spinal cord anatomy blood supply and cross sections.with cord syndromes

1. Anatomy, Blood supply and
sections of Spinal Cord
Chair person
Dr Sadashivaiah G
Professor
Dept of Gen. Medicine
Presenter
Dr Amar Patil

2. contents
 Introduction
 Segmental and Longitudinal Organization
 Anatomy- cross section
 Internal Structure of the Spinal Cord
(laminae and nuclei)
 Blood supply of spinal cord.
 Ascending And Descending tracts.
 Cord syndromes.

3. Introduction
 The spinal cord is the most important structure
between the body and the brain. The spinal cord
extends from the foramen magnum where it is
continuous with the medulla to the level of the first or
second lumbar vertebrae.
 It is a vital link between the brain and the body, and
from the body to the brain.
 The spinal cord is 40 to 50 cm long and 1 cm to 1.5 cm
in diameter. Two consecutive rows of nerve roots
emerge on each of its sides. These nerve roots join
distally to form 31 pairs of spinal nerves.

4.  The spinal cord is a cylindrical structure of nervous
tissue composed of white and gray matter, is uniformly
organized and is divided into four regions: cervical (C),
thoracic (T), lumbar (L) and sacral (S)
 Although the spinal cord constitutes only about 2% of
the central nervous system (CNS), its functions are
vital. Knowledge of spinal cord functional anatomy
makes it possible to diagnose the nature and location of
cord damage and many cord diseases.

5. Spinal Cord
 Contained in epidural space
 Network of sensory and motor
nerves
 Firm, cord-like structure
• Extends from foramen
magnum to L1
• Terminates at the
conus medularis
• The cauda equina
begins below L1
• Filum terminale extends
from conus medularis to the
coccyx.

6. Segmental and Longitudinal Organization
 The spinal cord is divided into four
different regions: the cervical, thoracic,
lumbar and sacral regions .
 The different cord regions can be
visually distinguished from one another.
Two enlargements of the spinal cord can
be visualized:
-The cervical enlargement, which
extends between C3 to T2; and
-The lumbar enlargements which
extends between L1 to S3.

7.  The surface of the spinal cord shows several
longitudinal grooves:
- Deep anterior fissure
- Shallow posterior median sulcus
- Lateral aspect two sulci: antero-lateral and postero-
lateral.
 From the lateral sulci a series of root filaments emerge
anteroiorly and posteriorly on each side.
 Several filaments from antero-lateral and postero-
lateral sulcus unite to form ventral and dorsal root
respectively.
 The dorsal and ventral roots are paired, they join distal
to the dorsal root ganglion and form the spinal nerve
which exits the canal through the interverterbral
foramen.

8. Spinal Nerve Topography
 The cord is segmentally organized.
There are 31 segments, defined
by 31 pairs of nerves exiting the
cord. These nerves are divided
into 8 cervical, 12 thoracic, 5
lumbar, 5 sacral, and 1 coccygeal
nerve.
 Dorsal and ventral roots enter and
leave the vertebral column
respectively through
intervertebral foramen at the
vertebral segments corresponding
to the spinal segment.

9. Developmental anatomy
 During the initial third month of embryonic
development, the spinal cord extends the entire length
of the vertebral canal and both grow at about the same
rate.
 As development continues, the body and the vertebral
column continue to grow at a much greater rate than
the spinal cord proper. This results in displacement of
the lower parts of the spinal cord with relation to the
vertebrae column.

10. Developmental anatomy-cont
The outcome of this uneven growth is that the adult
spinal cord extends to the level of the first or second
lumbar vertebrae, and the nerves grow to exit
through the same intervertebral foramina as they did
during embryonic development.
 This growth of the nerve roots occurring within the
vertebral canal, results in the lumbar, sacral, and
coccygeal roots extending to their appropriate
vertebral levels.

