Surgery & anatomy of vertebral column and spinal nerves

Topographic anatomy and operative
surgery of the vertebral column, spinal
cord and its membranes
Topic III

Topographic anatomy of the vertebral
column, spinal cord and its membranes
Part I

Fig 1. The vertebral column viewed from the side. The five different regions are shown
and labelled.

VERTEBRAL COLUMN
The vertebral column is a vertical series of approximately
33 small bones (known as vertebrae), which are
separated by intervertebral discs.
The vertebral column has four main functions:
1. Protection – encloses and protects the spinal cord
within the spinal canal.
2. Support – carries the weight of the body above the
pelvis.
3. Axis – forms the central axis of the body.
4. Movement – has roles in both posture and movement.
Vertebral Structure
All vertebrae share a basic common structure. They
each consist of a vertebral body, situated anteriorly,
and a posterior vertebral arch.
I. Vertebral body
It is the weight-bearing component, and its size increases as
the vertebral column descends (having to
support increasing amounts of weight).
The superior and inferior aspects of the vertebral body are
lined with hyaline cartilage. Adjacent vertebral bodies
are separated by a fibrocartilginous intervertebral disc.
Fig 2 .The general
structure of a vertebrae.

II. Vertebral Arch
The vertebral arch refers to the lateral and posterior parts of the vertebrae.
With the vertebral body, the vertebral arch forms an enclosed hole, called
a vertebral foramen. The foramina of the all vertebrae line up to form
the vertebral canal, which encloses the spinal cord.
The vertebral arches have a number of bony prominences, which act
as attachment sites for muscles and ligaments:
1) Pedicles: there are two of these, one left and one right. They point
posteriorly, meeting the flatter lamina.
2) Lamina: the bone between the transverse and spinal processes.
3) Transverse processes: these extend laterally and posteriorly away from
the pedicles. In the thoracic vertebrae, the transverse processes articulate
with the ribs.
4) Articular processes: at the junction of the lamina and the
pedicles, superior and inferior processes arise. These articulate with the
articular processes of the vertebrae above and below.
5) Spinous processes: posterior and inferior projection of bone, a site of
attachment for muscles and ligaments.

Fig 3. Superior view of a lumbar vertebrae

Cervical Vertebrae
There are seven cervical vertebrae in
the human body. They have three
main distinguishing features:
1. The spinous process bifurcates into
two parts, and so is known as a bifid
spinous process.
2. There are two transverse foramina,
one in each transverse process.
These conduct the vertebral arteries.
3. The vertebral foramen
is triangular in shape
There are some cervical vertebrae that
are unique. C1 and C2 (called the atlas
and axis respectively), are specialised
to allow for the movement of the
head.
The C7 vertebrae has a much longer
spinous process, which does not
bifurcate

Thoracic Vertebrae
The twelve thoracic vertebrae are medium-sized, and increase in size as
they move down the back. Their main function is to articulate with ribs,
producing the bony thorax.
Each thoracic vertebrae has two ‘demi facets‘ on each side of its vertebral
body. These articulate with the head of the respective rib, and the rib
inferior to it. On the transverse processes of the thoracic vertebrae there is
a costal facet for articulation with its respective rib.
The spinous processes are slanted inferiorly and anteriorly. This offers
increased protection to the spinal cord, preventing an object like a knife
entering the spinal canal through the intervertebral discs. In contrast to the
cervical vertebrae, the vertebral foramen is circular.
Lumbar Vertebrae
These are the largest of the vertebrae, of which there are five. They act to
support the weight of the upper body, and have various specializations to
enable them do this.
Lumbar vertebrae have very large vertebral bodies, which are kidney-
shaped. They lack the characteristic features of other vertebrae, with no
transverse foramina, costal facets, or bifid spinous processes.
However, like the cervical vertebral, they have a triangular shaped vertebral
foramen.

The sacrum is a collection of
five fused vertebrae. It is
described as an upside down
triangle, with the apex pointing
inferiorly. On the lateral walls of
the sacrum are facets, for
articulation with the pelvis at the
sacroiliac joints.
The coccyx is a small bone, which
articulates with the apex of the
sacrum. It is recognised by its
lack of vertebral arches. Due to
the lack of vertebral arches, there
is no vertebral canal, and so the
coccyx does not transmit the
spinal cord.

