3. Objectives
After completing the session we will be able to
• Describe vertebral column anatomy
• Explain spinal cord anatomy
• Describe blood supply to spinal cord
4. The Vertebral Column
• central bony pillar of the
body.
• It supports
• transmits body weight
• Within its cavity lie the
spinal cord, the roots of
the spinal nerves, and the
covering meninges
• 33 vertebra (7 cervical, 12
thoracic, 5 lumbar, 5
sacral(fused) 4 coccygeal
(the lower 3 are commonly
fused))
5. Composition of the Vertebral Column
• typical vertebra consists of a
rounded body anteriorly and a
vertebral arch posteriorly.
• The vertebral arch consists of a
pair of cylindrical pedicles,
which form the sides of the
arch, and a pair of flattened
laminae, which complete the
arch posteriorly.
• The vertebral arch gives rise to
seven processes: one spinous,
two transverse, and four
articular
6. Characteristics of a Typical Cervical Vertebra
• The transverse processes
possess a foramen
transversarium for the
passage of the vertebral
artery and veins.
• The spines are small and
bifid.
• The body is small and
broad from side to side.
• The vertebral foramen is
large and triangular
7. Cont.
• Atlantoaxial Spine and
Craniospinal Articulation
• The atlas (C1) is a ring with
prominent lateral masses
bilaterally supporting the
head’s weight and
permitting head flexion
and extension via its
superior concave, medially
directed articulations with
the occipital condyles
8. Cont.
• The axis (C2) provides
a majority of the
neck’s axial rotation
via its odontoid
process (dens), which
projects superiorly
from its body.
• This articulation is
supported by the
transverse ligament
across the ring of the
9. Thoracic vertebra
• characterized by
substantial stability by its
costal articulations.
• Each rib articulates with
two vertebral bodies each
of which in turn harbors
superiorly and inferiorly
oriented costal demifacets
11. Sacrum
• is a triangular, anteriorly
concave bone bridging—
and sharing loads
between—the spine and
the pelvis through its
complex articulations
• Composed of five
vertebrae by early
adulthood
12. Intervertebral Discs
• extend from C2 to the
sacrum (C1 has no vertebral
body).
• The discs are responsible for
one quarter of the length of
the vertebral column.
• They are thickest in the
cervical and lumbar regions,
where the movements of
the vertebral column are
greatest.
14. Spinal cord
• In the vertebral column,
– Roughly cylindrical in shape
– 45cm adult male
43 cm adult female
– foramen magnum continuous
terminates at
– lower border of L1 in adults
– upper border of L3 in children
tapers inferiorly into
conus medullaris
cauda equina
15. Spinal cord
• Surrounded by meninges( dura, arachnoid
and pia mater)
– CSF found in subarachnoid space
• Denticulate ligament (The dentate ligament
separates dorsal from ventral nerve roots in
the spinal nerves)
• Filum terminale
• Has 31 paired spinal nerves
• Enlargements
19. Structure of spinal cord
• Gray matter
• White matter
• Anterior median fissure
• Posterior median sulcus
• Posterolateral sulcus
• Anterolateral sulcus
20. Gray matter
• H shaped pillar with anterior and posterior columns or
horns
• Thin commissure with small central canal
small lateral gray column in thoracic and upper lumbar
segments
21. Gray commissure and central canal
• Grey commissure - Connect anterior and posterior gray horn
in each half
• Central canal - located in the center of grey commissure
– Open to fourth ventricle superiorly
– Terminate within root of Filum Terminale
– It is filled with CSF
23. Posterior gray column
Four nerve cell groups
1. Substantia gelatinosa
Lamina ll
• at apex of post gray column,
throughout Spinal cord.
Pain, temperature, touch
24. Cont.
2. Nucleus proprius
Lamina lll & lV
• anterior to substantia gelatinosa
throughout the spinal cord
receives fibers from posterior white
column associated with position &
proprioception
28. Anterior gray column
Lamina VIII & IX
Cell bodies of somatic motor neuron
• Medial group- skeletal muscles of neck and trunk muscles
• Central group-(C3- C5) phrenic nucleus- diaphragm
(C1- C5) accessory nucleus
sternocleidomastoid and trapezius
• Lateral group-(cervical & lumbosacral) skeletal muscles of the
limb
29. Types of white matter in CNS
• Association fibers – U shaped, connect the
gyrus to another gyrus in the same
hemisphere
• Commissural fibers- connect the two
hemispheres of the brain ----corpus callosum
In spinal cord- to cross over
• Projection fibers- run longitudinally
30. White matter
• Surrounds the gray matter in SC
• Composed of axons, neuroglia and
blood vessels.
