The document provides an overview of the anatomy of the vertebral column. It discusses the 33 vertebrae that make up the spine, their typical features, and variations in different regions. It describes the protective, supportive, and weight-bearing functions of the vertebral column. Key structures like the intervertebral discs, spinal cord, meninges, nerve roots, and blood supply are summarized. Considerations for regional anesthesia techniques and anatomical variations are also covered at a high level.

1. ANATOMY OF VERTEBRAL
COLUMN
SPEAKER – DR. SHARVANI
MODERATOR- DR. VIKAS

2. INTRODUCTION
• The vertebral column forms part of the axis of the human body,
extending in the midline from the base of the skull to the pelvis.
• Its four primary functions are
1. protection of the spinal cord
2. support of the head
3. provision of an attachment point for the upper extremities.
4. transmission of weight from the trunk to the lower extremities.
Pertinent to regional anesthesia, it serves as the landmark for a wide
variety of regional anesthesia techniques.

3. • The vertebral column consists of 33 vertebrae
(7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 4
coccygeal segments)
• In the embryonic period, the spine curves into a
C shape, forming two primary curvatures with
their convex aspect directed posteriorly.
• These curvatures persist through adulthood as
the thoracic and sacral curves.
• The cervical and lumbar lordoses are secondary
curvatures that develop after birth as a result of
extension of the head and lower limbs when
standing erect.
• The secondary curvatures are convex anteriorly
and augment the flexibility of the spine.

4. VERTEBRAE
• A typical vertebra consists of a vertebral arch posteriorly and a body
anteriorly.
• This holds true for all vertebrae except C1.
• Two pedicles arise on the posterolateral aspects of each vertebra and
fuse with the two laminae to encircle the vertebral foramen.
• These structures form the vertebral canal, which contains the spinal
cord, spinal nerves, and epidural space.

5. • Fibrocartilaginous disks containing the
nucleus pulposus- an avascular
gelatinous body surrounded by the
collagenous lamellae of the annular
ligament, join the vertebral bodies.
• The transverse processes arise from
the laminae and project laterally,
whereas the spinous process projects
posteriorly from the midline union of
the laminae.
• The spinous process is frequently bifid
at the cervical level and serves as an
attachment for muscles and
ligaments.

6. ATYPICAL VERTEBRAE
• C1 (atlas), C2 (axis), and C7 (vertebra
prominens) are described as atypical cervical
vertebrae due to their unique features.
C1
ringlike bone that has no body or spinous
process.
• It is formed by two lateral masses with facets
that connect anteriorly to a short arch and
posteriorly to a longer, curved arch.
• The anterior arch articulates with the dens,
and the posterior arch has a groove where
the vertebral artery passes

7. C2
• The odontoid process (dens) of C2
protrudes superiorly, hence the name
axis.
• Together, the atlas and axis form the
axis of rotation for the atlantoaxial joint.
C7
• The C7 (vertebra prominens) has a long,
non-bifid spinous process that serves as
a useful landmark for a variety of
regional anesthesia procedures.
• The C7 transverse process is large and
has only one posterior tubercle

8. • The interlaminar spaces in the thoracic spine are narrow and more
challenging to access with a needle due to overlapping laminae.
• In contrast, the laminae of the five lumbar vertebrae do not overlap.
• The interlaminar space between adjacent lumbar vertebrae is rather
large.

9. Vertebral facet (zygapophyseal) joints articulate posterior elements of adjacent
vertebrae.
• The junction of the lamina and pedicles gives rise to inferior and superior
articular processes
• The inferior articular process protrudes caudally and overlaps the inferiorly
adjacent vertebra’s superior articular process.
• This alignment is important to understand when performing interventional pain
procedures such as facet joint injections, intra-articular steroid injections or
radio-frequency denervation.

10. SACRUM
• Five sacral vertebrae fuse to form the
wedge-shaped sacrum, which connects
the spine with the iliac wings of the
pelvis.
• In childhood, the sacral vertebrae are
connected by cartilage, which
progresses to osseous fusion after
puberty, with only a narrow remnant of
sacral disk remaining in adulthood.
• Fusion is generally complete through the
S5 level, although there can be complete
lack of any posterior bony roof over the
sacral vertebral canal.

11. • The sacral hiatus is an opening formed
by the incomplete posterior fusion of
the fifth sacral vertebra.
• It lies at the apex of the coccyx, which is
formed by the union of the last four
vertebrae.
• This hiatus provides a convenient
access to the caudal ending of the
epidural space, especially in children.
• The sacral cornu are bony prominences
on each side of the hiatus that are
easily palpated in small children and
serve as landmarks for a caudal
epidural block.

12. INTERVERTEBRAL LIGAMENTS
The vertebral column is stabilized by a series of ligaments.
• The anterior and posterior longitudinal ligaments run along the anterior
and posterior surfaces of the vertebral bodies, respectively, reinforcing the
vertebral column.
• The supraspinous ligament, a heavy band that runs along the tips of the
spinous processes, becomes thinner in the lumbar region.
• This ligament continues as the ligamentum nuchae above T7 and attaches
to the occipital external protuberance at the base of the skull.
• The interspinous ligament is a narrow web of tissue that attaches between
spinous processes- anteriorly it fuses with the ligamentum flavum and
posteriorly with the supraspinous ligament.