JOINTS
Each vertebra has five articulations. The vertebral bodies indirectly articulate
with each other, and the articular processes also form joints.
The vertebral body joints are cartilaginous joints, designed for weight-
bearing. The articular surfaces are covered by hyaline cartilage, and are
connected by a fibrocartilage intervertebral disc.
There are two ligaments that strengthen these joints; the anterior and posterior
longitudinal ligaments. The anterior longitudinal ligament is thick and
prevents hyperextension of the vertebral column. The posterior longitudinal
ligament is weaker and prevents hyperflexion.
The joints between the articular facets are called facet joints. These allow for
some gliding motions between the vertebrae. They are strengthened by
various ligaments:
A. Ligamentum Flavum: extends from lamina to lamina.
B. Interspinous and Supraspinous ligaments: these join the spinous
processes together. The interspinous ligaments attach between processes,
and the supraspinous ligaments attach to the tips.
C. Intertransverse ligaments: extends between transverse processes.

MUSCLES
The muscles of the back can be divided into three groups – superficial,
intermediate and intrinsic:
1. Superficial – associated with movements of the shoulder.
2. Intermediate – associated with movements of the thoracic cage.
3. Deep – associated with movements of the vertebrae column.
The deep muscles develop embryologically in the back, and are thus described
as intrinsic muscles. The superficial and intermediate muscles do not develop
in the back, and are classified as extrinsic muscles.
I. The superficial back muscles are situated underneath the skin and superficial
fascia. They originate from the vertebral column and attach to the bones of the
bones of the sholder – the clavicle, scapula and humerus. All these muscles
are therefore associated with movements of the upper limb.
The muscles in this group are the trapezius, latissimus dorsi, levator scapulae
and the rhomboids. The trapezius and the latissimus dorsi lie the most
superficially, with the trapezius covering the rhomboids and levator scapulae.

1. The trapezius is a broad, flat and triangular muscle. The muscles on each
side form a trapezoid shape. It is the most superficial of all the back muscles.
Attachments: originates from the skull, ligamentum nuchae and the spinous processes of
C7-T12. The fibres attach to the clavicle, acromion and the scapula spine.
Innervation: motor innervation is from the accessory nerve. It also receives
proprioceptor fibres from C3 and C4 spinal nerves.
Actions: the upper fibres of the trapezius elevates the scapula and rotates it during
abduction of the arm. The middle fibres retract the scapula and the lower fibres pull the
scapula inferiorly.
2. The latissimus dorsi originates from the lower part of the back, where it
covers a wide area.
Attachments: has a broad origin – arising from the spinous processes of T6-T12, iliac
crest, thoracolumbar fascia and the inferior three ribs. The fibres converge into a tendon
that attaches to the intertubercular sulcus of the humerus.
Innervation: thoracodorsal nerve.
Actions: extends, adducts and medially rotates the upper limb.

3. Levator Scapulae is a small strap-like muscle. It begins in the neck, and
descends to attach to the scapula.
Attachments: originates from the transverse processes of the C1-C4 vertebrae and
attaches to the medial border of the scapula.
Innervation: dorsal scapular nerve.
Actions: elevates the scapula.
4. Rhomboids
There are two rhomboid muscles – major and minor. The rhomboid minor is situated
superiorly to the major.
A. Rhomboid Major
Attachments: originates from the spinous processes of T2-T5 vertebrae. Attaches to the
medial border of the scapula, between the scapula spine and inferior angle.
Actions: retracts and rotates the scapula.
B. Rhomboid Minor
Attachments: originates from the spinous processes of C7-T1 vertebrae. Attaches to the
medial border of the scapula, at the level of the spine of scapula.
Actions: retracts and rotates the scapula

Fig 4. The superficial
muscles of the back

II. The intermediate group contains two muscles – the serratus
posterior superior and serratus posterior inferior. These muscles run
from the vertebral column to the ribcage, and assist with elevating and
depressing the ribs. They are thought to have a slight respiratory
function.
1. The serratus posterior superior is a thin, rectangular shaped muscle.
It lies deep to the rhomboid muscles on the upper back.
Attachments: originates from the lower part of the ligamentum nuchae,
and the cervical and thoracic spines (usually C7 – T3). The fibres pass in
an inferolateral direction, attaching to ribs 2-5.
Innervation: intercostal nerves.
Actions: elevates ribs 2-5.
2. The serratus posterior inferior is broad and strong. It lies
underneath the latissimus dorsi.
Attachments: originates from the thoracic and lumbar spines (usually T11
– L3). The fibres pass in a superolateral direction, attaching to ribs 9-12.
Innervation: intercostal nerves.
Actions: depresses ribs 9-12.