11.  All spinal nerves, except the first, exit below their
corresponding vertebrae. In the cervical segments,
there are 7 cervical vertebrae and 8 cervical nerves .
 C1-C7 nerves exit above their vertebrae whereas the C8
nerve exits below the C7 vertebra. It leaves between
the C7 vertebra and the first thoracic vertebra.
Therefore, each subsequent nerve leaves the cord
below the corresponding vertebra.

12.  Therefore, the root filaments of spinal cord segments
have to travel longer distances to reach the
corresponding intervertebral foramen from which the
spinal nerves emerge.
 The lumbosacral roots are known as the cauda equina

13. Cord level Vertebral body
C8 C7
T5 T2-3
T12 T-10
L1-2 T11
L3-4 T12
L5 L1
S1-S5 L2

14. Functions of the Spine
Protection of
 spinal cord and nerve
roots
• internal organs

15. Functions of the Spine
 Flexibility of motion in six degrees of freedom
Left and Right
Side Bending
Flexion and Extension
Left and Right
Rotation

16. Cervical Lordosis 20°- 40°
Sacral Kyphosis
Lumbar Lordosis 30°- 50°
Thoracic Kyphosis 20°- 40°
Sagittal Plane Curves

17. Regions of the Spine
 Cervical
 Upper cervical: C1-C2
 Lower cervical: C3-C7
• Sacrococcygeal: 9
fused vertebrae
in the sacrum
and coccyx.
• Thoracic: T1-T12
• Lumbar: L1- L5

18. Regions of the Spine
Line of gravity
Auricle of the ear
Odontoid
Body of C7
Anterior to
thoracic spine
Posterior to
L3
Mid femoral
heads

19. Internal Structure of the Spinal Cord
 A transverse section of the adult spinal cord shows
white matter in the periphery, gray matter inside, and a
tiny central canal filled with CSF at its center.
 Surrounding the canal is a single layer of cells, the
ependymal layer. Surrounding the ependymal layer is
the gray matter – a region containing cell bodies –
shaped like the letter “H” or a “butterfly”.
 The two “wings” of the butterfly are connected across
the midline by the dorsal gray commissure and below
the white commissure.

20. Gray matter
 The shape and size of the
gray matter varies
according to spinal cord
level.
 At the lower levels, the
ratio between gray matter
and white matter is
greater than in higher
levels, mainly because
lower levels contain less
ascending and descending
nerve fibers.

22. Gray matter

23. White Matter
 The white matter, which consists of longitudinal bundles
of nerve fibres, is divided into three columns on each
side.
 Anterior column
 Lateral column
 Posterior column
 Anterior column: contains ascending and crossed fibres
in the ventral spino-thalamic tract, along with the
descending fibres in the olivo-spinal, vestibulo-spinal,
tecto-spinal, and ventral cortico-spinal tracts.

24.  Lateral column: contains the major descending motor
pathway, lateral cortico-spinal tract, with the smaller
descending rubro-spinal tract and the ascending and
crossed spinothalamic tract.
 Dorsal column: contains the uncrossed gracile and
cuneate fascicles.
 In the lateral cortico-spinal tract the descending motor
neurons destined for the lumbo-sacral segments run
laterally to those destined for the cervical segments.
 In posterior columns fibres from the lower limbs lie
more medial than those ascending from the upper
limbs.

25. White matter

26. Arrangement of fibers
Posterior column- As they do not cross at the entry
point in the spinal cord segments, the fibres from
the lower limbs are placed more medially near the
central canal. The fibres from the upper limbs are
placed more laterally.
- Medial to lateral at cervical level: Sacral, lumbar,
thoracic, and cervical respectively.
- Central canal to dorsum: (anterior to posterior)
touch, position, movement, vibration and pressure.

