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The Spinal Cord  Structure of the spinal cord Tracts of the spinal cord Spinal cord syndromes . Nabeel Kouka, MD, DO, MBA www.brain101.info. Spinal Cord. - Comparable to Input-Output (IO) System of the Computer - Spinal Nerve (C8, T12, L5, S5, Cx1)

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slide1

The Spinal Cord

      •  Structure of the spinal cord
      • Tracts of the spinal cord
      • Spinal cord syndromes

Nabeel Kouka, MD, DO, MBA

www.brain101.info

slide2

Spinal Cord

- Comparable to

Input-Output (IO) System of the Computer

- Spinal Nerve (C8, T12, L5, S5, Cx1)

- Segmental Structure of Neural Tube Origin

slide3

Spinal segment

C8, T12, L5, S5, Cx1

Anterior (Ventral) Root

Posterior (Dorsal) Root

Dorsal Root (Spinal) Ganglion

Root - Rootlets

slide4

Conus Medullaris (L1-2)

Cauda Equina

Anterior median fissure

Anterolateral fissure

slide5

Posterior

median sulcus

Posterolateral

sulcus

Posterior

intermediate

sulcus

Fasciculus

cuneatus

Fasciculus

gracilis

Posterior surface of the spinal cord

slide6

Spinal Cord Meninges

Periosteum of Vertebra

- Epidural Space ----------------- epidural anesthesia

Dura Mater Spinalis

Arachnoid Membrane

- Subarachnoid Space -------- Lumbar Puncture

Spinal Anesthesia

Pia Mater Spinalis

- Denticulate Ligament --------- Cordotomy

- Filum Terminale

slide7

Meninges of

  • the spinal cord
    • Dura mater
    • Arachnoid membrane
    • Pia mater

Denticulate ligament

- specialization of the pia mater

- landmark for cordotomy

slide11

Spinal Cord Vascular Supply

Arterial Supply

- Spinal Arteries

Anterior (1) & Posterior (2) Spinal Artery

from Vertebral artery

- Radicular Arteries ----- Segmental arteries

from Vertebral, Ascending Cervical, Intercostal and

Lumbar Artery

Venous Drainage

- Longitudinal & Radicular Veins

to Intervertebral veins ---- to Internal Vertebral Venous Plexus

to external vertebral venous plexus ---- to segmental veins

slide12

5. Adamkiwicz artery

anterior spinal artery segmental arteries

slide14

Spinal Cord External Figure

Conus Medullaris (L1-2)

Spinomedullary Junction

- Foramen Magnum, Pyramidal decussation, C1 ventral root

Enlargements

- Cervical (C4-T1) & Lumbosacral (L1-L4)

Longitudinal Fissures

- anterior median fissure

- anterolateral fissure

- posterior median sulcus

- posterolateral sulcus

slide15

cervical enlargement (C8) thoracic cord (T8)

lumbar enlargement (L3) sacral cord (S1)

slide16

Cervical level

    • Wide flat cord, lots of white matter,
    • ventral horn enlargements.
  • Lumbar level
  • - Round cord, ventral horn enlargements.
  • Sacral level
  • - Small round cord, lateral Horn.
  • Tthoracic level
  • - Notice the pointed tips which stick out
  • between the small dorsal and ventral horns.
  • This extra cell column is called the
  • intermediate horn (AKA: Intermediolateral
  • Cell Column). It is the source of all of the
  • sympathetics in the body & occurs only in
  • the Thoracic sections T 1 - L 2
slide17

Spinal Cord Internal Structure

White Matter

Anterior Funiculus (Anterior White Column)

Posterior Funiculus (Posterior White Column)

Fasciculus Gracilis & Fasciculus Cuneatus

Lateral Funiculus (Lateral White Column)

Gray Matter

Anterior Horn ------------ --- motor

Posterior Horn -------------- sensory

Lateral Horn ----------------- autonomic (sympathetic)

Gray Commissure -------- anterior and posterior

slide18

1. posterior horn

2. anterior horn

3. intermediate zone

(intermediate gray)

