3. The Nervous System is conventionally divided into
three major parts:
1.1. Central nervous system (CNS),Central nervous system (CNS),
2.2. Peripheral nervous system (PNS)Peripheral nervous system (PNS)
3.3. Autonomic nervous system (ANS)Autonomic nervous system (ANS)
The three component parts act in concert in the
overall control and integration of the motor, sensory,
and behavioral activities of the organism.
4. The methodologic creativity and observational
acumen of anatomists, physiologists, psycholo-
gists, and physicians have been impressive &
rewarding, but their work is far from finished.
(Functional Neuroanatomy: Text and Atlas, 2nd ed)
Adel K. Afifi M.D., M.S.
Ronald A. Bergman Ph.D.
11. The autonomic nervous system (ANS) is the
part of the nervous system concerned with
the innervation of involuntary structuresinnervation of involuntary structures,
such as:
• Heart
• smooth muscles
• glands.
It is distributed throughout the central and
peripheral nervous systems.
12. The ANS is dividedThe ANS is divided
into two parts:into two parts:
1.1. SympatheticSympathetic
(Thoracolumbar)
2.2. ParasympatheticParasympathetic
(Craniosacral)
In both parts, there areIn both parts, there are::
• Afferent nerve fibers
• Efferent nerve fibers.
• Preganglionic fibers
• Postganglionic fibers
3.3. Enteric divisionEnteric division
(Myenteric &
Submucosal
Plexuses)
13. Theses ganglia from up downwards:
1.Ciliary ganglion 2. Pterygopalatine ganglion
3. Submandibular ganglion 4. Otic ganglion
14. Continuous red = pregang. Sympathetic fibers
Dotted red = postganglionic Sympathetic fibers
Cotinuous blue = preganglionic parasympathetic fibers
Dotted blue = postganglionic parasympatheticfibers
15. Continuous red = preganglionic. Sympathetic fibers
Dotted red = postganglionic Sympathetic fibers
Cotinuous blue = preganglionic parasympathetic fibers
Dotted blue = postganglionic parasympatheticfibers
16. Functions:Functions:
1. Sympathetic activity prepare the body for an
emergency.
2. Parasympathetic activity are aimed at
conserving and restoring energy.
3. It has been suggested that while the enteric
plexuses can coordinate the activities of the gut
wall, the parasympathetic and sympathetic
inputs modulate these activities.
18. the vertebral caNal
Smooth-walled tubular,
space formed by series
of vertebral foramina lying
one above the other, ends
in sacral canal.
• AnteriorlyAnteriorly :
1. Bodies of the vertebrae,
2. Intervertebral discs,
3. Post. longitudinal ligament.
• Posteriorly:Posteriorly:
1. Vertebral laminae,
2. Ligamenta flava,
• At the sides:At the sides:
1. Pedicles of the vertebrae
2. Intervertebral foramina.
19. Vertebral Canal contains:Vertebral Canal contains:
1.spinal meninges
2.spinal cord with its nerve
roots and their vessles.
3.epidural space (extradural
space) which contains:
• loose connective tissue,
• fat
• Veins (Internal vertebral
venous plexus “IVVP” )
20. Internal Vertebral Venous Plexus (IVVP)Internal Vertebral Venous Plexus (IVVP)
• its throughout the canal
• Divided into :
1.1. Two anterior plexeses:Two anterior plexeses:
• Two longitudenal channels
• Lie on deep surface of
vertebral bodies
• On sides of posterior
longitudenal ligament.
2. Two posterior plexeses:Two posterior plexeses:
• Two longitudenal channels
• Lie on deep surface of
Laminae and ligamenta flava
21. • Both anterior and
posterior IVVPs are
united together by the
Transverse PlexesTransverse Plexes
opposite the laminae
• IVVPs receives the
BasiverTeBral veinsBasiverTeBral veins,
which are large veins
draining the draining
the active red marrow
in the bodies of the
vertebrae
22. • The IVVPs connected
through intervertebral
foraminae with the body
wall veins :
1.1. Vertebral veins,Vertebral veins,
2.2. Posterior intercostalPosterior intercostal
veins,veins,
3.3. Lumbar veinsLumbar veins
4.4. Lateral sacral veinsLateral sacral veins
23. Clinical points about IVVPs:Clinical points about IVVPs:
• provides a venous bypass of the diaphragmvenous bypass of the diaphragm. It
functions when the inferior vena cava cannot
cope with a sudden flush of blood resulting
from a sudden increase of intra-abdominal
pressure (e.g. in coughing or abdominal
straining), Thus pelvic and abdominal venous
blood is moment-arily squirted up the plexus
above diaphragm, into posterior intercostal
veins, and thereby into the superior vena cava.
