1. ANATOMY - DR.SANJIVANIANATOMY - DR.SANJIVANI
SPINAL ANAES - DR PALLAVISPINAL ANAES - DR PALLAVI
EPIDURAL ANAES - DR.TANZEEMEPIDURAL ANAES - DR.TANZEEM

2. INTRODUCTIONINTRODUCTION
Spinal & Epidural Anesthesia Techniques are blind procedures.Spinal & Epidural Anesthesia Techniques are blind procedures.
Even in expert hands chances of failure are high. Knowledge ofEven in expert hands chances of failure are high. Knowledge of
Anatomy increases success rate.Anatomy increases success rate.
Neurovascular structure eg.spinal cord is closely associated withNeurovascular structure eg.spinal cord is closely associated with
epidural space. So knowing anatomy & correct technique canepidural space. So knowing anatomy & correct technique can
reduce devasting complications.reduce devasting complications.
Real boon to patients with medical derangement & conditionsReal boon to patients with medical derangement & conditions
where GA is contraindicated.where GA is contraindicated.

4. COMPONENTSCOMPONENTS
 Vertebral columnVertebral column: forms a canal: forms a canal
for spinal cord & protect it.for spinal cord & protect it.
33 vertebrae:33 vertebrae:
Cervical - 7Cervical - 7
Thoracic – 12Thoracic – 12
Lumbar – 5 (4% cases – 6)Lumbar – 5 (4% cases – 6)
Sacral – 5Sacral – 5
CoccyxCoccyx
AA Typical vertebraeTypical vertebrae::
1) Body1) Body
2) Arch2) Arch
3) Processes:3) Processes:
2 transverse processes.2 transverse processes.
1 spinous process1 spinous process
4 articular pr.4 articular pr.

5. Gaps:Gaps:
1)1) Lateral intervertebral gap:Lateral intervertebral gap:
- gap between upper & lower pedicles.- gap between upper & lower pedicles.
- Forms intervertebral foramen from- Forms intervertebral foramen from
which nerve roots emerges.which nerve roots emerges.
2)2) Posterior interlaminar gap:Posterior interlaminar gap:
- formed by central part of lamina- formed by central part of lamina
which is relatively shallow.which is relatively shallow.
- Site of epidural & spinal punture.- Site of epidural & spinal punture.

6.  Ligaments:Ligaments: Supports vertebral column & provides stability.Supports vertebral column & provides stability.
1)1) Supraspinous:Supraspinous:
- Connecting apices of spines- Connecting apices of spines
- extent C-7 -- sacrum.- extent C-7 -- sacrum.
- Above C-7 blends with- Above C-7 blends with
ligamentum nuchaeligamentum nuchae
in neck & attach toin neck & attach to
external occipetalexternal occipetal
protuberance of skull.protuberance of skull.
2)2) Interspinous ligament:Interspinous ligament:
- Connect adjacent spines – upper- Connect adjacent spines – upper
& lower spine.& lower spine.

7. 3)3) Ligamentum flavum:Ligamentum flavum:
- most important ligament.- most important ligament.
- extend between lamina from the anterior- extend between lamina from the anterior
inferior surface of the upper laminainferior surface of the upper lamina
downward to the anterior superiordownward to the anterior superior
surface of the lower lamina.surface of the lower lamina.
- extends from foramen magnum – sacral- extends from foramen magnum – sacral
hiatus.hiatus.
- distance from skin – Ligamentum Flavum – 3 – 8 cm.- distance from skin – Ligamentum Flavum – 3 – 8 cm.
- cephalad – caudal thickness – 1.5 – 6 mm.- cephalad – caudal thickness – 1.5 – 6 mm.
4)4) Anterior & posterior longitudinal ligamentAnterior & posterior longitudinal ligament
joining body of vertebrae anterior & posteriorly.joining body of vertebrae anterior & posteriorly.