27. Medial to lateral at
cervical level: Sacral,
lumbar, thoracic, and
cervical respectively.
Central canal to dorsum:
(anterior to posterior)
touch, position,
movement, vibration and
pressure

28. Lateral column and anterior column:
- Corticospinal tract
- Spinothalamic tract
 As the fibers cross in the spinal cord, the lower limb fibers
are placed more laterally, and the upper limb fibers are
placed more medially at the cervical level.
 Medial to lateral- Cervical, thoracic, lumbar and sacral(CTLS)

29. Corticospinal tract
Spinothalamic tract
 As the fibers cross in the
spinal cord, the lower limb
fibers are placed more
laterally, and the upper limb
fibers are placed more
medially at the cervical
level.
 Medial to lateral- Cervical,
thoracic, lumbar and
sacral(CTLS)

30. Spinal Cord Nuclei and Laminae
 Spinal neurons are organized into nuclei and laminae.
 Nuclei
 The prominent nuclear groups of cell columns within the
spinal cord from dorsal to ventral are the:
- marginal zone
- substantia gelatinosa
- nucleus proprius
- dorsal nucleus of Clarke
- intermediolateral nucleus
- lower motor neuron nuclei.

31. Rexed Laminae-anatomy and function
The distribution of cells and fibers within the gray
matter of the spinal cord exhibits a pattern of
lamination.
The cellular pattern of each lamina is composed of
various sizes or shapes of neurons
(cytoarchitecture) which led, Rexed to propose a
new classification based on 10 layers (laminae).

32. Rexed Laminae-cont
• Laminae I to IV- are
concerned with
exteroceptive sensation.
• Laminae V and VI are
concerned primarily with
proprioceptive sensations.
• Lamina VII- acts as a relay
between muscle spindle to
midbrain and cerebellum.
• Laminae VIII-IX- The axons of
these neurons innervate
mainly skeletal muscle.
• Lamina X surrounds the
central canal and contains
neuroglia.

33. MENINGES
• Within the spinal canal, the spinal cord is
surrounded by the EPIDURAL SPACE, filled with
fatty tissue, veins, and arteries. The fatty tissue
acts as a shock absorber.
The spinal cord is covered by MENINGES
which has three layers.

34. MENINGES
Dura mater
Subdural
spaceArachnoid
layer
Subarachnoid
space: filled
with CSF
Pia
mater

35. Blood supply of spinal cord
 Anterior spinal artery
 Posterior spinal arteries
 Segmental spinal arteries
- radicular arteries
 Feeder arteries
- Adamkiewicz

36.  There are two posterior spinal arteries, each derived
from the corresponding vertebral or posterior inferior
cerebellar artery.
 These two vessels traverse the length of spinal cord
lying just in front of, or just behind the dorsal nerve
roots.
 There is a single anterior spinal artery formed by the
union of a branch from each vertebral artery which
descends throught the length of the spinal cord in the
anterior median fissure.

37. Blood supply of spinal cord
 The arterial blood supply to the spinal cord in the upper
cervical regions is derived from two branches of the
vertebral arteries, the anterior spinal artery and the
posterior spinal arteries.
 These travel in the subarachnoid space and send
branches into the spinal cord.
 The spinal arteries are reinforced at each intervertebral
foramen by segment arteries derived from the verterbral
costo-cervical trunk, intercostal and lumbar arteries.

39. Blood supply-cont
 At spinal cord regions below upper cervical levels, the
anterior and posterior spinal arteries narrow and form
an anastomotic network with radicular arteries.
 The posterior spinal arteries are paired and form an
anastomotic chain over the posterior aspect of the
spinal cord. A plexus of small arteries, the arterial
vasocorona, on the surface of the cord constitutes an
anastomotic connection between the anterior and
posterior spinal arteries.
 This arrangement provides uninterrupted blood
supplies along the entire length of the spinal cord.

40. Artery of Adamkiewicz
 The artery of Adamkiewicz (also arteria radicularis
magna) is the largest anterior segmental medullary
artery. The artery is named after Albert Adamkiewicz.
 It typically arises from a left posterior intercostal artery
which branches from the aorta at the level of the T9 and
L2, and supplies the lumbar enlargement .
 It is also known as
- Great radicular artery of Adamkiewicz.
- Major anterior segmental medullary artery.
- Artery of the lumbar enlargement.