• Thus its implicated in the spread of some pelvicspread of some pelvic
tumorstumors e.g. of the prostate to vertebral bodies,
and even to the skull without tumors having to
pass through the lungs.
25. Meninges of Spinal Cord:
• Three membranous layers of
connective tissue that protects
spinal cord.
• Damage or infection meninges,
such as in meningitis, can
cause serious neurological
damage and even death.
• Consisting of :
1. Dura mater (outer)
2. Arachnoid mater (intermediate)
3. Pia mater (inner)
26. A.P i a M a t e r:
has 2 layers:
• Intima Pia (InnerIntima Pia (Inner
Membranous LayerMembranous Layer):):
• Is intimately adherent to
the surface of the spinal
cord
• It is prolonged over the
spinal nerve roots until
where the dura blendsblends
with the epineuriumwith the epineurium of
the mixed spinal nerves.
27. 2.2. Epipia (Outer Vascular
Layer)
• Carries blood vessels that
supply and drain the spinal
cord.
• Supports spinal cord by:
A. Denticulate LigamentDenticulate Ligament ::
Flat bands attaches to
dura by 21 bands
B. Filum terminale:Filum terminale:
A filament fuses conus
medullaris to the end
of dural sac.
28. B. A r a ch n o i d
M a t e r
• Delicate impermeable
membrane
• Lies between pia and
dura
• Send many delicate
processes across the
subarachnoid space
to the pia mater,
forming a lace-like
arrangement.
29. Subdural space
is a very narrow
(microscopic)
space.
Subarachnoid space
is a wide which is
filled with CSF
30. C. D u r a M a t e r
• A dense, strong,
fibrous membrane
• Encloses the spinal
cord and cauda equina
Level Of Foramen Magnum:
• Attached firmly at the margin
of foramen magnum.
• Continues with the meningeal
layer of dura of brain.
31. In Vertebral Canal
(V.C.):
• Lies loosely in the V.C.,
Separated from its walls
by the extradural space.
• Extends down to the level
of the S1 and S2
• Below the site of spinal
cord termination (conus
medullaris), forms a sac
filled with CSF.
32. • Spinal Dura: also ensheathes:
1. dorsal roots
2. ventral roots,
3. dorsal root ganglia,
4. proximal portions
of spinal nerves,
• Spinal dura then
continues with the
epineurium of spinal
nerves at level of
the intervertebral
foramen.
33. Lumbar puncture
• Needle is inserted
between the spines of
L3-L4 or L4-L5
vertebrae
• Then penetrates the
dura to subarachnoid
CSF that is sampled.
• Since the spinal cord
ends at the level of
L1 vertebra, so there
is no danger
34. Spinal anaesthesia
• the anaesthetic
solution is injected
into the subarach-
noid space
• Also in space
between L3-L4 or
L4-L5
35. Epidural anaesthesia
the solution is
injected at
• any level into the
epidural (extradural)
space
• without penetrating
the dura,
• solution infiltrates
through the
meningeal sheaths
containing the nerve
roots
37. Definition:
The thick, whitish cord of
nerve tissue (a part of
CNS) that extends from the
medulla oblongata down
through the vertebral
column and from which the
spinal nerves branch off,
that convey motor and
sensory impulses to and
from various parts of the
body.
38. Gross Appearance of the Spinal Cord
LOCATION:
• Begins/
At foramen magnumforamen magnum
in the skull where
it continues with
medulla oblongatamedulla oblongata
39. IN ADULTS SpINAL corD
eNDS AT:
1.1. As becomes conus medull-As becomes conus medull-
arisaris at the level of the discdisc
between L1 - L2 bodiesbetween L1 - L2 bodies.
2. A level little above elbowabove elbow,
when arm by the side.
3. At TranspyloricTranspyloric level
40. • Thus, spinal cord lies in
upper 2/3 of the vertebralupper 2/3 of the vertebral
canalcanal
• At birth & young child, it
is longer & usually ends
at the lower border of L2
or upper border of the L3upper border of the L3
41. Spinal Cord Shape:
• Roughly CylindericalCylinderical
• Cervical EnlargementCervical Enlargement (C5- T1)
due to giving origin to Brachial
Plexus.