8. IMPIMP:: Needle inserted in spinal / Epidural A penetrateNeedle inserted in spinal / Epidural A penetrate
1)1) Midline approachMidline approach ::
SkinSkin
Subcutaneous tissue,Subcutaneous tissue,
Supraspinous ligamentSupraspinous ligament
Interspinous lig.Interspinous lig.
Lig. Flavum – 1st clickLig. Flavum – 1st click..
Epidural spaceEpidural space
Dura – 2 nd click.Dura – 2 nd click.
Subdural space.Subdural space.
Arachnoid matterArachnoid matter
Subarachanoid spaceSubarachanoid space
2)2) Paramedian approach:Paramedian approach:
Little resistance until Lig. Flavum.Little resistance until Lig. Flavum.
Needle passes lat. to supraspinousNeedle passes lat. to supraspinous
& interspinous lig and penetrates& interspinous lig and penetrates
Lig. Flavum & dura at midline.Lig. Flavum & dura at midline.

9.  Meninges of spinal cord:Meninges of spinal cord:
1) Dura matter.1) Dura matter.
2) Arachnoid matter2) Arachnoid matter
3) Pia matter—firmly attached to spinal cord.3) Pia matter—firmly attached to spinal cord.
Dura matterDura matter:: form sac around cordform sac around cord
- Continuation of meningeal inner layer of cranial dura- Continuation of meningeal inner layer of cranial dura
matter.matter.
-extends from foramen magnum to S2 vertebrae.-extends from foramen magnum to S2 vertebrae.
Subdural space:Subdural space:
-contains-contains small amount of serous fluid.small amount of serous fluid.
-accidental injection of drug -failed spinal A during SAB.-accidental injection of drug -failed spinal A during SAB.
-total spinal A if epidural drug-total spinal A if epidural drug

10. Arachnoid matterArachnoid matter :: delicate non-vascular structuredelicate non-vascular structure..
SA space :SA space :
- potential space lined externally- potential space lined externally
by – arachnoid matterby – arachnoid matter
- internally by pia matter close to spinal cord.- internally by pia matter close to spinal cord.
- contents : CSF- contents : CSF
- spinal nerve- spinal nerve
-denticulate ligament-denticulate ligament
-cobweb trabaculae-cobweb trabaculae
- shape : annular (3mm) – Cx , thoraxic region.- shape : annular (3mm) – Cx , thoraxic region.
circular – lumbarcircular – lumbar
Pia matter:Pia matter:
-highly vascular thin membrane covering cord,-highly vascular thin membrane covering cord,
terminates at phylum terminalae.terminates at phylum terminalae.
-gives lat. extension called denticulate lig.-gives lat. extension called denticulate lig.

11. Denticulate Ligament :Denticulate Ligament :
- folds of pia matter.- folds of pia matter.
- Struts holding spinal cord.- Struts holding spinal cord.
- attach to ant. & post. roots & fused with arachnoid- attach to ant. & post. roots & fused with arachnoid
matter & dura.matter & dura.
- contains elastic fibers – provides elasticity to &- contains elastic fibers – provides elasticity to &
acts as strutsacts as struts
- can leads to patchy or unilateral anaesthesia.- can leads to patchy or unilateral anaesthesia.

12. Anatomic curves of spineAnatomic curves of spine
supine positionsupine position
highest pt. – 3rd lumber.highest pt. – 3rd lumber.
low pt. – 5th thoraxiclow pt. – 5th thoraxic
IMPIMP -- deposition ofdeposition of
hypo / iso / hyperbarichypo / iso / hyperbaric
solution in SAB.solution in SAB.
 Normal curves of spineNormal curves of spine
-double ‘S’ shape..-double ‘S’ shape..

13.  Abnormal curves :Abnormal curves :
- kyphosis : exaggerated AP thoraxic curves- kyphosis : exaggerated AP thoraxic curves
- lordosis : lumber curves – physiological lordosis seen- lordosis : lumber curves – physiological lordosis seen
3rd trimester of pregnancy.3rd trimester of pregnancy.
- scoliosis : lateral curvature.- scoliosis : lateral curvature.
IMP :IMP : abn. curvature of spine can cause spinal or epidural Aabn. curvature of spine can cause spinal or epidural A
difficult or in extreme cases impossible.difficult or in extreme cases impossible.
so in PAC while doing spine examination noting curvatureso in PAC while doing spine examination noting curvature
of spine is very important.of spine is very important.