4. lateral horn

5. posterior funiculus

6. anterior funiculus

7. lateral funiculus

8. Lissauer's tract

9. anterior median

fissure

10. posterior median

sulcus

11. anterolateral

sulcus

12. posterolateral

sulcus

13. Posterior

intermediate

sulcus

slide19

Spinal Cord Internal Structure

Principles of Cord Organization

1) Longitudinal Arrangement

Fibers (White Matter) ------------- White Column

Cell Groups (Gray Matter) ------- Gray Column

2) Transverse Arrangement

Afferent & Efferent Fibers

Crossing (Commissural and Decussating) Fibers

3) Somatotopical Arrangement

slide22

Lamina of Rexed

Lamina I Posteromarginal Nucleus

Lamina II Substantia Gelatinosa of Rolando

Lamina III

Lamina IV, V, VI ----- Nucleus Proprius

Lamina VII

- Intermediate Gray

- Intermediolateral cell column (ILM)

- Clarke’s column (Nucleus dorsalis)

- Intermediomedial cell column (IMM)

Lamina VIII

Lamina IX ---------- Anterior Horn (Motor) Cell

Lamina X ----------- Gray Commissure

slide23

Lamina I

  • AKA: lamina marginalis
  • or the layer of Waldeyer
  • Receives incoming dorsal root fibers
  • and collateral branches as well
  • Larger neurons contribute axons
  • to Contralateral Spinothalamic Tract
slide24

Lamina II

  • AKA: Substantia Gelatinosa
  • Involved in Pain interpretation
  • Receives incoming input from dorsal
  • rootaxons & descending input from
  • reticular formation of the medulla
  • Efferent axons travel up & down
  • several segments to make contact
  • with other areas of the dorsal horn
slide25

Lamina III

  • Contains larger, less densely packed
  • cells than lamina II
  • Receives primary afferents from
  • dorsal root fibers
  • Neurons considered as a part of
  • nucleus proprius
slide26

Lamina IV

  • Contains a variety of cell types that have
  • more myelin than any other lamina
  • Some tract cells originate here, axons cross
  • the midline and enter the contralateral
  • Spinothalamic Tract, also sends contacts to
  • layers II and III
  • Receives afferents from dorsal roots via
  • the dorsal funiculus
  • At rostral end of spinal cord, laminas I-IV
  • become continuous with the spinal
  • trigeminal nucleus
slide27

Lamina V - VI

  • Origination of tract cells, similar
  • to lamina IV, these tracts cells are
  • also known as the Nucleus Proprius
  • (e.g. spinal thalamic tract or
  • anterolateral system; pain and
  • temperature, some tactile)
  • Receives afferent input from
  • dorsal roots and descending fibers,
  • most importantly Corticospinal
slide28

Lamina V - VI

C7

reticular formation---------------->

Laterally, gray matter at base of dorsal horn mixes with

white matter from lateral funiculus, this region is called

reticular formation. It is noticeable in the cervical region

slide29

Lamina VII

  • The largest region, occupies most of
  • ventral horn &intermediate zone
  • Projects long axons that connect to other
  • gray matter segments of the cord
  • Some columns do not fit into the lamina
  • scheme, and have individual designations:
      • a. Nucleus dorsalis (Clarke)
      • b. Intermediolateral cell column
      • c. Intermediomedial cell column
      • d. Sacral autonomic nucleus
slide30

Lamina VII

  • Nucleus dorsalisof Clark
  • AKAnucleus thoracicus
  • is located medial & ventral
  • to the dorsal horn in T1-L3
  • Composed of large neurons
  • & axons that form the
  • dorsal spinocerebellar tract
  • on the ipsilateral side

T5

slide31

Lamina VII

  • Intermediolateral cell column
  • is located at the lateral portion
  • of the intermediate zone.
  • Responsible for the formation
  • of the lateral horn in T1 - L2
  • Consists of cell bodies of
  • sympathetic preganglionic
  • neurons

