The Spinal Cord

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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
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Spinal Cord
- Comparable to Input-Output (IO) System of
the Computer - Spinal Nerve (C8, T12, L5, S5,
Cx1) - Segmental Structure of Neural Tube Origin
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Spinal segment C8, T12, L5, S5,
Cx1 Anterior (Ventral) Root Posterior (Dorsal)
Root Dorsal Root (Spinal) Ganglion Root -
Rootlets
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Conus Medullaris (L1-2) Cauda Equina Anterior
median fissure Anterolateral fissure
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Posterior median sulcus Posterolateral
sulcus Posterior intermediate sulcus
Fasciculus cuneatus Fasciculus
gracilis
Posterior surface of the spinal cord
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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
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• Meninges of
• the spinal cord
• Dura mater
• Arachnoid membrane
• Pia mater

Denticulate ligament - specialization of the
pia mater - landmark for cordotomy
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Meninges of the spinal cord
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Meninges of the spinal cord
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Lumbar Puncture lumbar (terminal) cistern
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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
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5. Adamkiwicz artery
anterior spinal artery segmental arteries
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Spinal Cord
External Figure
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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
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cervical enlargement (C8) thoracic cord
(T8)
lumbar enlargement (L3) sacral cord
(S1)
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• 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

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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 ----------------- a
utonomic (sympathetic) Gray
Commissure -------- anterior and posterior
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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
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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
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Columnar arrangement Somatotopical
arrangement
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Lamina of Rexed

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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) - Clarkes
column (Nucleus dorsalis) - Intermediomedial
cell column (IMM) Lamina VIII Lamina IX
---------- Anterior Horn (Motor) Cell Lamina X
----------- Gray Commissure
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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

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Lamina II

• AKA Substantia Gelatinosa
• Involved in Pain interpretation
• Receives incoming input from dorsal
• root axons 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

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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

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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

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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

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Lamina V - VI
C7
reticular formation ----------------gt
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
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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

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Lamina VII

• Nucleus dorsalis of Clark
• AKA nucleus 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
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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
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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
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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

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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

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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

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Lamina IX
Ventral gray columns in lamina IX have
somatotopic arrangement - Medial areas
innervate the axial musculature -
Lateral areas innervate the limbs muscles
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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)
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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
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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

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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

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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

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Dorsal Roots

• Lateral division axons 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

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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 branches terminate
• in the dorsal horn

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Dorsal Roots

• Ascending branches of the
• medial division enter the
• dorsal funiculus terminate
• in gracile cuneate nuclei
• in the medulla

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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

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Spinal Cord
Tracts

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Tracts of the Spinal Cord

1. Fasciculus Gracilis
2. Fasciculus Cuneatus
3. Tractus spinocerebellaris dorsalis
4. Tractus corticospinalis lateralis
5. Tractus spinothalamicus lateralis
6. Tractus spinocerebellaris ventralis
7. Tractus rubrospinalis
8. Tractus spinotectalis
9. Tractus corticospinalis anterior
10. Tractus olivospinalis
11. Tractus spinoolivaris
12. Tractus tectospinalis
13. Tractus reticulospinalis
14. Tractus vestibulospinalis
15. Tractus spinothalamicus anterior
16. Raphe-spinal Hypothalamospinal fibers

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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
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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

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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)
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medial lemniscus lemniscal decussation internal
arcuate fiber posterior white column posterior
root
Posterior White Column - Medial Lemniscal Pathway
- ipsilateral loss of discriminative touch
sensation and conscious proprioception
below the level of lesion
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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
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spinothalamic tract anterior white commissure
posterior root
decussation
Spinothalamic Tract
- contralateral loss of pain and temperature
sensation below the level of lesion
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NeoSTT PaleoSTT
Widespread cortical region CL (intralaminar
thalamic nuclei) reticulothalamic
pathways spinoreticular tract
Primary Motor Area (M I) VPLc (ventrobasal
nuclear complex) (spinal lemniscus) spinothalam
ic tract
thalamus
reticular formation
Spinothalamic Tract Spinoreticular Tract
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Comparison of Fast and Slow Pain ------
Spinothalamic Tract
Fast Pain Slow 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
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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.
Clarkes column (Lamina VII)
Posterior Spinocerebellar
Tract 2. Accessory
Cuneate Nucleus
Cuneocerebellar Tract
3. Posterior Horn
Anterior Spinocerebellar
Tract Termination Cerebellar Cortex
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Posterior SCbllT Inferior cerebellar
peduncle cuneocerebellar tract (upper
body) posterior white column posterior root
Anterior SCbllT (superior cerebellar
peduncle) anterior spinocerebellar
tract anterior white commissure posterior
root
Inferior cerebellar peduncle posterior
spinocerebellar tract Clarkes
column posterior white column posterior root
Spinocerebellar Tract
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Spinocerebellar Tract
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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)
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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
- ipsilateral UMN syndrome at the level
of lesion
ACST
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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
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Spinal Cord Tracts

ventromedial pathway
dorsolateral pathway
Descending Tracts from Brain Stem
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SOMATIC MOTOR SYSTEM
upper motor neuron UMN
Brain Stem Descending Pathway
Rubrospinal Tract Tectospinal Tract Vestibulospina
l Tract MLF Reticulospinal Tract
Final Common Pathway
VOLUNTARY CONTROL
lower motor neuron
LMN
Pyramidal Tract
AUTOMATIC CONTROL
REFLEX
EFFECTORS skeletal muscle
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Spinal Cord
Syndrome
Location of Symptoms in Spinal Disease
ipsilateral to lesion contralateral to
lesion
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Upper Motor Neuron (UMN) vs. Lower Motor Neuron
(LMN) Syndrome
UMN syndrome LMN 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 Absent
Present Fasciculation and Absent
Could be Fibrillation

Present
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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 Gehrigs disease

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Spinal Cord
Syndrome
1. corticospinal tract
2. lower motor neuron (LMN)
Amyotrophic Lateral
Sclerosis
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Spinal Cord Syndrome Amyotrophic Lateral
Sclerosis (ALS) Lou Gherigs Disease
Lou "The Iron Horse" Gehrig (1903-41) 3.40,
2131(1925-39), 23 GSH, 147 RBI avg.
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Spinal Cord Syndrome Amyotrophic Lateral
Sclerosis (ALS) Lou Gherigs Disease
Stephen Haking (1946- ) British Physicist, A
Brief History of Time
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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)

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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

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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
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Spinal Cord
Syndrome
1. corticospinal tract
2. posterior white column
Sub-Acute Combined
Degeneration
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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
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Spinal Cord
Syndrome
Syringomyelia - Initial
Symptoms
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Spinal Cord
Syndrome
Brown-Sequard syndrome (spinal
cord hemisection) Major
Symptoms 1. ipsilateral UMN syndrome below
the level of lesion 2. ipsilateral LMN
syndrome at the level of lesion 3.
ipsilateral loss of discriminative touch
sensation and conscious
proprioception below the level of lesion
(posterior white column lesion) 4.
contralateral loss of pain and temperature
sensation below the level of lesion
(spinothalamic tract lesion)
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Spinal Cord
Syndrome
Brown-Sequard Syndrome (Spinal Cord
Hemisection)
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