• Lumbar EnlargementLumbar Enlargement (L2- S3)
due to giving origin to
Lumbosacral Plexus.
• Bottum called Conus MedullarisConus Medullaris
• Filum terminaleFilum terminale is prolongation of
pia mater, attaches Conus to
back of coccyx.
• Cauda equinaCauda equina is lumbosacral
roots around the filum
terminale.
42.
43. Along the entire length of
the spinal cord, 31 pairs31 pairs
of spinalof spinal nervesnerves are
attached to it by:
1. Anterior (Motor) roots
2. Posterior (Sensory) roots
• Each root is attached to
the cord by a series of
rootlets that extend along
whole length of spinal
cord segment.
• Each posterior root have
a posterior root ganglion
46. External Features that
underlie pia mater are
1.1. Ventral (Anterior)Ventral (Anterior)
Median FissureMedian Fissure ::
• its deep
• underlies the
anterior spinal
artery
47. 2.2. Dorsal (Posterior)Dorsal (Posterior)
Median Sulcus:Median Sulcus:
• Its shallow
• Continuous with
dorsal median
septum
48. 3. Ventrolateral Sulcus:3. Ventrolateral Sulcus:
• Shallow
• Ventral rootlets
emerge here
4.4. DorsolateralSulcus:DorsolateralSulcus:
• ShallowShallow
• Dorsal rootletsDorsal rootlets
enter hereenter here
49. 5.5. Dorsal IntermediateDorsal Intermediate
Sulcus:Sulcus:
• Shallow grooveShallow groove
• Continuous with dorsalContinuous with dorsal
intermediate septumintermediate septum
• Between dorsal lateral &Between dorsal lateral &
dorsal median sulcidorsal median sulci
• Separates fasciculusSeparates fasciculus
gracilis from fasciculusgracilis from fasciculus
cuneatuscuneatus
52. Gray Matter
• As in other regions of
C.N.S, the gray matter
of the spinal cord
consists of a mixture
of :
1. Nerve cells (Neurons)
and their processes,
2. Neuroglia,
3. Blood vessels.
53. Gray Matter of Spinal Cord
• H-shaped in cross section.
Consist of :
1. Anterior gray columnAnterior gray column
2. Posterior gray columnPosterior gray column
3. Gray commissureGray commissure ::
containing the small
central canal, it unites
both above columns.
4. Lateral gray columnLateral gray column ::
is present in thoracic
& upper lumbar seg-
ments of the cord.
54. • Amount of gray
matter present at
any level of spinal
cord is related to
amount of muscle
innervated.
• Thus, its size is
greatest within the
cervIcAL and
LUmboSAcrA
L enlargements of
the cord, which
inner-vate the
muscles of the
upper and lower
limbs, respectively.
55. A. Nerve Cell Groups in
Anterior Gray Columns:
1. Medial group:
• present in most
segments
• innervating
skeletal muscles
of the neck and
trunk.
56. 2. Central group:
• smallest group
• present in some cervical
and lumbosacral segments.
• In C3-5, some neurons
innervate the diaphragm
and are referred to as:
phrenic nucleus.
• In C1-C6, some of cells
innervate trapezius and
sternocleidomastoid
muscles and are called :
accessory nucleus. The
axons of these cells form
the spinalpart o f the
accesso ry nerve.
57. 3.Lateral group:
• present in the
cervical and
lumbosacral
segments of the
cord
• responsible for
innervating the
skeletal muscles
of the upper and
lower limbs
respectively.
58. ANT. GRAY HORN CELLS
GROUP MEDIAL CENTRAL LATERAL
LOCATION ALL SEGMENTS
SOME CERVICAL &
LUMBOSACRAL
SEGMENTS
CERVICAL &
LUMBOSACRAL
SEGMENTS
TARGET
SKELETAL Ms.
OF NECK & TRUNK
DIAPHRAGM,
TRAPEZIUS,
&SCM
SKELETAL Ms. OF
UPPER & LOWER
LIMBS
OTHERS /
PHRENIC N,
SP. ACCESSORY N.
/
SUMMARY………..
59. B. Nerve Cell Groups in the
Posterior Gray Columns
• Substantia gelatinosa group:
• At apex of posterior gray column
• Present in all Levels of the spinal
cord.
