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)
- Segmental Structure of Neural Tube Origin
Spinal segment
C8, T12, L5, S5, Cx1
Anterior (Ventral) Root
Posterior (Dorsal) Root
Dorsal Root (Spinal) Ganglion
Root - Rootlets
Conus Medullaris (L1-2)
Cauda Equina
Anterior median fissure
Anterolateral fissure
Posterior
median sulcus
Posterolateral
sulcus
Posterior
intermediate
sulcus
Fasciculus
cuneatus
Fasciculus
gracilis
Posterior surface of the spinal cord
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
Meninges of
the spinal cord
• Dura mater
• Arachnoid membrane
• Pia mater
Denticulate ligament
- specialization of the pia mater
- landmark for cordotomy
Meninges of the spinal cord
Meninges of the spinal cord
Lumbar Puncture – lumbar (terminal) cistern
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
5. Adamkiwicz artery
anterior spinal artery
segmental arteries
Spinal Cord
External Figure
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
cervical enlargement (C8)
lumbar enlargement (L3)
thoracic cord (T8)
sacral cord (S1)
• 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
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 --------------Posterior Horn -------------Lateral Horn ----------------Gray Commissure --------
motor
sensory
autonomic (sympathetic)
anterior and posterior
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
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
Columnar arrangement
Somatotopical arrangement
Lamina of Rexed
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
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
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
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
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
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
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
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
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
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
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
Lamina VII
S2
• Sacral autonomic nucleus
is located in the lateral part of
lamina VII in S2-S4 segments
• Consists of preganglionic parasympathetic neurons
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
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
Lamina IX
Ventral gray columns in lamina IX
have somatotopic arrangement:
- Medial areas innervate the
axial musculature
- Lateral areas innervate the
limbs muscles
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)
Lamina IX
Nucleus of Onuf
• Located ventrolaterally in
S1-S2 spinal segments
• Supplies muscles of the
pelvic floor, including striated
muscle sphincters for urinary
and fecal continence
S2
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
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
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
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
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
Dorsal Roots
• Ascending branches of the
medial division enter the
dorsal funiculus & terminate
in gracile & cuneate nuclei
in the medulla
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
Spinal Cord
Tracts
Tracts of the Spinal Cord
16
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
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
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
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
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)
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
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
spinothalamic
tract
decussation
anterior white
commissure
posterior root
Spinothalamic Tract
- contralateral loss of pain and temperature
sensation below the level of lesion
NeoSTT
Primary Motor
Area (M I)
PaleoSTT
Widespread
cortical region
VPLc (ventrobasal CL (intralaminar
nuclear complex) thalamic nuclei)
thalamus
(spinal lemniscus) reticulothalamic
pathways
spinothalamic
tract
spinoreticular
tract
Spinothalamic Tract
& Spinoreticular Tract
reticular
formation
Comparison of Fast and Slow Pain ------ Spinothalamic Tract
Fast Pain
Sharp, pricking
Group III (A) fiber
Short latency
Well localized
Short duration
Less emotional
Not blocked by morphine
Neospinothalamic Tract
Slow Pain
Dull, burning
Group IV (C) fiber
Slower onset
Diffuse
Long duration
Emotional, autonomic response
Blocked by morphine
Paleospinothalamic Tract
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
Anterior SCbllT
Posterior SCbllT
(superior
cerebellar
peduncle)
Inferior
cerebellar
peduncle
anterior
spinocerebellar
tract
cuneocerebellar
tract
(upper body)
posterior
spinocerebellar
tract
anterior white
commissure
posterior
white column
Clarke’s
column
posterior root
posterior root
Spinocerebellar Tract
Inferior cerebellar
peduncle
posterior
white column
posterior root
Spinocerebellar Tract
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)
Corona Radiata
lnternal Capsule, Posterior Limb
Crus Cerebri, Middle Portion
Longitudinal Pontine Fiber
Pyramid
CR
Pyramidal Decussation
Corticospinal Tract
IC
- Lateral and Anterior
LPF
Corticospinal Tract
Pyr
PD
- ipsilateral UMN syndrome
at the level of lesion
ACST
LCST
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
Spinal Cord
Tracts
Descending
Tracts
from
Brain Stem
ventromedial
pathway
dorsolateral
pathway
SOMATIC MOTOR SYSTEM
upper motor neuron
UMN
VOLUNTARY
CONTROL
Brain Stem
Descending
Pathway
Rubrospinal Tract
Tectospinal Tract
Vestibulospinal Tract
MLF
Reticulospinal Tract
Final Common Pathway
lower motor neuron
LMN
Pyramidal Tract
AUTOMATIC CONTROL
REFLEX
EFFECTORS
skeletal muscle
Spinal Cord
Syndrome
Location of
Symptoms in
Spinal Disease
ipsilateral to lesion
contralateral to lesion
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
Fibrillation
Absent
Could be
Present
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
Spinal Cord
Syndrome
1. corticospinal
tract
2. lower motor
neuron (LMN)
Amyotrophic Lateral Sclerosis
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.
Spinal Cord
Syndrome
Amyotrophic
Lateral Sclerosis
(ALS)
Lou Gherig’s
Disease
Stephen Haking (1946- )
British Physicist, A Brief History of Time
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)
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
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
Spinal Cord
1. corticospinal
tract
Syndrome
2. posterior
white column
Sub-Acute Combined Degeneration
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
Spinal Cord
Syndrome
Syringomyelia - Initial Symptoms
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)
Spinal Cord
Syndrome
3
3'
1
3'
1
3
1
1'
4'
2
2'
5'
4
4
5
1'
3
3
1
Brown-Sequard Syndrome (Spinal Cord Hemisection)