Fig 5. The serratus posterior inferior.

III. The deep muscles of the back are well-developed, and collectively extend
from the sacrum to the base of the skull. They are associated with the movements of the
vertebral column, and the control of posture.
The muscles themselves are covered by deep fascia, which plays a key role in their
organisation.
Anatomically, the deep back muscles can be divided into three layers :
1. The superficial muscles are also known as the spinotransversales. There are two
muscles in this group – splenius capitis and splenius cervicis. They are both
associated with movements of the head and neck.
They are located on the posterolateral aspect of the neck, covering the deeper neck muscles.
a) Splenius Capitis
Attachments: Originates from the lower aspect of the ligamentum nuchae, and the spinous
processes of C7 – T3/4 vertebrae. The fibres ascend, attaching to the mastoid process
and the occipital bone of the skull.
Innervation: Posterior rami of spinal nerves C3 and C4.
Actions: Rotate head to the same side.
b) Splenius Cervicis
Attachments: Originates from the spinous processes of T3-T6 vertebae. The fibres ascend,
attaching to the transverse processes of C1-3/4.
Innervation: Posterior rami of the lower cervical spinal nerves.
Actions: Rotate head to the same side.
!!! The two splenius muscles can also act together to extend the head and neck.

Fig 6. The splenius muscles, located with the superficial layer of intrinsic back muscles.

2. There are three intermediate intrinsic back muscles – the iliocostalis, longissimus
and spinalis. Together these muscles form a column, known as the erector spinae.
The erector spinae is situated posterolaterally to spinal column, between the vertebral
spinous processes and the costal angle of the ribs.
All three muscles can be subdivided by their superior attachments (into lumborum, thoracic,
cervicis and capitis). They also all have a common tendinous origin, which arises from:
 Lumbar and lower thoracic vertebrae.
 Sacrum.
 Posterior aspect of iliac crest.
 Sacroiliac and supraspinous ligaments
1) The iliocostalis muscle is located laterally within the erector spinae. It is associated
with the ribs, and can be divided into three parts – lumborum, thoracis, and
cervicis.
Attachments: Arises from the common tendinous origin, and attaches to the costal angle of
the ribs and the cervical transverse processes.
Innervation: Posterior rami of the spinal nerves.
Actions: Acts unilaterally to laterally flex the vertebral column. Acts bilaterally to extend the
vertebral column and head.
2) Longissimus is situated between the iliocostalis and spinalis. It is the largest of the
three columns. It can be divided into three parts – thoracic, cervicis and capitis.
Attachments: Arises from the common tendinous origin, and attaches to the lower ribs, the
transverse processes of C2 – T12, and the mastoid process of the skull.
Actions: Acts unilaterally to laterally flex the vertebral column. Acts bilaterally to extend the
vertebral column and head.

3) Spinalis is located medially within the erector spinae. It is the smallest of the
three muscle columns. It can be divided into the thoracic, cervicis and capitis (although
the cervicis part is absent in some individuals).
Attachments: Arises from the common tendinous origin, and attaches to the spinous
processes of C2, T1-T8 and the occipital bone of the skull.
Actions: Acts unilaterally to laterally flex the vertebral column. Acts bilaterally to extend
the vertebral column and head
3. The deep intrinsic muscles are located underneath the erector spinae. They are a
group of short muscles, associated with the transverse and spinous processes of the
vertebral column.
 There are three major deep intrinsic muscles in this group – the semispinalis,
multifidus and rotatores.
1. The semispinalis is the most superficial of the deep intrinsic muscles. Much like the
intermediate muscles, it can be divided by its superior attachments into thoracic, cervicis
and capitis.
Attachments: originates from the transverse processes of C4-T10. The fibres ascend 4-6
vertebral segments, attaching to the spinous processes of C2-T4, and to the occipital
bone of the skull.
Innervation: posterior rami of the spinal nerves.
Actions: extends and contralaterally rotates the head and vertebral column.