High portion of myelinated nerve
fibers
• Dorsal column- B/n posterior
median sulcus & posterolateral
sulcus
• Anterior column- B/n
anterolateral sulcus &anterior
median fissure
• Lateral column- B/n posterolateral
sulcus & anterolateral sulcus
35. 1.Lateral spinothalamic tract
• Pain and temperature
• Transmitted through delta A
& C fibers
• First order neuron
central process- tip of dorsal gray
horn (substantia gelatinosa)
• Second order neuron
- Dorsal horn cross to
opposite side
- ascend in contralateral VC
- ends in VPL of thalamus
• Third order neuron
- In VPL nucleus of thalamus
- projets to cerbral cortex
(area3,1 ,2)
Dorsolateral tarct of lissaure
36. 2. Anterior spinothalamic tract
Light touch and pressure
free nerve ending
(Merkel’s tactile disks)
• First order neuron
- DRG all level
• Second order neuron
- Dorsal horn cross to
opposite side
- ascend in contralateral VC
- ends in VPL of thalamus
• Third order neuron
- In VPL nucleus of thalamus
- projets to cerbral cortex
(area3,1 ,2)
37. 3. Posterior white column
• Discriminative touch,
vibration, position
• Decussating at the level
of medulla
• Fasciculus gracilis
– Contains fibers from sacral,
lumbar & lower 6
thoracic(T7-T12) nerves
• Fasciculus cuneatus
– Contain fibers from upper 6
thoracic(T1-T6) & all cervical
nerves
38. 4. Anterior and Posterior spinocerebellar
tract
• Unconscious proprioceptive
information to cerebellum
• Input from muscles spindles &
pressure receptors
Posterior spinocerebellar- C8-
L2
*Nucleus dorsalis of clarke
Anterior spinocerebellar-
lumbosacral
• 5. Cuneocerebellar tract
39. Cont.
6. Spinotectal tract
• Spinovisual responses
• Terminates at superior midbrain
– brings movements of eyes &
head towards source of stimulus
7. Spinoreticular tract
-Uncrossed fibers, synapse
with neurons of reticular
formation
(role in influencing level of
consciousness)
40. Cont.
8. Visceral sensory tract
– Carry pain &stretch from viscera(thorax and
abdomen)
– 1st
and 2nd
order neuron synapse in spinal cord at
visceral afferent nucleus (posterior gray column)
– 2nd
and 3rd
order neurons synapse at thalamus and
terminate in cerebral cortex
42. 42
The motor pathways are divided into two groups
1. Direct pathways (voluntary
motion pathways)
Pyramidal /corticospinal
2.Indirect pathways (postural
pathways), essentially all others
Extrapyramidal pathways
Rubrospinal
Tectospinal
Vestibulospinal
Olivospinal
Reticulospinal
Descending autonomic fibers
43. 43
voluntary, discrete, skilled
movements esp.distal parts of limbs
Origin: motor and sensory cortices
At Pyramid of medulla oblongata
1. 75-90% of the fibers decussate lateral
corticospinal tract
2. The rest form anterior corticospinal
tract,decussate at segmental levels (0–
3% do not)before termination
Lesions Weakness
Corticospinal Tracts
46. 46
Blood supply of spinal cord
Two sources
– vertebral arteries
– segmental spinal arteries
• Vertebral artery- gives 3
small arteries
– Two posterior spinal
arteries & one anterior
spinal artery
47. Cont’d
• Segmental spinal arteries-
– Feed into spinal cord at different level
– Branch of posterior intercostal arteries , deep cervical ,
lumbar arteries and lateral sacral artery
– Gives rise to anterior and posterior radicular arteries that
accompany anterior and posterior nerve roots of spinal
cord
– Enter vertebral canal through intervertebral foramen
Segmental medullary arteries
Arteria medullaris magna
48. Venous drainage of spinal cord
• Similar distribution
• Longitudinal vv. (anterior , posterior spinal), anterolateral vv,
posterolateralvv --------radicular veins-------internal vertebral
venous plexus (epidural space) ------- external vertebral
venous plexus------- Lumbar, Deep cervial, Azygous
50. Complete cord transection syndrome
• Devastating injury, trauma …
• Complete loss of motor and sensory function
• UMN & LMN
• Conus medullaris transection
• Cauda equina syndrome
51. 51
Anterior cord syndrome
Causes:
o Cord contusion by
vertebral compression
o Injury to Ant. Spinal artery
Ischemic damage to CST &
STT.
o Herniated IVD.
C/F
Motor deficit
Bilateral Pain, temperature & light touch
loss.
Position, vibration, 2-point
discrimination- preserved
53. Posterior cord syndrome
• Rare
• Hyper flexion, posterior spinal artery occlusion
• Tabes dorsalis – syphilitic degeneration of the
posterior columns and posterior nerve roots
– Loss of proprioception
– Becomes ataxic particularly when closing his eyes
because loss of sense of position
#4:Normal spinal alignment is characterized by cervical lordosis, thoracic kyphosis, and lumbar lordosis, which together result in sagittal balance
In addition to the facet joint capsule, the posterior ligamentous complex stabilizing the posterior bony elements of the vertebral column includes the ligamentum flavum joining laminae, the supraspinatus and interspinous ligaments joining spinous processes, and the intertransverse ligaments, which join adjacent transverse processes
#11:(via facet articulations facing medially and posteriorly),
#15:21 pairs of toothed ligaments that stand out from pia mater on each side of the spinal cord to be attached to the dura.
#37:Synapse with 2nd order neuron at medulla obolongata in nuclei cuneatus
2nd order neuron cross midline at medulla & synapse with 3rd order neuron at thalamus