T5

slide32

Lamina VII

  • Intermediomedial cell column
  • is located lateral to lamina X.
  • Not seen in all cord sections.
  • Receives primary afferent
  • fibers from dorsal root and
  • has been implicated in
  • visceral reflexes

T5

slide33

Lamina VII

S2

  • Sacral autonomic nucleus
  • is located in the lateral part of
  • lamina VII in S2-S4 segments
  • Consists of preganglionic para-
  • sympathetic neurons
slide34

Lamina VIII

  • Located on the medial aspect of
  • the ventral horn
  • Efferent projections both ipsilaterally
  • and contralaterally to the same and
  • nearby segmental levels to lamina
  • VII & IX
  • Site of termination for descending
  • fibers, including the vestibulospinal
  • and reticulospinal tracts
slide35

Lamina IX

  • Consists of columns of neurons
  • embedded in either lamina VII or VIII
  • Cells include alpha and gamma motor
  • neurons, which axons exit via the
  • ventral roots and innervate striated
  • muscle. Smaller neurons contribute
  • axons to the ventral fasciculus proprius
  • Four columns of motor neurons can
  • be identified within this lamina;
  • ventromedial, ventrolateral, dorsolateral
  • & central each has characteristic
  • dendritic features
slide36

Lamina IX

Ventral gray columns in lamina IX

have somatotopic arrangement:

- Medial areas innervate the

axial musculature

- Lateral areas innervate the

limbs muscles

slide37

PHRENIC NUCLEUS

The phrenic nucleus is located in the ventromedial area of the

ventral horn in C2-C5 segments. It receives bilateral innervation from the solitary nucleus of the medullary region, via solitary tract. This nucleus is responsible for the innervation of the diaphragm

SPINAL ACCESSORY NUCLEUS

The spinal accessory nucleus (cranial nerve XI) is located in the

lateral area of vental horn in C1-C5 segments. Corticospinal tract innervates this nucleus bilaterally. This nucleus is also responsible for the innervation of the trapezius & sternocleidomastoid muscles (ipsilaterally)

slide38

Lamina IX

  • Located ventrolaterally in
  • S1-S2 spinal segments
  • Supplies muscles of the
  • pelvic floor, including striated
  • muscle sphincters for urinary
  • and fecal continence

Nucleus of Onuf

S2

slide39

Lamina X

  • Surrounds the central canal, and
  • includes the ventral gray commissure
  • Contains relatively small neurons,
  • radial neuroglia cells & decussating
  • axons
  • Some dorsal root afferents terminate
  • here
slide40

Fasiculus Proprius

  • Ascending and descending association fiber systems of the
  • spinal cord which lie deep in the anterior, lateral & posterior
  • funiculi adjacent to the gray matter.
  • Fasciculi proprii aka Flechsig's fasciculi or Ground bundles
  • consist of: anterior, lateralis & intersegmental fasciculi
slide41

Dorsal Roots

  • Each dorsal root divides
  • into 6 - 8 rootlets
  • Each rootlet can be divided into
  • lateral & medial division
  • Lateral division carries
  • information related to pain
  • & temperature
  • Medial division carries
  • information related to tactile
  • discrimination & vibration
slide42

Dorsal Roots

  • Lateral divisionaxons enter
  • dorsolateral tract of Lissauer,
  • and then divide into ascending
  • & descending branches, each
  • terminate in the dorsal horn
  • Most terminate at same
  • level & some fibers may
  • travel up or down the cord
  • up to four levels
slide43

Dorsal Roots

  • Medial division axons enter the
  • white matter & then divide into
  • ascending & descending branches
  • Descending branches are
  • organized into two bundles,
  • the Septomarginalis Fasiculus
  • and the Interfascicular Fasiculus
  • All descending branchesterminate
  • in the dorsal horn
slide44

Dorsal Roots

  • Ascending branches of the
  • medial divisionenter the
  • dorsal funiculus & terminate
  • in gracile & cuneate nuclei
  • in the medulla
slide45