2. Multifidus is located underneath the semispinalis muscle. It is best developed in the
lumbar area.
Attachments: has a broad origin – arises from the sacrum, posterior iliac spine, common
tendinous origin of the erector spinae, mamillary processes of lumbar vertebrae,
transverse processes of T1-T3 and articular processes of C4-C7. The fibres ascend 2-4
vertebral segments, attaching the spinous processes of the vertebrae.
Actions: stablises the vertebral column.
3. Rotatores
The rotatores are most prominent in the thoracic region
Attachments: originates from the vertebral transverse processes. The fibres ascend, and
attach to the lamina and spinous processes of the immediately superior vertebrae.
Actions: stablises the vertebral column, and has a proprioceptive function.
 Minor Deep Intrinsic Muscles:
1. Interspinales: Spans between adjacent spinous processes. Acts to stablise the vertebral
column.
2. Intertranversari – Spans between adjacent transverse processes. Acts to stablise the
vertebral column.
3. Levatores costarum – Originates from the transverse processes of C7-T11, and
attaches to the rib immediately below. Acts to elevate the ribs

Fig 8. The semispinalis
and multfidus muscles.

THE SPINAL CORD
The spinal cord is a tubular bundle of nervous tissue and supporting cells that extends from
the brainstem to the lumbar vertebrae. Together, the spinal cord and the brain form the
central nervous system.
The spinal cord is a cylindrical structure, greyish-white in colour. It has a relatively simple
anatomical course:
 The spinal cord arises cranially as a continuation of the medulla oblongata (part of the
brainstem).
 It then travels inferiorly within the vertebral canal, surrounded by the spinal meninges
containing cerebrospinal fluid.
 At the L2 vertebral level the spinal cord tapers off, forming the conus medullaris.
As a result of the termination of the spinal cord at L2, it occupies around two thirds of the
vertebral canal. The spinal nerves that arise from the end of the spinal cord are bundled
together, forming a structure known as the cauda equina.
During the course of the spinal cord, there are two points of enlargement. The cervical
enlargement is located proximally, at the C4-T1 level. It represents the origin of the
brachial plexus. Between T11 and S1 is the lumbar enlargement, representing the origin
of the lumbar and sacral plexus.
The spinal cord is marked by two depressions on its surface. The anterior median fissure is
a deep groove extending the length of the anterior surface of the spinal cord. On the
posterior aspect there is a slightly shallower depression – the posterior median sulcus.

Fig 9. The external structure of the
spinal cord.
Fig 10. The expanded sub-arachnoid space,
forming the lumbar cistern.

THE SPINAL MENINGES
The spinal meninges are three membranes that surround the spinal cord – the dura mater,
arachnoid mater, and pia mater. They contain cerebrospinal fluid, acting to support and
protect the spinal cord. They are analogous with the cranial meninges.
Distally, the meninges form a strand of fibrous tissue, the filum terminale, which attaches to
the vertebral bodies of the coccyx. It acts as an anchor for the spinal cord and meninges.
1) Dura Mater is the most external of the meninges. It extends from the foramen
magnum to the filum terminale, separated from the walls of the vertebral canal by
the epidural space. This space contains some loose connective tissue, and the internal
vertebral venous plexus. As the spinal nerves exit the vertebral canal, they pierce the dura
mater, temporarily passing in the epidural space. In doing so, the dura mater surrounds the
nerve root, and fuses with the outer connective tissue covering of the nerve,
the epineurium.
2) Arachnoid Mater is a delicate membrane, located between the dura mater and the pia
mater. It is separated from the latter by the subarachnoid space, which contains
cerebrospinal fluid. Distal to the conus medullaris, the subarachnoid space expands,
forming the lumbar cistern. This space accessed during a lumbar puncture (to obtain
CSF fluid) and spinal anaesthesia.

3) Pia Mater is the innermost of the meninges. It is a thin membrane that covers the spinal
cord, nerve roots and their blood vessels. Inferiorly, the spinal pia mater fuses with
the filum terminale. Between the nerve roots, the pia mater thickens to form the
denticulate ligaments. These ligaments attach to the arachnoid mater, suspending the
spinal cord in the vertebral canal.
The spinal nerves are mixed nerves that originate from the spinal cord, forming the
peripheral nervous system.
Each spinal nerve begins as an anterior (motor) and a posterior (sensory) nerve root. These
roots arise from the spinal cord, and unite at the intervertebral foramina, forming a
single spinal nerve.
The spinal nerve then leaves the vertebral canal via the intervertebral foramina, and then
divides into two:
A. Posterior rami – supplies nerve fibres to the synovial joints of the vertebral column,
deep muscles of the back, and the overlying skin.
B. Anterior rami – supplies nerve fibres to much of the remaining area of the body, both
motor and sensory.
The nerve roots L2-S5 arise from the distal end of the spinal cord, forming a bundle of
nerves known as the cauda equina.