14. Developmental anatomy of spinal cord:Developmental anatomy of spinal cord:
Spinal cord develops from caudal part of neural tube & extendsSpinal cord develops from caudal part of neural tube & extends
throughout the length of vertebral column during fetal life.throughout the length of vertebral column during fetal life.
Rapid growth of vertebral column causes spinal cord to lag behind.Rapid growth of vertebral column causes spinal cord to lag behind.
so spinal cord ends at higher level.so spinal cord ends at higher level.
Meningeal covering also ends at higher level because they cannotMeningeal covering also ends at higher level because they cannot
keep pace with slow growth of spinal cord or fast growth ofkeep pace with slow growth of spinal cord or fast growth of
vertebral column.vertebral column.

15. Age Lower end of SC Dural sacAge Lower end of SC Dural sac
6th month of fetal life S1 S56th month of fetal life S1 S5
Birth L3 S3Birth L3 S3
1st year L2 (28%-L3) S2 (1st year L2 (28%-L3) S2 (no LP aboveno LP above
L4L4))
Adult ( upper border of L2 or S2Adult ( upper border of L2 or S2
lower border of L1) – 90%lower border of L1) – 90%
This differential growth of spinal cord &This differential growth of spinal cord &
vertebral column causes developmentvertebral column causes development
of caudal canal & epidural space.of caudal canal & epidural space.
..

16. IMP:IMP: Lumber punctureLumber puncture
In children NEVER ABOVE L4.In children NEVER ABOVE L4.
Adult preferably L3 – L4 interspace,Adult preferably L3 – L4 interspace,
In 10% population cord extends upIn 10% population cord extends up
to lower border of L2. So avoidto lower border of L2. So avoid
using L2 – L3 interspaceusing L2 – L3 interspace

17.  Spinal nerves:Spinal nerves:
31 pairs of nerves:31 pairs of nerves:
Cx -- 8Cx -- 8
Thoracic -- 12Thoracic -- 12
Lumber – 5Lumber – 5
Sacral -- 5Sacral -- 5
Coccyx – 1Coccyx – 1
Each nerve anterior roots –motor intervertebralEach nerve anterior roots –motor intervertebral
foramenforamen
Posterior roots – sensoryPosterior roots – sensory
IMP :IMP : passage of nerve through intervertebral foramen is the site of action ofpassage of nerve through intervertebral foramen is the site of action of
drug given in epidural anaesthesiadrug given in epidural anaesthesia..

18. Each nerve supplies –Each nerve supplies –
body wallbody wall
Vertebral muscles dermatomeVertebral muscles dermatome
Overlying skinOverlying skin
And communicates with sympathetic chainAnd communicates with sympathetic chain
through white and grey rami.through white and grey rami.
spinal nerve roots are not uniform inspinal nerve roots are not uniform in
size or structure bilaterally.size or structure bilaterally.
IMPIMP-Large inter individual variability –-Large inter individual variability –
differences in level of Neuroaxialdifferences in level of Neuroaxial
blocked quality even same amountblocked quality even same amount
of drug is given.of drug is given.

19. Topographic line of Tuffier:Topographic line of Tuffier:
Line across back, between crest of illia passes over spine of L4 in uprightLine across back, between crest of illia passes over spine of L4 in upright
position.position.
In lying down position passes through L4 – L5.In lying down position passes through L4 – L5.
IMP:IMP: acts as landmark on back for identification & numbering of interspaceacts as landmark on back for identification & numbering of interspace
between spinous process of vertebrae.between spinous process of vertebrae.

20. Blood supply of spinal cord:Blood supply of spinal cord:
 Anterior spinal artery:Anterior spinal artery:
- Formed at foramen magnum by a branch from terminal- Formed at foramen magnum by a branch from terminal
portion of each vertebral A.portion of each vertebral A.
- Runs along Anterior median fissure & descends whole length.- Runs along Anterior median fissure & descends whole length.
- Supplies anterior 2/3 of spinal cord.- Supplies anterior 2/3 of spinal cord.