• receives afferent fibers from
posterior rootposterior root concerned with:
a. pain,
b. temperature,
c. touch
• Receive descending fibers from
supraspinal levelssupraspinal levels.
60. 2. Nucleus proprius:
• situated anterior to the
substantia gelatinosa
• In all levels of spinal cord.
• receives fibers from the
posterior white columnposterior white column that
are associated with:
senses of position and
movement (proprioception),
two-point discrimination,
and vibration.
61. 3. Nucleus dorsalis
(Clarke's column)
• situated at the base of
posterior gray column
• extending from the C8-L3
( L4).
• associated with proprio-
ceptive endings (neuro-
muscular spindles and
tendon spindles).
62. 4. Visceral afferent nucleus
• situated lateral to the nucleus
dorsalis;
• it extends from the T1- L3 of
the spinal cord.
• It is associated with receiving
visceral afferent information.
63. POST. GRAY HORN CELLS
NUCLEUS
Substantia
gelatinosa
Nucleus
proprius
Nucleus
dorsalis
(Clarke's
column)
Visceral
afferent
nucleus
LOCATION All All
C8-L3
( L4)
T1- L3
RECIEVES
SENSTION
OF
1. pain,
2. temperature
3. touch
4. Some
descending
tracts
1. Position &
movement
(propriocept
ion),
2. two point
discriminati
on
3. vibration.
N.M.
spindles
and
tendon
spindles
visceral
afferent
information
SUMMARY………..
64. 3. Nerve Cell Groups in the
Lateral Gray Columns
• The intermediolateral
group of cells
• Cells are small
• T1-L3 (L4): give rise to
preganglionic sympathetic
fibers.
• S2-S4 : give rise to
preganglionic parasymp-
athetic fibers
65. 4. Gray Commissure & Central Canal
• Connecting anterior &
posterior gray horns
• In the center of the gray
commissure is situated the
central canal.
• The part posterior to the
central canal is often
referred to as the po sterio rpo sterio r
gray co mmissuregray co mmissure;
• But that anterior to the
canal is called the anterio ranterio r
gray co mmissuregray co mmissure.
66. Central canal:
• Throughout spinal segments
• Superiorly, it is continuous
with cavity of the fourth
ventricle.
• Inferiorly in the conus
medullaris,
1. it expands into the
fusiform shaped
(terminal ventricle)
2. It is filled with
cerebrospinal fluid.
• Thus, the central canal is
closed inferiorly and opens
superiorly into the fourth
ventricle.
67. rexed laminae
• The cytoarchitecture of
various sizes or shapes of
neurons led Rexed to
propose another class-
fication based on 10 layers
(laminae).
• its useful as it is related
more to function
68. Blood Supply of Spinal Cord
A. Arteries of Spinal Cord
three small arteries:
1. Two posterior spinal
arteries
2. Anterior spinal artery.
3. Segmental spinal arteries
69. 1. Posterior Spinal Arteries
• The posterior spinal arteries
arise either:
a. directly from: vertebral
arteries inside the skull
b. indirectly from the:
posterior inferior
cerebellar arteries.
• The posterior spinal arteries
supply the posterior 1/3 of
70. 2. Anterior Spinal Artery
• Formed by the union of
two arteries, each of
which arises from the
vertebral artery
inside the skull.
• Runs within the anterior
median fissure.
• Branches from it supplysupply
anterior 2/3anterior 2/3 of the spinal
cord.
71. 3.Segmental Spinal Arte
are branches of arteries outside the
vertebral column :
1. deep cervical arteries,
2. Intercostal arteries,
3. lumbar arteries.
• each segmental spinal artery gives
rise to anterior and posterior
radicular arteriesradicular arteries that accompany
the anterior and posterior nerve
roots to the spinal cord.
72. great anterior medullary
artery of adamkiewicz,
• One large and important artery
• arises from the aorta in the
lower thoracic or upper lumbar
vertebral levels;
• Unilateral,
• In majority, enters the spinal
cord from the left side.
• The importance of this artery
lies in the fact that it may be
the major source of blood to
the lower 2/3 of the spinal
cord.
73. Veins of the Spinal Cord
• The veins of the spinal cord
drain into tortuous longitu-
dinal channels that comm-
unicate :
• Superiorly: In the skull with
the veins of the brain and
the venous sinuses.
• Inferiorly: They drain mainly
into the Internal vertebral
venous plexus.