Fig 11. The origin of the spinal nerves from the spinal cord.

The spinal cord is primarily supplied by three longitudinal arteries, as
it descends from the brainstem to the conus medullaris. These are:
1. Anterior spinal artery– formed from branches of the vertebral
arteries, travelling in the anterior median fissure. Gives rise to the
sulcal arteries, which enter the spinal cord.
2. Two posterior spinal arteries– originate from the vertebral artery or
the posteroinferior cerebellar artery, anastomosing with one another in
the pia mater.
However, below the cervical level supply from these longitudinal arteries
is insufficient. There is support via anastomosis with the segmental
medullary and radicular arteries.
The anterior and posterior segmental medullary arteries are derived
from spinal branches of a number of arteries, before entering the
vertebral canal through the intervertebral foramina.
The great anterior segmental artery of Adamkiewicz reinforces
circulation to the inferior 2/3 of the spinal cord, and is found on the left
in the majority of individuals.
The radicular arteries supply (and follow the path of) the anterior and
posterior nerve roots. Some radicular arteries may also contribute to
supplying the spinal cord.

The spinal cord is supplied by three anterior and three posterior spinal veins.
These veins are valveless, and form an anastamotic network along the surface
of the spinal cord. They also receive venous blood from the radicular veins.
The spinal veins drain into the internal and external vertebral plexuses, which in
turn empty into the systemic segmental veins. The internal vertebral
plexus also empties into the dural venous sinuses superiorly.
Fig 12. The external and internal vertebral venous plexuses.

Part II
Operative surgery of the vertebral
column, spinal cord and its membranes

LUMBAR PUNCTURE
Lumbar puncture (LP), also known as a spinal tap, is a medical procedure in which a
needle is inserted into the spinal canal, most commonly to collect cerebrospinal
fluid (CSF) for diagnostic testing, or very rarely as treatment ( “therapeutic lumbar
puncture”) to relieve increased intracranial pressure.
Lumbar puncture is a procedure that is often performed in the emergency department to
obtain information about the cerebrospinal fluid (CSF).Although usually used for
diagnostic purposes to rule out potential life-threatening conditions ( bacterial
meningitis or subarachnoid hemorrhage), it is also sometimes used for therapeutic
purposes (treatment of pseudotumor cerebri). CSF fluid analysis can also aid in the
diagnosis of various other conditions (demyelinating diseases and carcinomatous
meningitis).
Lumbar puncture should be performed only after a neurologic examination but should
never delay potentially life-saving interventions, such as the administration of
antibiotics and steroids to patients with suspected bacterial meningitis.

Illustration depicting common positions for lumbar puncture procedure.

Technique:
1. Position the patient in the bed. Generally, the lateral decubitus position
is preferred. Arch the patient’s back towards you.
2. Identify and mark anatomic landmarks. The L4 spinous process is at
the level of the posterior – superior iliac crests.
3. Prepare the skin with antiseptic solution . Apply a circular motion
with a gradually increasing circumference.
4. Apply the sterile drape.
5. Create a wheal with anesthetic in the skin overlying the entry site.
Then, infiltrate and anesthetize the deeper tissue.
6. Insert the needle in the midline. Hold the needle parallel to the bed,
and advance it toward the umbilicus. Remove the stylet periodically
to check for CSF.
7. CSF will flow from the needle hub when the subarachnoid space has
been penetrated.
8. Attach the manometer and measure the opening pressure.
9. Collect the CSF sample in sequential , numbered vials.
10. Replace the stylet before removing the needle.