Ventral Horn

  • Lamina IX contains two types
  • of motor neurons, alpha and
  • gamma
  • Alpha motor neurons innervate
  • extrafusal fibers of striated
  • skeletal muscles
  • Gamma motor neurons innervate
  • intrafusal fibers of neuromuscular
  • spindles
  • Both types receive inputs from
  • interneurons, including the
  • inhibitory Renshaw cell
slide47

Tracts of the Spinal Cord

Fasciculus Gracilis

Fasciculus Cuneatus

Tractus spinocerebellaris dorsalis

Tractus corticospinalis lateralis

Tractus spinothalamicus lateralis

Tractus spinocerebellaris ventralis

Tractus rubrospinalis

Tractus spinotectalis

Tractus corticospinalis anterior

Tractus olivospinalis

Tractus spinoolivaris

Tractus tectospinalis

Tractus reticulospinalis

Tractus vestibulospinalis

Tractus spinothalamicus anterior

Raphe-spinal & Hypothalamospinal fibers

16

slide48

Spinal Cord Tracts

Ascending Tracts

Modality: Touch, Pain, Temperature, Kinesthesia

Receptor: Exteroceptor, Interoceptor, Proprioceptor

Primary Neuron: Dorsal Root Ganglion (Spinal Ganglion)

Secondary Neuron: Spinal Cord or Brain Stem

Tertiary Neuron: Thalamus (Ventrobasal Nuclear Complex)

Termination: Cerebral Cortex, Cerebellar Cortex, or

Brain Stem

slide49

Spinal Cord Tracts

Ascending Tracts

Posterior White Column-Medial Lemniscal Pathway

Spinothalamic Tract

Spinoreticular or Spinoreticulothalamic Tract

Spinocerebellar Tract

Spinomedullothalamic Tract

Cervicothalamic or Spinocervicothalamic Tract

Spino-olivary Tract

Spinotectal Tract

slide51

Spinal Cord Ascending Tracts

Posterior White Column-Medial Lemniscal Pathway

Modality: Discriminative Touch Sensation (include Vibration) and

Conscious Proprioception (Position Sensation, Kinesthesia)

Receptor: Most receptors except free nerve endings

Ist Neuron: Dorsal Root Ganglion (Spinal Ganglion)

Posterior Root - Posterior White Column

2nd Neuron: Dorsal Column Nuclei(Nucleus Gracilis et Cuneatus)

Internal Arcuate Fiber - Lemniscal Decussation

- Medial Lemniscus

3rd Neuron: Thalamus (VPLc)

Internal Capsule ----- Corona Radiata

Termination: Primary Somesthetic Area (S I)

slide52

medial lemniscus

lemniscal decussation

internal arcuate fiber

posterior white column

posterior root

Posterior White Column -

Medial Lemniscal Pathway

- ipsilateralloss of discriminative touch

sensation and conscious proprioception

belowthe level of lesion

slide53

Spinal Cord Ascending Tracts

Spinothalamic Tract

Modality: Pain & Temperature Sensation, Light Touch

Receptor: Free Nerve Ending

Ist Neuron: Dorsal Root Ganglion (Spinal Ganglion)

Posterior Root

2nd Neuron: Dorsal Horn (Lamina IV, V, VI)

Spinothalamic Tract - (Spinal Lemniscus)

3rd Neuron: Thalamus (VPLc, CL & POm)

Internal Capsule ----- Corona Radiata

Termination: Primary Somesthetic Area (S I) &

Diffuse Widespread Cortical Region

slide54

spinothalamic

tract

anterior white

commissure

posterior root

decussation

Spinothalamic Tract

- contralateral loss of pain and temperature

sensation below the level of lesion

slide55

NeoSTTPaleoSTT

Primary Motor

Area (M I)

VPLc (ventrobasal

nuclear complex)

