spinal cord - back anatomy Flashcards by Unknown Unknown

What membranes surround the spinal cord?

meninges

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Where is the spinal cord in adults?

from the foramen magnum to the inferior border of the first lumbar vertebra

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Where is spinal cord derived from?

from the caudal part of the neural tube

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Where is the spinal cord in newborns?

from the foramen magnum to the third lumbar vertebra

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Where does the spinal cord lie that extends caudally to the level of the second sacral vertebra?

subarachnoid space

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Spinal cord is continuous with the __ __ at the spinomedullary junction, a plane defined by three structures.

medulla oblongata

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Where does the spinal cord suspend and anchor?

within the dural sac

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Where does the spinal cord arise which closely invests the spinal cord?

pia mater

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Two flattened bands of pial tissue that attach to the spinal dura comprising 21 pairs of tooth-shaped extensions

Denticulate ligaments

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An extension of pia mater that extends from the conus medullaris to the dural sec (internus) and from the dural sec to the coccyx (externus)

Filum terminale

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Provide strong anchorage and fixation of the spinal cord to the vertebral canal

Spinal nerve roots

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Where are the enlargements for the nerve supply of the upper and lower extremities?

Cervical (C5-T1)

Lumbar (L1-S2)

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Spinal cord terminates caudally as the __ __

conus medullaris

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What sensory fibers does the spinal nerves have?

Contain both motor and sensory fibers

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What nerves do not have posterior roots nor corresponding dermatomes?

coccygeal nerve

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What is the sensory fiber of C1 and coccygeal nerve?

pure motor

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With the exception of C1, where do spinal nerves exit the vertebral canal ?

intervertebral or sacral foramina

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All other nerve exits below, except the __

C1-C7

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Where does the spinal cord end in adults?

at lower border of L1-L2 vertebrae

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Where does the spinal nerve terminate in adults?

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Where does the spinal nerve terminate in newborns?

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Where does the subarachnoid space extend?

to lower border of S2 vertebra

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Where is lumbar puncture usually performed?

L3-L4 or L4-L5 (level of coda equina)

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What is the goal of lumbar puncture?

to obtain sample of CSF without damaging spinal cord

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Where does epidural anesthesia stop?

epidural space

What layer of the meninges does the needle not pass through?

pia mater

Convey sensory input from skin, muscle, bone, and joints to the central nervous system

General somatic afferent (GSA) fibers

Convey sensory input from visceral organs to the CNS

General visceral afferent (GVA) fibers

Convey motor output from anterior horn motor neurons to skeletal muscle

General somatic efferent (GSE) fibers

Convey motor output from intermediolateral cell column neurons, via paravertebral or prevertebral ganglia, to glands, smooth muscle, and visceral organs

General visceral efferent (GVE) fibers

Convey motor output from the sacral parasympathetic nucleus to the pelvic viscera via intramural ganglia

General visceral efferent (GVE) fibers

Formed by the union of posterior and anterior roots within the intervertebral foramen, resulting in a mixed nerve

spinal nerve

Enters the posterior lateral sulcus as posterior rootlets and conveys sensory input from the body via spinal ganglion

Posterior root

Located within the posterior root and within the intervertebral foramen

Spinal ganglion

Contains pseudounipolar neurons of neural crest origin that transmit sensory input from the periphery (GSA and GVA) to the spinal cord via posterior roots

Spinal ganglion

Emerges as anterior rootlets from the anterior lateral sulcus and conveys motor output from visceral and somatic motor neurons

Anterior root

Consists of lumbosacral (posterior and anterior) nerve roots (L2-Co) that descend from the spinal cord through the subarachnoid space to exit through their respective intervertebral or sacral foramina

Cauda equina

Why is coda equina named as such?

because it looks like a horse tail

innervates the skin and muscles of the back

Posterior ramus

innervates the anterior and lateral muscles and skin of the trunk, extremities, and visceral organs

Anterior ramus

innervates the meninges and vertebral column

Meningeal ramus

contain unmyelinated postganglionic sympathetic fibers

Gray communicating rami

contain myelinated preganglionic sympathetic fibers and myelinated GVA fibers (splanchnic nerves)