EPIDURALANESTHESIA
Epidural anesthesia can be used as sole
anesthetic for procedures involving the lower
limbs, pelvis, perineum and lower abdomen. It
is possible to perform upper abdominal and
thoracic procedures under epidural anesthesia
alone, but the height of block required, with
its attendant side effects, make it difficult to
avoid significant patient discomfort and risk.
The advantage of epidural over spinal
anesthesia is the ability to maintain
continuous anesthesia after placement of an
epidural catheter, thus making it suitable for
procedures of long duration. This feature also
enables the use of this technique into the
postoperative period for analgesia, using
lower concentrations of local anesthetic drugs
or in combination with different agents.
Epidural space (extradural space) is localized
in spine canal between ligamenta flava and
dura mater. Contains loose connective tissue.
The pressure in epidural space is lower than
atmospherical pressure (will be useful).
Epidural space is 3–5 mm wide.

Positioning:
1. The sitting position is commonly employed. Instruct the patient rest his or her legs on a
step stool and hold a pillow. Instruct the patient to arch forward like an angry cat to
decrease lumbar lordosis.
2. The lateral decubitus position is another possible position.
3. The prone position is employed when epidural nerve block is used in chronic pain
management; fluoroscopy is usually required.
Lumbar level:
 Use the lumbar level of insertion for anesthesia and postoperative analgesia for lower
abdominal, pelvic, and lower extremity procedures.
 Start a peripheral intravenous line to administer fluids and medications.
 Position the patient in the seated or lateral decubitus position with the back arched to
minimize the lumbar lordosis.
 Prepare the back with povidone-iodine solution (eg, Betadine) and place a sterile drape.
Use chlorhexidine gluconate (Hibiclens) for patients who are allergic to povidone-iodine
solution.
 Palpate the spinous processes. The midline interlaminar approach is used in lumbar
regions because the spinous processes are less angulated in these regions.
 After the skin and subcutaneous tissues are anesthetized with local anesthetic, introduce
the Tuohy needle into the lower part of the interspace and advance for about 2-3 cm
until the needle is firmly placed in the interspace.

Instruments for epidural catheterization: philter, catheter, Tuohy needle and syringe.

 Attach the glass syringe (prefilled with air or saline 2 ml) to the needle and continue
advancing in slow increments, frequently checking for loss of resistance. A gentle tap
on the glass syringe piston is enough to determine the resistance. Sometimes, a small
bubble of air in the saline is helpful. The bubble compresses with every tap on the
piston.
 As the ligamentum flavum is reached, the resistance increases to a firm and gritty
feeling. Once the epidural space is reached, resistance is lost. When the piston is
gently tapped, it easily plunges in the syringe. The air bubble in the saline no longer
compresses, and saline is easily injected into the epidural space.
 Once the epidural space is reached, aspirate to rule out cerebrospinal fluid (CSF).
 If performing a single shot procedure, inject the medication and remove the needle.
 If placing a catheter, gently advance the catheter through the needle for about 4-5 cm
and then remove the needle.
 Connect a connector to the end of the catheter and remove the sterile drape.
 Secure the epidural catheter to the patient's back with sterile Tegaderm dressing, and
inject a test dose of medication. The test dose rules out intrathecal or intravascular
location of the catheter.
 With a successful neuraxial blockade, a zone of differential sympathetic nervous
system blockade typically occurs at the spinal level. The zone of differential motor
blockade may average up to 4 segments below the sensory level in epidural rather
than spinal blockade.

Thoracic level:
 At the low thoracic levels, the angulation of the spinous processes is
increased, and less interlaminar space is available. Greater access to the
epidural space is available when the paramedian approach is used; therefore,
the paramedian interlaminar approach is easier and desirable at low thoracic
levels.
 In the paramedian approach, insert the needle slightly to the side of the
midline and advance it straight until the lamina is reached.
 Subsequently, direct the needle in a cephalad and medial direction until it is
walked off the superior aspect of the lamina, then advance it toward the
ligamentum flavum, using the loss of resistance technique. Either air or saline
can be used to aid with the loss of resistance technique.
 The rest of the procedure is the same as described for the lumbar level above

Spine Surgery
In the open surgery or minimally invasive spine surgery (MISS) the spine can be
accessed from different directions. These are referred to as surgical approaches
and are explained below:
1. Anterior approach: as the name implies, the surgeon accesses the spine from the
front of body, through the abdomen.
2. Posterior approach: an incision is made in back.
3. Lateral approach: the pathway to your spine is made through side.
Common surgical procedures:
1. Discectomy or Microdiscectomy: removal of a herniated intervertebral disc.
Therefore, removing pressure from the compressed nerve.
2. Laminectomy: removal of the thin bony plate on the back of the vertebra called
the laminae to increase space within the spinal canal and relieve pressure.
3. Laminotomy: removal of a portion of the vertebral arch (lamina) that covers the
spinal cord. A laminotomy removes less bone than a laminectomy. Both
laminectomy and laminotomy are decompression procedures. “Decompression”
usually means tissue compressing a spinal nerve is removed.

