The document summarizes the contents of the vertebral canal, including the spinal cord, meninges (dura mater, arachnoid mater, pia mater), blood supply, and applied anatomy of epidural anesthesia and lumbar puncture. Key structures mentioned include the spinal cord terminating at L1-L3, the cauda equina formed by nerve roots, the subarachnoid space containing cerebrospinal fluid, and the valveless vertebral venous system that allows blood flow in either direction.
8. Vertebral Column
Central bony pillar of the body.
Supports the skull, pectoral girdle, upper
limbs and the thoracic cage.
Within its cavity lie the spinal cord, the roots
of the spinal nerves, the covering-meninges.
Composed of 33 vertebrae: 7 cervical, 12
thoracic, 5 lumbar, 5 sacral, 4 coccygeal.
It is a flexible structure made up of
fibrocartilage called intervertebral discs.
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9. VERTEBRAL CANAL
The vertebral
canal is formed by
placing the
vertebra in a
sequence, that
their vertebral
foraminae are lie
one below the
other forming
continuous canal
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10. The vertebral canal
The vertebral canal is bounded
anteriorly by the vertebral bodies and
the intervertebral discs, each
covered by the posterior longitudinal
ligament, which is continuous from
the back of the body of the axis to
the sacrum.
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11. The vertebral canal
Posteriorly it is bounded
by the laminae,
ligamenta flava and the
arch of the vertebra.
The vertebral canal is
usually larger in the
cervical and lumbar
regions.
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12. CONTENTS OF VERTEBRAL CANAL
The contents –from outwards;
1.epidural or extra dural space
2.thick dura mater or pachymenix
3.subdural capillary space
4.delicate arachnoid mater
5.wide subarachnoid space containing CSF
6.firm pia mater .The Arachnoid and Piamater together-leptomeninges
7.spinal cord and the cauda equina
8.Blood supply [arteries and lodges, valveless, dangerous venous plexus
[Batsons].. 12
14. CONTENTS OF THE VERTEBRAL CANAL
Spinal cord
is a cylindrical, grayish-
white structure, 42-45 cm
in length that begins above
the foramen magnum,
where it is continuous with
the medulla oblongata of
the brain.
It terminates below in the
adult at the level of the
lower border of the first
lumbar vertebra.
In the young child it is
relatively longer and ends
at the upper border of the
third lumbar vertebra.
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15. BLOOD SUPPLY OF THE SPINAL CORD
The spinal cord receives its
arterial supply from three
small, longitudinally running
arteries-the two posterior
spinal arteries branches of
posterior inferior cerebellar
arteries and the one anterior
spinal artery branch of
Vertebral artery,
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16. The veins of the spinal
cord drain into the
internal vertebral
venous plexus
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17. Meninges of the spinal cord
1. Dura mater
the most external membrane
and is a dense, strong, fibrous
sheet that encloses the spinal
cord and cauda equina.
Continuous above through
the foramen magnum with
the meningeal layer of dura
covering the brain.
Inferiorly, it ends on the filum
terminale at the level of the
lower border of the second
sacral vertebra.
Epidural space- contains
loose areolar tissue and the
internal vertebral venous
plexus.
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18. 2. Arachnoid mater
a delicate impermeable
membrane covering the
spinal cord and lying
between the pia mater
internally and the dura
mater externally.
Separated from the dura
by the subdural space
that contains a thin film
of tissue fluid.
Separated from the pia
mater by a wide space,
the subarachnoid space,
which is filled with
cerebrospinal fluid.
Inferiorly , it ends on the
filum terminale.
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19. 3. Pia mater
A vascular membrane
that closely covers the
spinal cord.
Below it fuses with the
filum terminale
The pia mater is
thickened on either side
between the nerve roots
to form the ligamentum
denticulum, which
passes laterally to be
attached to the dura.