21.  Posterior spinal artery:Posterior spinal artery:
- 4 longitudinally running vessels -2 on each side- 4 longitudinally running vessels -2 on each side
- Originates at base of brain from vertebral A or Posterior inferior- Originates at base of brain from vertebral A or Posterior inferior
cerebellar A.cerebellar A.
- Supplies – posterior 1/3 of spinal cord- Supplies – posterior 1/3 of spinal cord
 Reinforcement:Reinforcement:
- Spinal radicular branches from local segmental A- Spinal radicular branches from local segmental A
(derived from aorta)(derived from aorta)
-vertebral-vertebral
-Ascending cervical-Ascending cervical
-Posterior intercostal-Posterior intercostal
-Spinal lumbar-Spinal lumbar
-Lateral sacral A-Lateral sacral A

22. - Forms anastomoses with anterior & posterior spinal A.- Forms anastomoses with anterior & posterior spinal A.
- Posterior radicular br. are larger & numerous.- Posterior radicular br. are larger & numerous.
- Large radicular A. are found at upper thoraxic (T1) &- Large radicular A. are found at upper thoraxic (T1) &
upper lumber L1.upper lumber L1.
- Most of radicular br. are small & terminates in ventral N- Most of radicular br. are small & terminates in ventral N
root or in plexus of pia matter around cord.root or in plexus of pia matter around cord.

23. Arteria radicularis magna (A of Adam kewiz):Arteria radicularis magna (A of Adam kewiz):
Large ant. radicular A.Large ant. radicular A.
Derived directly from thoraxicDerived directly from thoraxic
aorta mostly on left side.aorta mostly on left side.
Provide rich reinforcement toProvide rich reinforcement to
ant. Spinal A. in Lumber area.ant. Spinal A. in Lumber area.
Responsible for major bloodResponsible for major blood
supply of lower 2/3 ofsupply of lower 2/3 of
spinal cord in 50% population.spinal cord in 50% population.

24. Peculiarity of blood supply of spinal cord:Peculiarity of blood supply of spinal cord:
Each cm of spinal cord receives 5-8 br. WhichEach cm of spinal cord receives 5-8 br. Which
penetrates substance of cord.penetrates substance of cord.
No anastomoses seen in this penetrating br.No anastomoses seen in this penetrating br.
so they act as end vessels.so they act as end vessels.
There is no anastomoses between ant. &There is no anastomoses between ant. &
post. Spinal A.post. Spinal A.
However overlapping of territories seenHowever overlapping of territories seen
between ant. & post. spinal A.between ant. & post. spinal A.
IMP:IMP:
Delicate System because of endDelicate System because of end
artery structure.artery structure.
Quite vulnerable to minor trauma &Quite vulnerable to minor trauma &
vasoconstrictor drugs.vasoconstrictor drugs.
Ant. spinal A syndrome.Ant. spinal A syndrome.
Cauda equina syndrome.Cauda equina syndrome.

25. Veins of spinal cordVeins of spinal cord
Six veins – longitudinal plexiformSix veins – longitudinal plexiform
MedianMedian
4 lateral longitudinal veins – communicates with4 lateral longitudinal veins – communicates with
int.vertebral pr. ext. vertebral plexusint.vertebral pr. ext. vertebral plexus
–– K/a Batson plexus which is valveless.K/a Batson plexus which is valveless.
Veins draining spinal cord, vertebral column & meninges.Veins draining spinal cord, vertebral column & meninges.
Forms:Forms:
External plexusExternal plexus both are valveless & anastomoses freelyboth are valveless & anastomoses freely
with each other.with each other.
Internal plexusInternal plexus

26. Veins of vertebral column constitute venous system parallel to mainVeins of vertebral column constitute venous system parallel to main
caval system.caval system.
Extensive communication thr. SegmentsExtensive communication thr. Segments
Increase pressure in abdomen or thorax increases blood flow thr.Increase pressure in abdomen or thorax increases blood flow thr.
vertebral system rather than caval system.vertebral system rather than caval system.
IMP:IMP:
In condition with increase abd pressure e.g. Pregnancy epidural veinIn condition with increase abd pressure e.g. Pregnancy epidural vein
tortuous causing decrease in subarachanoid space – reducedtortuous causing decrease in subarachanoid space – reduced
quantity of drug required for SAB.quantity of drug required for SAB.
More absorption of drug by epidural veins so systemic toxicity ofMore absorption of drug by epidural veins so systemic toxicity of
drugs achieves earlier than other pts.drugs achieves earlier than other pts.