4. Foraminotomy: removal of bone or tissue at/in the passageway (called
the neuroforamen) where nerve roots branch off the spinal cord and exit the spinal
column.
5. Disc replacement: as an alternative to fusion, the injured disc is replaced with an
artificial one.
6. Spinal fusion: a surgical technique used to join two vertebrae. Spinal fusion may
include the use of bone graft with or without instrumentation (eg, rods, screws).
There are different types of bone graft, such as own bone (autograft) and donor
bone (allograft). A fusion can be accomplished by different approaches:
a) Anterior Lumbar Interbody Fusion (ALIF)
b) Posterior Lumbar Interbody Fusion (PLIF)
c) Transforaminal Lumbar Interbody Fusion (TLIF) indicates a surgical
approach through the foramen.
d) Lateral Interbody Fusion (LIF) in which the minimally invasive approach
is from the side of the body.
ALIF, PLIF, TLIF, LIF: all pertain to lumbar interbody fusion used to stabilize the
spinal vertebrae and eliminate movement between the bones.

Herniated disc
Spinal herniated disc, also known as a slipped disc,
is a medical condition affecting the spine in which
a tear in the outer, fibrous ring of an intervertebral
disc allows the soft, central portion to bulge out
beyond the damaged outer rings.
Disc hernition is usually due to age-related
degeneration of the outer ring, known as the anulus
fibrosus, although trauma, lifting injuries, or
straining have been implicated as well. Tears are
almost always postero -lateral (on the back of the
sides) owing to the presence of the posterior
longitudinal ligament in the spinal canal. This tear
in the disc ring may result in the release of
chemicals causing inflammation, which may
directly cause severe pain even in the absence of
nerve root compression.
The majority of spinal disc herniation cases occur in
the lumbar region (95% in L4-L5 or L5-S1). The
second most common site is the cervical region
(C5-C6, C6-C7). Herniations usually occur
posterolaterally, where the anulus fibrosus is
relatively thin and is not reinforced by the posterior
or anterior longitudinal ligament

Cervical disc herniations occur in the neck, most often
between the fifth & sixth (C5/6) and the sixth and
seventh (C6/7) cervical vertebral bodies.
Symptoms can affect the back of the skull, the neck,
shoulder girdle, scapula, arm, and hand. The nerves of
the cervical plexus and brachial plexus can be
affected. Usually, a posterolateral disc hernia will affect
the nerve root exiting at the level of the disk. Nerves
roots are numbered according to the vertebral body
below them (except the C8 nerve root). Thus, a C5/6
disc hernia will normally affect the C6 nerve root.
Lumbar disc herniations occur in the lower back, most
often between the fourth and fifth (L4/ L5)lumbar
vertebral bodies or between the fifth and the sacrum.
Symptoms can affect the lower back, buttocks, thigh,
anal/ genital region (via the perineal nerve), and may
radiate into the foot and/or toe. The sciatic nerve is the
most commonly affected nerve, causing symptoms
of sciatica. The femoral nerve can also be affected and
cause the patient to experience a numb, tingling feeling
throughout one or both legs and even feet or even a
burning feeling in the hips and legs. A hernia in the
lumbar region often compresses the nerve root exiting
at the level below the disk. Thus, a herniation of the
L4/5 disc will compress the L5 nerve root.
Herniated
disc at C6-C7
level
Herniated
disc at L4-
L5 level