14. Ligamentum flavum
dense, homogenous structure, composed mostly of elastin which
connects the lamina of adjacent vertebrae.
• The lateral edges of the ligamentum flavum surround facet joints
anteriorly, reinforcing their joint capsule.
• When a needle is advanced toward the epidural space, there is an easily
perceptible increase in resistance when the ligamentum flavum is
encountered.
• More importantly for the practice of neuraxial anesthesia, a perceptible,
sudden loss of resistance is encountered when the tip of the needle
passes through the ligamentum and enters the epidural space

15. • The ligamentum flavum is thinnest in the cervical and upper thoracic
regions and thickest in the lower thoracic and lumbar regions.
• As a result, resistance to needle advancement is easier to appreciate
when a needle is introduced at a lower level (eg, lumbar).
• At the L2–L3 interspace, the ligamentum flavum is 3- to 5-mm thick.
• At this level, the distance from the ligamentum to the spinal meninges is
4–6 mm.
• Consequently, a midline insertion of an epidural needle at this level is
least likely to result in an inadvertent meningeal puncture with epidural
anesthesia-analgesia.

16. • The ligamentum flavum consists of right and left halves
that join at an angle of less than 90°.
• Importantly, this midline fusion may be absent to a
variable degree depending on the vertebral level.
• These fusion gaps allow for veins to connect to
vertebral venous plexuses.
• The fusion gaps are more prevalent at cervical and
thoracic levels.
• The incidence of the midline gap decreases at lower
vertebral levels, with T4–T5 the lowest (8%).
• In theory, a midline gap poses a risk of failure to
recognize a loss of resistance at the cervical and high
thoracic levels when using the midline approach,
resulting in an inadvertent dural puncture.

17. INTERVERTEBRAL FORAMINA
• The lateral wall of the vertebral
canal has gaps between
consecutive pedicles known as
intervertebral foramina
• Because the pedicles attach more
cephalad of the middle of the
vertebral body, the intervertebral
foramina are centered opposite
the lower half of the vertebral
body, with the vertebral disk at
the caudal end of the foramen.

18. SPINAL CORD
• The spinal cord is an extension of the
medulla oblongata. It has three covering
membranes: the dura, arachnoid, and
pia maters
• These membranes concentrically divide
the vertebral canal into three distinct
compartments: the epidural, subdural,
and subarachnoid spaces.
• Cerebrospinal fluid (CSF) is contained
between the pia and arachnoid maters
in the subarachnoid space

20. • The epidural space is potential space within the spinal canal that is
bounded by the dura and the ligamentum flavum - contains fat, epidural
veins, spinal nerve roots, and connective tissue.
• The subdural space is a “potential” space between the dura and the
arachnoid and contains a serous fluid.
• The subdural compartment is formed by flat neuroepithelial cells that
have long interlacing branches. These cells are in close contact with the
inner dural layers.

21. • The subarachnoid space is traversed by threads of connective tissue
extending from the arachnoid mater to the pia mater. It contains the
spinal cord, dorsal and ventral nerve roots, and cerebrospinal fluid (CSF).
• The subarachnoid space ends at the S2 vertebral level.
• The main subarachnoid structure is a variably fenestrated partition, the
subarachnoid septum or septum posticum, which extends from the
posterior midline of the cord to the inner aspect of the arachnoid.
• Particularly relevant to the anesthesiologist is the occurrence of cysts
within the subarachnoid space, formed as saccular dilatations of the
septum posticum.
• Injection of drug into these collections of loculated CSF is a potential
cause of inadequate spinal anesthesia.

23. SPINAL NERVES:
• Dorsal(afferent) and ventral(efferent) nerve roots merge distal to dorsal root
ganglion to form spinal nerves.
• There are 31 pairs of spinal nerves- 8 cervical , 12 thoracic, 5 lumbar, 5
sacral, 1 coccygeal.
• Pass through intervertebral foramen, ensheathed by the dura,arachnoid and
pia mater , which respectively become epineurium, perineurium and
endoneurium.
• 2 enlargements in spinal cord- cervical and lumbar- gives rise to Brachial
plexus and Lumbar plexus respectively.

25. • The vertebral canal contains the dural sac, which adheres superiorly to
the foramen magnum, to the posterior longitudinal ligament anteriorly,
the ligamentum flavum and laminae posteriorly, and the pedicles
laterally.
• The dural sac is continuous from the foramen magnum to the sacral
region, where it spreads distally to cover the filum terminale.
• In children, the dural sac terminates lower, and in some adults, the sac
termination can be as high as L5.

26. • The cauda equina(“horse’s tail”) is a
bundle of nerve roots in the
subarachnoid space distal to the
conus medullaris.
• Therefore, performing a lumbar
(subarachnoid) puncture below L1 in
an adult (L3 in a child) usually avoids
potential needle trauma to the spinal
cord; damage to the cauda equina is
unlikely, as these nerve roots float in
the dural sac below L1 and tend to be
pushed away (rather than pierced) by
an advancing needle.
• The filum terminale, a fibrous
extension of the spinal cord, extends
caudally to the coccyx.