29. Anatomy:Anatomy:
- Space between periosteum & dura.- Space between periosteum & dura.
- Circular space surrounding dura.- Circular space surrounding dura.
- Extends from foramen magnum- Extends from foramen magnum
to coccyx.to coccyx.
- Cranially bounded at foramen- Cranially bounded at foramen
magnum where periostealmagnum where periosteal
layer fuses with dural layer &layer fuses with dural layer &
lower caudal limit is bylower caudal limit is by
sacrococcaygel membrane.sacrococcaygel membrane.
- Anteriorly – post. Long. Ligament.- Anteriorly – post. Long. Ligament.
- Posteriorly. – Lig. Flavum.- Posteriorly. – Lig. Flavum.
- Laterally. – pedicles and- Laterally. – pedicles and
intervertebral foramen.intervertebral foramen.

30. ..
Needle in epidural space penetratesNeedle in epidural space penetrates::
Skin & subcutaneous tissue.Skin & subcutaneous tissue.
Supraspinous ligament.Supraspinous ligament.
Interspinous ligament.Interspinous ligament.
Ligamentum Flavum.Ligamentum Flavum.
Width:Width:
Semi / half moon shape.Semi / half moon shape.
1 –1. 5 mm (C1- C2 level.)1 –1. 5 mm (C1- C2 level.)
1 – 6 mm (sacral.)1 – 6 mm (sacral.)
distance from skin-Adult male – 4.7 cm( at L3 – L4.)distance from skin-Adult male – 4.7 cm( at L3 – L4.)
Width Epidural space (mm) Thickness of duraWidth Epidural space (mm) Thickness of dura
Cx 1.0 – 1.5 2.0 – 1.5Cx 1.0 – 1.5 2.0 – 1.5
Upper thoraxicUpper thoraxic 2.5 – 3.0 12.5 – 3.0 1
Lower thoraxic 4 – 5 1Lower thoraxic 4 – 5 1
Lumbar 5 – 6 0.66 – 0.33Lumbar 5 – 6 0.66 – 0.33

31. Factors affecting Epidural depthFactors affecting Epidural depth :: Maximum depth at L3 – L4.Maximum depth at L3 – L4.
1) Weight1) Weight
2) Technique2) Technique
3) Angle of needle.3) Angle of needle.
4) Position of patient.4) Position of patient.
5) Ethnic origin.5) Ethnic origin.
6) Edema.6) Edema.
Contents:Contents:
1)1) Connective tissue:Connective tissue:
Strong bands & connection between dura & ant. Long. Ligament –Strong bands & connection between dura & ant. Long. Ligament –
So space is practically non-existent. Space is more extensiveSo space is practically non-existent. Space is more extensive
& distensible posteriorly.& distensible posteriorly.
2)2) Epidural veins:Epidural veins:
Valveless veins from int. vertebral venous plexus.Valveless veins from int. vertebral venous plexus.
Venacaval compression distends epidural vein so decreased doseVenacaval compression distends epidural vein so decreased dose
is required in pregnancy.is required in pregnancy.

32. 3)3) Spinal arteriesSpinal arteries..
4)4) Epidural lymphaticsEpidural lymphatics::
5)5) Epidural fatEpidural fat: In children less than 6: In children less than 6
years has spongy, gelateneous lobules &years has spongy, gelateneous lobules &
distinct space so more rapid spread of drug.distinct space so more rapid spread of drug.
Plica mediana dorsalis:Plica mediana dorsalis:
Dorsomedian connective tissue betweenDorsomedian connective tissue between
dura & ligamentum flavum .Seen moredura & ligamentum flavum .Seen more
extensively in area of spinal curves .extensively in area of spinal curves .
Located in midline which may divideLocated in midline which may divide
epidural space into right & left halvesepidural space into right & left halves
& narrow space in midline. In some& narrow space in midline. In some
persons a complete membrane inpersons a complete membrane in
dorsomedian plane seen between duradorsomedian plane seen between dura
and ligamentum flavumand ligamentum flavum
k /a plica mediana dorsalis .k /a plica mediana dorsalis .