(spinal lemniscus)

spinothalamic

tract

Widespread

cortical region

CL (intralaminar

thalamic nuclei)

reticulothalamic

pathways

spinoreticular

tract

thalamus

reticular

formation

Spinothalamic Tract

& Spinoreticular Tract

slide56

Comparison of Fast and Slow Pain------ Spinothalamic Tract

Fast PainSlow Pain

Sharp, pricking Dull, burning

Group III (A) fiber Group IV (C) fiber

Short latency Slower onset

Well localized Diffuse

Short duration Long duration

Less emotional Emotional, autonomic response

Not blocked by morphine Blocked by morphine

Neospinothalamic Tract Paleospinothalamic Tract

slide57

Spinal Cord Ascending Tracts

Spinocerebellar Tract

Modality: Unconscious Proprioception

Receptor: Muscle spindle, Golgi tendon organ

Ist Neuron: Dorsal Root Ganglion (Spinal Ganglion)

Posterior Root , [Posterior Column]

2nd Neuron: 1. Clarke’s column (Lamina VII)

Posterior Spinocerebellar Tract

2. Accessory Cuneate Nucleus

Cuneocerebellar Tract

3. Posterior Horn

Anterior Spinocerebellar Tract

Termination: Cerebellar Cortex

slide58

Anterior SCbllT

(superior

cerebellar

peduncle)

anterior

spinocerebellar

tract

anterior white

commissure

posterior root

Posterior SCbllT

Inferior

cerebellar

peduncle

cuneocerebellar

tract

(upper body)

posterior

white column

posterior root

Inferior cerebellar

peduncle

posterior

spinocerebellar

tract

Clarke’s

column

posterior

white column

posterior root

Spinocerebellar Tract

slide60

Spinal Cord Descending Tracts

Corticospinal Tract

Origin: Cerebral Cortex

Brodmann Area 4 (Primary Motor Area, M I)

Brodmann Area 6 (Premotor Area, PM )

Brodmann Area 3,1,2 (Primary Somesthetic Area, S I)

Brodmann Area 5 (Anterior Portion of Sup. Parietal Lobule)

Corona Radiata

lnternal Capsule, Posterior Limb

Crus Cerebri, Middle Portion

Longitudinal Pontine Fiber

Pyramid - pyramidal decussation

Corticospinal Tracts:

- Lateral (crossed) - 85%

- Anterior (Not crossed) - 15%

Termination: Spinal Gray (Rexed IV-IX)

slide62

Corona Radiata

lnternal Capsule, Posterior Limb

Crus Cerebri, Middle Portion

Longitudinal Pontine Fiber

Pyramid

Pyramidal Decussation

Corticospinal Tract

- Lateral and Anterior

CR

IC

LPF

Corticospinal Tract

Pyr

LCST

PD

- ipsilateralUMN syndrome

at the level of lesion

ACST

slide63

Spinal Cord Descending Tracts

Descending Tracts from Brain Stem

Dorsolateral (Motor) Pathway

Rubrospinal Tract

Ventromedial (Motor) Pathway

Tectospinal Tract

Vestibulospinal Tract

MLF (Medial Longitudinal Fasciculus)