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20. LIGAMENTUM DENTICULATUM
These are the ribbon like
thickened bands of pia
mater,extending
laterally,piercing the arachnoid
and attached to the inner
surface of the duramater
The first teeth of denticulatum
lies at the level of foramen
magnum
The last betweenT12andL1
The lowest tooth is forked and
the posterior root of the L1 lie
at the outer prong of the fork
Serve as a guide in cardotomy
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22. CONUS MEDULLARIS and CAUDA
EQUINA
The roots of the nerves
lumbar, sacral and
coccygeal leave through
appropriate numbered
intervertebral foramen
They together look like
a horse tail-cauda
equina
The terminal end of the
spinal cord-conus
medullaris.
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25. EPIDURAL SPACE
Lies between the spinal
duramater and the
periosteum and
ligaments lining the
vertebral canal
1.loose areolar
connective tissue
2.semiliquid fat
3.spinal arteries
4.the internal vertebral
venous plexus.
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26. Applied anatomy
Lumbar epidural
anaesthesia
Between L3 and L4
spine n eedle course
through, skin, fat,
supraspinous and
interspinous ligaments,
ligamentum flava,
epidural space.
This space is confirmed
by the fact that it is a
space with negative
pressure
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27. CAUDAL EPIDURAL ANAESTHESIA
The needle is passed
through sacral hiatus
which lies equidistant
from the right and left
posterior superior iliac
spines and enters the
sacral canal
This space lies below
S2
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28. SUBDURAL SPACE
Is a potential space
between the duramater
and the arachnoid,
containing thin film of
serous fluid.
Permits movements of
dura over the arachnoid
Continued for a short
distance on to the spinal
nerve
Free comunication with
the lymph spaces
around the nerves
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30. SUB ARACHNOID SPACE
IS a wide space
between the pia and
the arachnoid filled
with CSF
Spinal sub arachnoid
space is wider then the
space around the brain
Widest below where it
encloses the caudae
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31. Applied aspects
LUMBAR PUNCTURE:
Done through the
Intervertabral disc
between L3 and L4 for
threuptic and diagnostic
purpose.
In children-vertabrel
level-L1.
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34. VERTESBRAL SYSTEM OF VEINS
The vertebral venous
system –
valveless,complicated
network ,with
longitudinal pattren
Runs parallel to SVC
andIVC and
anastomoses with
them
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36. This network has three
intercommunicatiing
sub divisions
1,the epiduralplexus lies
in the vertebral canal
outside the durameter
Consists of 1. postcentral
2.pre laminar portion
This plexus drains the
structures in the
vertebral canal
Itself drained at regular
intervals by
Segmental veins-
vertebral,posterior
intercostal,lumbar and
lateral sacral .
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37. Plexus within the
veretebral bodies-
drains backwards into
the epidural plexus
Anterolaterally-into
the external vertebral
plexus
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38. 3. External vertebral venous
plexus-
It consists of anterior vessels
lying in front of the vertebral
bodies
Posterior vessels on the back
of the vertebral arches and on
adjacent muscles- drained by
segmental veins
The sub occipital plexus of
veins lying in the sub occipital
triangle is a part of external
venous plexus
It receives the occipital veins
of the scalp – connected with
the transverse sinus by
emissary veins and drains into
the subclavian veins
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39. BATSON’S PLEXUS
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The azygos system also
communicates with a valveless
venous network known as
BATSON’S PLEXUS. When the
vena cava is partially or totally
occluded, Batson’s plexus
provides an alternate route for
blood return to the heart.
The vessels of Batson’s
plexus may be referred to as
epidural veins
Batson’s
plexus
40. Communications- valveless vertebral system of
veins communicates
1. Above with intracranial venous sinuses
2. Below with the pelvic veins, portal vein and caval
system of veins
The veins are valveless and so the blood can flow
in either direction
An increase in intra thoracic or intra abdominal
pressure due to coughing and straining may cause
blood to flow either upwards or downwards away
from heart
Such periodic changes in venous pressure are
clinically important
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41. There may possible spread of tumours or
infection-eg: cells from pelvic, abdominal
thoracic and breast tumours-venous system-
lodge in the vertebra, spinal cord, skull or the
brain
Primary sites of tumours causing secondaries in
vertebra are breast, prostate and kidney
Vertebral caries – tuberculous infection with in
the veretebrae
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