27. • The spinal cord normally extends from
the foramen magnum to the level of
L1 in adults.
• In children, the spinal cord ends at L3
and moves up with age.

28. BLOOD SUPPLY OF SPINAL CORD
• The spinal cord receives blood primarily
from one anterior and two posterior spinal
arteries that derive from the vertebral
arteries.
• Other major arteries that supplement
blood supply to the spinal cord include the
vertebral, ascending cervical, posterior
intercostal, lumbar, and lateral sacral
arteries.
• The single anterior spinal artery and two
posterior spinal arteries run longitudinally
along the length of the cord and combine
with segmental arteries in each region.

29. • The major segmental artery (Adamkiewicz) is the largest segmental
artery and is found between the T8 and L1 vertebral segments.
• The Adamkiewicz artery is the major blood supplier to two-thirds of the
spinal cord. Injury of this artery may result in anterior spinal artery
syndrome, characterized by loss of urinary and fecal continence as well
as impaired motor function of the legs.
• The radicular arteries are branches of the spinal arteries and run within
the vertebral canal and supply the vertebral column.
• Radicular veins drain blood from the vertebral venous plexus and
eventually drain into the major venous system: the superior and
inferior vena cava and the azygos venous system of the thorax.

33. MOVEMENTS OF THE SPINE
• The fundamental movements through the vertebral column are flexion,
extension, rotation, and lateral flexion in the cervical and lumbar spine.
• Movement between individual vertebrae is relatively limited, although
the effect is compounded along the entire spine.
• Thoracic vertebrae, in particular, have limited mobility due to the rib
cage.
• Flexion is greatest in the cervical spine, whereas extension is greatest in
the lumbar region.
• The thoracic and sacral regions are the most stable.

35. SPECIAL CONSIDERATIONS
• Elderly patients present anesthetic challenges when neuraxial techniques
are required.
• The frequency of spinal deformities in older adults can be as high as 70%
• There is an increased prevalence of spinal deformities, such as spinal
stenosis, scoliosis, hyperkyphosis, and hyperlordosis.
• With advancing age, a diminishing thickness of intervertebral disks results
in decreased height of the vertebral column.
• Thickened ligaments and osteophytes also contribute to difficulty in
accessing both the subarachnoid and epidural spaces.

36. ANATOMICAL VARIATIONS
1. NERVE ROOTS
• The spinal nerve roots are not uniform in size and structure.
• These differences may help to explain the interpatient differences in
neuraxial block quality when equivalent techniques are used on
seemingly similar patients.
• Another anatomic relationship may affect neuraxial blocks - although
generally larger than the ventral (motor) roots, the dorsal (sensory)
roots are often blocked more easily.
• This apparent paradox is explained by organization of the dorsal roots
into component bundles, which creates a much larger surface area on
which the local anesthetics act, possibly explaining why larger sensory
nerves are blocked more easily than smaller motor nerves

37. 2. CEREBROSPINAL FLUID
• Lumbosacral CSF has a constant pressure of approximately 15 cm
H2O, but its volume varies by patient, in part because of differences
in body habitus and weight.
• It is estimated that CSF volume accounts for 80% of the variability in
peak block height and regression of sensory and motor blockade.
• Nevertheless, except for body weight (less CSF in subjects with high
body mass index [BMI]), the volume of CSF does not correlate with
other anthropomorphic measurements available clinically.

38. 3. EPIDURAL SPACE
• Hogan’s study of frozen cryomicrotome cadaver sections suggests that
the epidural space is more segmented and less uniform.
• Fluoroscopic studies have demonstrated the presence of septa or
connective tissue bands within the epidural space, possibly explaining
the occasional one-sided epidural block
• This lack of uniformity also extends to age-related differences.
• There is evidence that adipose tissue in the epidural space diminishes
with age,and this effects changes in epidural dose requirements.

39. EPIDURAL BLOCK
• Thoracic epidural blocks are technically
more difficult to accomplish than are
lumbar blocks because of greater
angulation and the overlapping of the
spinous processes at the vertebral level

40. SCOLIOSIS
• The diagnosis of scoliosis is made when there is a Cobb angle of greater
than 10° in the coronal plane of the spine in a skeletally mature patient.
• A compensatory curvature of the spine always occurs in the opposite
direction of the scoliotic curve.

41. • In the patients with scoliosis, the vertebral body rotates toward the convex
side of the curve.
• As a result of this rotation, the spinous processes point toward the midline
(the concave side).
• This results in a larger interlaminar space on the convex side of the spine.
• A direct path to the neuraxial space is created by this vertebral body rotation,
allowing the use of a paramedian approach from the convex side of the
curve.
• X-rays, and most recently preprocedural ultrasound scanning, may be useful
to determine the longitudinal angulation of the spine, the location and
orientation of the spinous process, as well as the depth of the lamina.

43. STRUCTURES PIERCED WHILE GIVING SUBARACHNOID BLOCK

44. THANK YOU