White communicating rami

It is associated with all spinal nerves

Gray communicating rami

It is found only in thoracolumbar segments of the spinal cord (T1-L2)

White communicating rami

• Consists of a cutaneous area innervated by the fibers of one spinal nerve

Dermatome

Consists of muscles innervated by the fibers of one spinal nerve

Myotome

Consists of bones and ligaments innervated by the fibers of one spinal nerve

Sclerotome

Landmark dermatome for C2

posterior half of skull

Landmark dermatome for C6

thumbs

Landmark dermatome for C7

middle finger

Landmark dermatome for C8

little finger

Landmark dermatome for T4

nipple

Landmark dermatome for T7

xiphoid process

Landmark dermatome for T10

umbilicus (belly button)

Landmark dermatome for C4

low-collar shirt

Landmark dermatome for L1

Inguinal Ligament

Landmark dermatome for L4

kneecaps

Landmark dermatome for S2, S3, S4

penile and anal zones

Myotome landmark for C5

elbow flexors - biceps - brachialis - brachioradialis

Myotome landmark for C6

wrist extensors | - extensor carpi radialis longus and brevis

Myotome landmark for L2

hip flexors | - illiopsoas

Myotome landmark for L3

knee extensors | - quadriceps

Myotome landmark for L4

ankle dorsiflexors | - tibialis anterior

Myotome landmark for L5

long toe extensors | - extensor hallucis longus

Myotome landmark for S1

ankle plantar flexors | - gastrocnemius, soleus

Myotome landmark for C7

elbow extensors | - triceps

Formed by a great lash of dorsal and ventral roots of the lumbar and sacral spinal nerves that surround the filum terminale

Coda Equina ("Horse's Tail")

Lateral extensions of the spinal pia mater, consisting of 21 pairs of toothpick-like processes

Denticulate Ligaments

A prolongation of the pia mater from the tip (conus medullaris) of the spinal cord at the level of L2

Filum Terminale (Internum)

Contained in the subarachnoid space between the arachnoid and pia mater

Cerebrospinal Fluid

Enters spinal cord via subarachnoid space

Cerebrospinal Fluid

What Rexed laminae of the spinal cord gray matter surrounds the central canal?

Toward the center of the spinal cord

Gray matter

Butterfly- or H-shaped that varies according to the spinal cord level

Gray matter

Gray matter is divided into cytoarchitectural areas called __

Rexed laminae

what are the three horns or cell columns of the gray matter?

Dorsal horn Intermediate gray Ventral horn

Which | Rexed laminae are found in the posterior horn?

Rexed laminae I-VI

What illness is associated with the damaged anterior gray horn?

Poliomyelitis

What is the condition of polio?

a person cannot move because of lacking acetylcholine needed for the action potential of muscles

Which Rexed laminae are found in the anterior horn?

VII, VIII, IX

Contains a central canal

Gray matter

Consists of bundles of myelinated fibers that surround the central gray matter

White matter

Consists of ascending and descending fiber pathways called tracts

White matter

What divides the white matter bilaterally into three major divisions?

sulci

• Located between the posterior median sulcus and the posterior lateral sulcus

Posterior funiculus

Where is Posterior funiculus subdivided into two fasciculi?

above T6

Located between the posterior median sulcus and posterior intermediate sulcus and septum

Fasciculus gracilis

Located between the posterior intermediate sulcus and septum and posterior lateral sulcus

Fasciculus cuneatus

Found only at the upper thoracic and cervical cord levels (C1-T6) and affects the Upper extremity

Fasciculus cuneatus

Found at all cord levels affects the Lower extremity

Fasciculus gracilis

Located between the posterior lateral and anterior lateral sulci

Lateral funiculus

Located between the anterior median fissure and anterior lateral sulcus

Anterior funiculus

What does ascending tracts transfer?

Sensory

What does descending tracts transfer?

Motor

(Fine touch, proprioception, vibration)

Doral Columns

(pain and temperature)

Lateral Spinothalamic Tract

(light touch)

Ventral Spinothalamic Tract

What are the descending tracts?

Lateral and Anterior Corticospinal Tract