33. IMP:IMP:
Difficulty in insertion of needle or catheter in midline – can results intoDifficulty in insertion of needle or catheter in midline – can results into
deposition of drug slightly on one or other side.deposition of drug slightly on one or other side.
Can lead to spotty / unilateral anaesthesia.Can lead to spotty / unilateral anaesthesia.
Difficulty in advancing catheter freely.Difficulty in advancing catheter freely.
Can cause coiling of epidural catheter inside.Can cause coiling of epidural catheter inside.

34. Pressure in Epidural space:Pressure in Epidural space:
-- Negative pressureNegative pressure
- More at sites of firm attachment thoraxic (up to -15)>lumbar- More at sites of firm attachment thoraxic (up to -15)>lumbar
>sacral>sacral
- Non-existence in Cx & sacral area.- Non-existence in Cx & sacral area.
- 12% have no negative pressure so techniques using negative- 12% have no negative pressure so techniques using negative
pressure for detection of space is not useful in such pts.pressure for detection of space is not useful in such pts.
Factors affecting negative pressure:Factors affecting negative pressure:
1) Marked flexion1) Marked flexion
2) Young person2) Young person
3) Old people with ligament changes3) Old people with ligament changes
4) pt. straining & tense4) pt. straining & tense

35. Thoracic Epidural AnatomyThoracic Epidural Anatomy
- Spinous pr. in upper thoraxic T1 - T4- Spinous pr. in upper thoraxic T1 - T4
& T10 – T12 are more horizontal.& T10 – T12 are more horizontal.
- In midthoracic region – pr. are- In midthoracic region – pr. are
angulated in such a way that the tipangulated in such a way that the tip
of spinous process of upperof spinous process of upper
vertebrae rest on origin of lowervertebrae rest on origin of lower
spinous pr.spinous pr.
- Because of this anatomical difficulty- Because of this anatomical difficulty
it is difficult to attempt a midlineit is difficult to attempt a midline
entry into epidural space.entry into epidural space.

36. -So midline approach can be usedSo midline approach can be used
for upper or lower thoracic region.for upper or lower thoracic region.
- In midthoracic region paramedian- In midthoracic region paramedian
approach is preferred whichapproach is preferred which
however can perform at any level.however can perform at any level.
- Only marginal increase in space- Only marginal increase in space
achieved by flexion of spineachieved by flexion of spine
- however this small increase can- however this small increase can
facilitate entry of thick epiduralfacilitate entry of thick epidural
needle.needle.

37. - While using hanging drop technique for identification of space pt. should- While using hanging drop technique for identification of space pt. should
assume sitting position because of increase in negative pressure inassume sitting position because of increase in negative pressure in
sitting position.sitting position.
- with loss of resistance technique lateral & sitting decubitus can be used.- with loss of resistance technique lateral & sitting decubitus can be used.
- Thoracic epidural –carries more risk & complication.- Thoracic epidural –carries more risk & complication.

38. CERVICAL EPIDURAL SPACECERVICAL EPIDURAL SPACE
Cx spinal pr. are not angulated & horizontalCx spinal pr. are not angulated & horizontal
approach is indicated as in lumbar region.approach is indicated as in lumbar region.
C7 – T1 is widest, easiest space to use.C7C7 – T1 is widest, easiest space to use.C7
is prominent landmark.is prominent landmark.
Sitting position is used because of betterSitting position is used because of better
palpation of C7 process.palpation of C7 process.

39. Lig. Flavum is quite thin & can be reached quiteLig. Flavum is quite thin & can be reached quite
superficially.superficially.
A gentle click may be appreciated while piercingA gentle click may be appreciated while piercing
Lig. Flavum.Lig. Flavum.
At C6 – C7 or C7 – T1 epidural space width—3 – 4 mm whichAt C6 – C7 or C7 – T1 epidural space width—3 – 4 mm which
becomes narrower in higher segments where meningeal dura &becomes narrower in higher segments where meningeal dura &
endosteal dura fuses at foramen magnum.endosteal dura fuses at foramen magnum.

