal cord and from right to left in the spinal cord.
46
Gray Matter of the Spinal Cord - Dorsal horn
Present at all spinal levels Somatic sensory and visceral sensory
47
Gray Matter of the Spinal Cord - Ventral horn
Present at all spinal levels Somatic motor
48
Gray Matter of the Spinal Cord - Lateral/Intermediate horn
Present at T1-L2/L3 (sympathetic) and S2-S4 (parasympathetic) spinal levels Autonomic/visceral motor
49
Dorsal gray commissure:
connects right and left dorsal horns Dorsal to central canal
50
Ventral gray commissure:
connects right and left ventral horns Ventral to central canal
51
Dorsal Root Entry Zone
where sensory neurons enter the spinal cord
52
Medial DREZ:
where large, myelinated sensory neurons carrying somatosensation and proprioception enter the spinal cord Afferents from mechanoreceptors
53
Lateral DREZ/Lissauer’s tract:
where small unmyelinated or lightly myelinated sensory neurons carrying pain enter the spinal cord Afferents from nociceptors, thermoreceptors, and viscera
54
Gray Matter Nuclei
DORSAL HORN: 1) Postero(marginal) zone/ nucleus 2) Substantia gelatinosa 3) Nucleus proprius 4) Column of Clarke/Clarke’s nucleus/nucleus dorsalis LATERAL HORN: 5) Intermediolateral cell column (IMLCC)/lateral horn VENTRAL HORN: 6) Motor nuclei
55
Postero(marginal) zone/ nucleus
location: dorsal horn of all spinal levels function: pain and temp synapses: primary afferent fibers conveying pain and temp synpases with 2nd order neuron dendrites inputs/projections: 2nd order neurons with their dendrites in this nucleus project into the contralateral anterolateral system/spinothalamic tracts
56
Substantia gelatinosa
location: dorsal horn of all spinal levels function: pain modulation synapses: primary afferent fibers conveying pain and temp synapse with dendrites of 2nd order neuron whose cell bodies are in the nucleus proprius - cell bodies are interneurons that release enkephalin inputs/projections: dendrites of the 2nd order neurons with their cell bodies in the nucleus proprius, project into contralateral anterolateral system/spinothalamic tracts - enkephalinergic interneurons that modulate pain
57
Nucleus proprius
location: dorsal horn of all spinal levels function: pain and temperature synapses: nucleus contains 2nd order neuron cell bodies whose dendrites extend into the substania gelatinosa to synapse with primary afferent fibers conveying pain and temp inputs/projections: 2nd order neurons with their cell bodies in this nucleus project into the contralateral anterolateral system/spinothalamic tracts
58
Column of Clarke/Clarke’s nucleus/nucleus dorsalis
location: dorsal horn of C8-L3 spinal levels function: proprioception (unconscious) synapses: primary afferent fibers conveying proprioception synapse with 2nd order neuron cell bodies inputs/projections: 2nd order neurons with their cell bodies in this nucleus project into the ipsilateral dorsal spinocerebellar tract
59
Intermediolateral cell column (IMLCC)/lateral horn
location: T1-L2/L3 and S2-S4 spinal levels function: autonomic motor synapses: contains cell bodies of preganglionic sympathetic neurons at T1-L2/L3 and preganglionic parasympathetic neurons at S2-S4 inputs/projections: receives input from descending pathways from the brainstem and diencephalon
60
Motor nuclei
location: ventral horn of all spinal levels function: somatic motor synapses: contains lower motor neuron cell bodies for skeletal muscle contraction inputs/projections: receives input from spinal reflexes and descending motor pathways
61
Ventral horn topography and lower motor neuron (LMN) organization
Medial LMNs innervate proximal/axial muscles Lateral LMNs innervate distal limb muscles Ventral LMNs innervate extensor muscles Dorsal LMNs innervate flexor muscles
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White Matter of the Spinal Cord
Dorsal column/funiculus Ventral column/funiculus Lateral column/funiculus
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Dorsal column/funiculus =
Contains ascending sensory tracts/ fasciculi
64
Ventral column/funiculus =
Contains mostly descending motor tracts/fasciculi
65
Lateral column/funiculus =
Contains ascending sensory and descending motor tracts/fasciculi
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Sulci of the Spinal Cord
Dorsal median sulcus/fissure Dorsal intermediate sulcus Dorsolateral sulcus Ventral median sulcus/fissure Ventrolateral sulcus All of these sulci run longitudinally on the external surface of the spinal cord
67
The posterior/dorsal median fissure/sulcus is at the midline and separates the ___
right and left dorsal columns there is one dorsal median sulcus
68
The posterior/dorsal intermediate sulcus/fissure is ___ to the dorsal median sulcus There are two dorsal intermediate sulci (right and left). Each sulcus separates the dorsal column into two tracts:
lateral gracile tract and cuneate tract
69
The posterolateral (dorsolateral) sulcus/fissure is lateral to the __ sulcus and is in the region of the ____
dorsal intermediate dorsal root entry zone There are two dorsolateral sulci (right and left). The posterior spinal arteries travel in each of the dorsolateral sulci.
70
The ventrolateral (anterolateral) sulcus/fissure is lateral to the ____ and is the exit point for the ventral rootlets as they leave the ventral horn
ventral median sulcus There are two ventrolateral sulci (right and left)
71
Blood Supply of the Spinal Cord
> Posterior spinal arteries > Anterior spinal artery
72
Posterior spinal arteries =
2 posterior spinal arteries in dorsolateral sulci Supply posterior 1/3 of spinal cord = Dorsal horns and dorsal columns
73
Anterior spinal artery =
1 anterior spinal artery in ventral median fissure Supplies anterior 2/3 of spinal cord = Ventral and lateral horns and ventral and lateral columns
74
Venous Drainage of the Spinal Cord
The internal and external vertebral venous plexuses drain blood from the spinal cord and vertebral column The external vertebral venous plexus is in the epidural space The internal vertebral venous plexus is in the subarachnoid space

Neuroscience - spring 2024 (10 decks)

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