Lumbar Discectomy Technique:
1) Approach: open discectomy (with or without the use of an operating
microscope) or minimally invasive approach.
2) The proposed midline incision site is marked and the surgical field prepared and
draped. The incision site is infiltrated with 1% lidocaine mixed with 1:100,000
epinephrine. A midline skin incision is made with a scalpel №10 along the
previously marked incision. The dissection of the subcutaneous tissues is
completed using the monopolar electrocautery.
3) The subcutaneous tissues are retracted using self-retaining Weitlaner retractors.
The lumbodorsal fascia is then identified and opened along the spinous process
just off the midline using the monopolar electrocautery. At this stage, the
desired spinal level should be confirmed with intraoperative radiography.
4) The paraspinous muscles are stripped from the spinous processes using a
subperiosteal technique down along the lamina to the edge of the facets either
bluntly or with monopolar cautery. For a discectomy, exposure to the medial
edge of the facet joints is generally adequate. (Further lateral dissection can damage the
capsule of the facet joint and can potentially lead to instability at that level). The surgical level
can again be confirmed before proceeding with bony removal.
5) The microscope covered with sterile drapes is brought into the field at this
stage. The ligamentum flavum is detached from the inferior surface of the
lamina using an angled curette, and a hemilaminotomy is then performed using
the combination of the high-speed drill and Kerrison rongeurs.

6) The thecal sac, along with the nerve root, is then retracted medially, and the underlying
disc surface can be seen. The posterior longitudinal ligament and annulus fibrosus is
then cut using a scalpel №11 or 15. After cutting open the annulus, disc material may
begin to extrude and can be removed using pituitary forceps. (When placing the pituitary
into the disc space, care must be taken not to insert too deep in case of an incompetent
anterior longitudinal ligament that could result in injury to the iliac vessels. Up- and
down-angled curettes can be used to help release residual disc fragments or tamp down a
central disc bulge).
7) After the surgeon is satisfied that an adequate amount of disc has been removed, the
thecal sac and the nerve root is inspected for residual compression and CSF leak. Some
surgeons place steroids (40 mg of methylprednisolone acetate or 4 mg dexamethasone)
over the nerve root at this stage to decrease postsurgical inflammation. Placement of a
free fat graft over the thecal sac has also been attempted to prevent adhesion formation.
8) The fascial layer is closed using 2-0 Vicryl, which is important to prevent wound
breakdown. The skin layer is closed with a subcuticular 4-0 Monocryl.

Spinal stenosis
Spinal stenosis is a condition in which the spinal column narrows and starts
compressing the spinal cord. This process is typically gradual. If the narrowing
is minimal, no symptoms will occur. Too much narrowing can compress the
nerves and cause problems.
With spinal stenosis, the spinal canal is narrowed at the vertebral canal, which is
a foramen between the vertebrae where the spinal cord (in the cervical or
thoracic spine) or nerve roots (in the lumbar spine) pass through.
Stenosis can occur anywhere along the spine. There are several types of spinal
stenosis, with lumbar stenosis and cervical stenosis being the most frequent.
While lumbar spinal stenosis is more common, cervical spinal stenosis is more
dangerous because it involves compression of the spinal cord where as the
lumbar spinal stenosis involves compression of the cauda equina.
Several types of surgery are used to treat spinal stenosis:
1. Laminectomy is the most common type of surgery. A surgeon removes part of
the vertebrae to provide more room for the nerves.
2. Foraminotomy is a surgery that’s done to widen the part of the spine where
the nerves exit.
3. Spinal fusion is typically performed in more severe cases, especially when
multiple levels of the spine are involved, to prevent instability. Bone grafts or
metal implants are used to attach the affected bones of the spine together.

Scoliosis
Scoliosis is a medical condition in which a person's spine has a sideways curve.
The spine has normal curves (when looking from the side, but it should appear straight
when looking from the front):
1. Kyphosis is a curve in the spine seen from the side in which the spine is bent forward.
There is a normal kyphosis in the middle (thoracic) spine.
2. Lordosis is a curve seen from the side in which the spine is bent backward. There is a
normal lordosis in the upper (cervical) spine and the lower (lumbar) spine.
People with scoliosis develop additional curves to either side of the body, and the bones
of the spine twist on each other, forming a "C" or an "S" shape in the spine.
In most cases, the reasons for the change in shape are not known, but in other cases,
cerebral palsy, muscular dystrophy, and spina bifida are factors in the development of
scoliosis.
Surgery involves correcting the curve back to as close to normal as possible and
performing a spinal fusion to hold it in place.
In spinal fusion, surgeons connect two or more of the bones in the spine (vertebrae)
together, so they can't move independently. Pieces of bone or a bone-like material are
placed between the vertebrae. Metal rods, hooks, screws or wires typically hold that
part of the spine straight and still while the old and new bone material fuses together.

Surgery & anatomy of vertebral column and spinal nerves

Surgery & anatomy of vertebral column and spinal nerves

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