41. Anatomy of sacrumAnatomy of sacrum::
Triangular shaped bone.Triangular shaped bone.
Fusion of lamina of five vertebralFusion of lamina of five vertebral
segments by 20 th year of life.segments by 20 th year of life.
A part of pelvis.A part of pelvis.
Anterior surface – smooth supportingAnterior surface – smooth supporting
vessels, rectum, fetal head.vessels, rectum, fetal head.
Posterior surface – rough forms sacralPosterior surface – rough forms sacral
crest (fusion of spinous processes)crest (fusion of spinous processes)

42. Fifth spinous process is unfused.Fifth spinous process is unfused.
Failure of this fusion results inFailure of this fusion results in
HIATUS.HIATUS.
V or U shaped notch.V or U shaped notch.
Unfused lamina on each sideUnfused lamina on each side
forms cornua.forms cornua.
Communicates with sacral portionCommunicates with sacral portion
of vertebral column.of vertebral column.
Covered by sacrococcaygelCovered by sacrococcaygel
ligament.ligament.

43. On each side of midline 4 pairs of foramina transmitting anterior divisionOn each side of midline 4 pairs of foramina transmitting anterior division
of spinal nerves are formed. Fifth is absent.of spinal nerves are formed. Fifth is absent.
Sacral canal:Sacral canal:
- Continuation of vertebral canal.- Continuation of vertebral canal.
- Curved – 3-4 inch longitudinal triangular space.- Curved – 3-4 inch longitudinal triangular space.
- Dural sac fills completely the vertebral canal except potential epidural- Dural sac fills completely the vertebral canal except potential epidural
space.space.
- Sac ends between S1 – S2 vertebrae.- Sac ends between S1 – S2 vertebrae.

44. - Mean distance between apex of hiatus and dural sac is 47 mm.- Mean distance between apex of hiatus and dural sac is 47 mm.
- As child grows up – axis of sacrum compared to lumber spine- As child grows up – axis of sacrum compared to lumber spine
changes so sacral hiatus becomes difficult to locate & may evenchanges so sacral hiatus becomes difficult to locate & may even
close.close.
Contents:Contents:
- Fluidy fat & loose areolar tissue- Fluidy fat & loose areolar tissue
- Epidural veins- Epidural veins

45. ANATOMIC CONSIDERATION Of NEUROAXIAL BLOCKADEANATOMIC CONSIDERATION Of NEUROAXIAL BLOCKADE
(in pediatrics patients.)(in pediatrics patients.)
Procedures:Procedures:
1) Caudal A1) Caudal A
2) Epidural A:2) Epidural A:
a) Intervertebral routea) Intervertebral route
ThoracicThoracic
LumbarLumbar
b) Sacral epiduralb) Sacral epidural
3) Spinal A3) Spinal A

46. Caudal A:Caudal A:
- Mainly performed in infants & young children,- Mainly performed in infants & young children,
usually combined with light GA.usually combined with light GA.
- Fluidity of epidural fat – easy to introduce a catheter in epidural- Fluidity of epidural fat – easy to introduce a catheter in epidural
space for long lasting analgesia.space for long lasting analgesia.
- This approach can be used to introduce catheter which can be- This approach can be used to introduce catheter which can be
threaded cranially to perform lumber / thoracic A with outthreaded cranially to perform lumber / thoracic A with out
approaching the epidural space through lumber / thoracicapproaching the epidural space through lumber / thoracic
intervertebral space.intervertebral space.
- Distance from skin to sacral epidural space < 20 mm from skin- Distance from skin to sacral epidural space < 20 mm from skin
& not influenced by age / weight.& not influenced by age / weight.

47. Intervertebral epidural A:Intervertebral epidural A:
- Because subcutaneous tissue & vertebral ligaments are less- Because subcutaneous tissue & vertebral ligaments are less
densely packed in infants & young children LOR felt asdensely packed in infants & young children LOR felt as
needle advances Lig. Flavum is LESS SIGNIFICANT than in adults.needle advances Lig. Flavum is LESS SIGNIFICANT than in adults.
- Midline approach is safer than paramedian approach.- Midline approach is safer than paramedian approach.
- Previous epidural A – may result in proliferation of connective tissue,- Previous epidural A – may result in proliferation of connective tissue,
Adhesion forms between dura matter & Lig. Flavum due toAdhesion forms between dura matter & Lig. Flavum due to
inflammation which reduces spread of LA during next epidural A.inflammation which reduces spread of LA during next epidural A.
- In pts. > 6 years, for continuous analgesia technique intervertebral epidural- In pts. > 6 years, for continuous analgesia technique intervertebral epidural
approach is preferred over caudal approach.approach is preferred over caudal approach.