- interstitiospinal tract

Sensory Modulation pathways

Raphespinal & Cerulospinal Pathways

Descending Autonomic Pathways

slide64

Spinal Cord

Tracts

ventromedial

pathway

dorsolateral

pathway

Descending

Tracts

from

Brain Stem

slide65

SOMATIC MOTOR SYSTEM

upper motor neuron

UMN

Brain Stem

Descending

Pathway

Rubrospinal Tract

Tectospinal Tract

Vestibulospinal Tract

MLF

Reticulospinal Tract

Final Common Pathway

VOLUNTARY

CONTROL

lower motor neuron

LMN

Pyramidal Tract

AUTOMATIC CONTROL

REFLEX

EFFECTORS

skeletal muscle

slide66

Spinal Cord Syndrome

Location of

Symptoms in

Spinal Disease

ipsilateral to lesion contralateralto lesion

slide67

Upper Motor Neuron (UMN) vs. Lower Motor Neuron (LMN) Syndrome

UMN syndromeLMN Syndrome

Type of Paralysis Spastic Paresis Flaccid Paralysis

Atrophy No (Disuse) Atrophy Severe Atrophy

Deep Tendon Reflex Increase Absent DTR

Pathological Reflex Positive Babinski Sign Absent

Superficial Reflex AbsentPresent

Fasciculation and Absent Could be

Fibrillation Present

slide68

Spinal Cord Syndrome

  • Predominantly Motor Syndromes
  • Poliomyelitis (Infantile Paralysis)
  • - viral infection of lower motor neuron
  • - LMN syndrome at the level of lesion
  • Amyotrophic Lateral Sclerosis (ALS)
  • - combined LMN and UMN lesion
  • - LMN syndrome at the level of lesion
  • - UMN syndrome below the level of lesion
  • - Lou Gehrig’s disease
slide69

Spinal Cord Syndrome

1. corticospinal

tract

2. lower motor

neuron (LMN)

Amyotrophic Lateral Sclerosis

slide70

Spinal Cord

Syndrome

Amyotrophic

Lateral Sclerosis

(ALS)

Lou Gherig’s

Disease

Lou "The Iron Horse" Gehrig (1903-41)

3.40, 2131(1925-39), 23 GSH, 147 RBI avg.

slide71

Spinal Cord

Syndrome

Amyotrophic

Lateral Sclerosis

(ALS)

Lou Gherig’s

Disease

Stephen Haking (1946- )

British Physicist, A Brief History of Time

slide72

Spinal Cord Syndrome

  • Predominantly Sensory Syndromes
  • Herpes Zoster
  • - inflammatory reactions of spinal ganglion
  • - severe pain on the dermatomes of affected ganglion
  • Tabes Dorsalis
  • - common variety of neurosyphilis
  • - posterior column and spinal posterior root lesion
  • - loss of discriminative touch sensation and conscious
  • proprioception below the level of lesion
  • - posterior column ataxia
  • - lancinating pain (a stabbing or piercing sensation)
  • - loss of deep tendon reflex (DTR)
slide73

Herpes Zoster (Shingles)

  • varicella-zoster virus
  • reactivation from
  • the dorsal root ganglia
  • unilateral vesicular
  • eruption within
  • a dermatome
  • T3 to L3 dermatome
  • lesions are frequent
  • zoster ophtahalmicus
  • (ophthalmic division
  • of trigeminal n., V1)
  • Ramsey-Hunt syndrome
  • (sensory br. of VII)
  • acyclovir, antiviral agent
slide74

Spinal Cord Syndrome

Sub-Acute Combined Degeneration

(Combined System Disease)

Lesion

- posterior white column

- corticospinal tract (UMN)

Symptom

- loss of discriminative touch sensation and conscious

proprioception below the level of lesion

- ipsilateral UMN syndrome below the level of lesion

slide75

Spinal Cord Syndrome

1. corticospinal

tract

2. posterior

white column

Sub-Acute Combined Degeneration

slide76

Spinal Cord Syndrome

Syringomyelia, Hematomyelia

Lesion

- central canal of spinal cord

- gradually extended to peripheral part of the cord

Symptom

- initial symptom is bilateral loss of pain

(compression of anterior white commissure)

- variety of symptoms appear

according to the lesion extended from central canal

slide77

Spinal Cord Syndrome

Syringomyelia - Initial Symptoms

slide79

Spinal Cord Syndrome

Brown-Sequard syndrome

(spinal cord hemisection)

Major Symptoms

1. ipsilateral UMN syndromebelow the level of lesion

2. ipsilateral LMN syndromeat the level of lesion

3. ipsilateral loss of discriminative touch sensation and

conscious proprioceptionbelow the level of lesion

(posterior white column lesion)

4. contralateral loss of pain and temperature sensation

below the level of lesion (spinothalamic tract lesion)

slide80

Spinal Cord Syndrome

Brown-Sequard Syndrome (Spinal Cord Hemisection)