48. 1)1) Lumbar Epidural ALumbar Epidural A
- Spinal cord ends at lower level in children. Safer to select- Spinal cord ends at lower level in children. Safer to select
L4 – L5 vertebrae or L5 – S1 space for epidural.L4 – L5 vertebrae or L5 – S1 space for epidural.
- Line joining to illiac creast – L5 vertebrae – anatomic landmark.- Line joining to illiac creast – L5 vertebrae – anatomic landmark.
- Distance from skin – epidural space varies with pts. age & size- Distance from skin – epidural space varies with pts. age & size
1 mm / kg – (6 mth – 10 years).1 mm / kg – (6 mth – 10 years).

49. 2)2) Sacral Epidural A:Sacral Epidural A:
- In children because of incomplete ossification of sacrum there are true- In children because of incomplete ossification of sacrum there are true
posterior sacral interspace suitable for epidural approach at anyposterior sacral interspace suitable for epidural approach at any
sacral level.sacral level.
- Easiest through S2 – S3 in lateral position.- Easiest through S2 – S3 in lateral position.
- Interspace located by line joining 0.5 – 1 cm below two PSIS.- Interspace located by line joining 0.5 – 1 cm below two PSIS.
- Distance from skin – epidural space is less than at lumber level- Distance from skin – epidural space is less than at lumber level
because of lack of lumber lordosis.because of lack of lumber lordosis.
- Can be used as alternative procedure to caudal A & lumbar A. when- Can be used as alternative procedure to caudal A & lumbar A. when
inapplicable / failure.inapplicable / failure.
- Since sacral vertebrae not fused possible damage to ossification- Since sacral vertebrae not fused possible damage to ossification
nuclei & danger of crossing cartilaginous structure – use short,nuclei & danger of crossing cartilaginous structure – use short,
short bevel & not too thin caudal, epidural or spinal needle.short bevel & not too thin caudal, epidural or spinal needle.

50. 3)3) Thoracic epidural A:Thoracic epidural A:
-- Rarely performed in pead pts.Rarely performed in pead pts.
- Midline or paramedian approach can be used.- Midline or paramedian approach can be used.
- Whatever route used this approach is hazardous because of- Whatever route used this approach is hazardous because of
danger of direct trauma to spinal cord.danger of direct trauma to spinal cord.
- Must be performed by expert anesthetists on anaesthetized children.- Must be performed by expert anesthetists on anaesthetized children.

51. Spinal A:Spinal A:
- Subarachanoid space is incompletely divided by denticulate Lig. laterally &- Subarachanoid space is incompletely divided by denticulate Lig. laterally &
SA septum anteriorly.SA septum anteriorly.
Volume of CSF (4 ml / kg) is double than adults (2 ml / kg).Volume of CSF (4 ml / kg) is double than adults (2 ml / kg).
50% of CSF volume in spinal SA space.50% of CSF volume in spinal SA space.
influencesinfluences
pharmacokineticspharmacokinetics
CSF pressure 30 – 40 cm of H2O in recumbent pts. again of drug.CSF pressure 30 – 40 cm of H2O in recumbent pts. again of drug.
decrease in anaesthetized childrendecrease in anaesthetized children

52. - As in adults, Artery of admkiwiz entering spinal cord at T8 – L3- As in adults, Artery of admkiwiz entering spinal cord at T8 – L3
responsible for major blood supply of spinal cord.responsible for major blood supply of spinal cord.
- Any lesion of this Artery can lead to spinal ischemia & subsequent- Any lesion of this Artery can lead to spinal ischemia & subsequent
permanent paraplegia.permanent paraplegia.
- Younger is pt. – shorter is duration of block.- Younger is pt. – shorter is duration of block.
- Especially useful in pts. – Premature babies age < 4 mth of age who born- Especially useful in pts. – Premature babies age < 4 mth of age who born
premature & suffered from neonatal respiratory distress or who are atpremature & suffered from neonatal respiratory distress or who are at
risk of developing apnea following GA.risk of developing apnea following GA.