41. posterior 3rd of spinal cord
dorsal column
penetrating branches
• anterior and part of gray matter
circumferential branches
• anterior white matter

42. Applied anatomy
 Anterior spinal artery syndrome-
the primary blood supply to the
anterior portion of the spinal
cord, is interrupted,
causing ischemia or infarction of
the spinal cord in the anterior
two-thirds of the spinal cord
and medulla oblongata.
 It is characterized by loss
of motor function below the level
of injury, loss of sensations carried
by the anterior columns of the
spinal cord (pain and
temperature)

43.  Posterior cord syndrome is a condition caused by lesion
of the posterior portion of the spinal cord. It can be
caused by an interruption to the posterior spinal artery.
 Unlike anterior cord syndrome, it is a very rare
condition.
 Clinical presentation:
 Loss of proprioception + vibration sensation + loss of
two point discrimination +loss of light touch

44. Venous Drainage
 The spinal veins derived from the spinal cord substance
terminate in a plexus in the pia mater where there are
six tortous, often plexiform longitudinal channels,
-one along the anterior median fissure
- a second along the posterior median sulcus
- two situated on either side,
- one pair just behind and the other just in front of the
ventral and dorsal nerve roots.
 These six vessels communicate freely with one other
and above pass into the corresponding veins of the
medulla oblongata and drain into the intracranial
venous sinuses.

45. Venous drainage-cont
 The posterior half of the cord is drained by posterior
medullary veins, the anterior medullary group has one
lateral and two medial groups.

46. Veins of the Thoracic and Lumbar Region
Internal
jugular
Superior
vena cava
Azygos
vein
Thoracic
segmental
veins
Hemiazygos
vein
Lumbar
segmental
veins
Inferior
vena cava
Common
iliac
veins

47. Batson’s Plexus
• The AZYGOS SYSTEM is a large network of
veins draining blood from the intestines and
other abdominal organs back to the heart.
• The segmental veins drain into the azygos vein
located on the right side of the abdomen, or
into the hemiazygos vein located on the left
side.

48.  The azygos system also communicates with a valveless
venous network known as BATSON’S PLEXUS.
 When the vena cava is partially or totally occluded, Batson’s
plexus provides an alternate route for blood return to the
heart.
 The vessels of Batson’s plexus may be referred to as epidural
veins Batson’s
plexus

49. Batson’s Plexus-applied anatomy
• Because of the azygos system, patient positioning is
very important in posterior lumbar spine surgery.
• The patient’s abdomen should always hang free and
without abdominal pressure.
• An increase in pressure will diminish flow through the
azygos system and the vena cava. This results in an
increase of venous flow into Batson’s plexus with a
corresponding increase of blood loss.

50. Communications and Implications
 Valveless vertebral system of veins communicates:
- Above with the intracranial venous sinuses.
- Below with the pelvic veins, the portal vein, and the
caval system of veins.
 The veins are valveless and the blood can flow in them
in either direction. Such flow are clinically important
because they make possible spread of tumors or
infections.

51. Ascending And Descending
tracts

52. The ascending tracts

54. Ascending tracts
 Bundles of nerve fibers linking spinal cord with higher
centers of the brain, convey information from somatic
or viscera to higher level of neuraxis.
 Ascending sensory pathway are organized in
three neuronal chain :
- First order neuron
- Second order neuron
- Third order neuron.

55. First order neuron
 Cell body in posterior root ganglion
 Peripheral process connects with sensory receptor
ending.
 Central process enter the spinal cord through the
posterior root.
 Synapse with second order neuron in spinal gray
matter.

56. dorsal root
dorsal root
ganglion
spinal
nervedorsal
horn
FIRST ORDER NEURON

57. Second order neuron
Cell body in posterior gray column of spinal cord
Axon crosses the midline ( decussate )
Ascend and synapse with third order neuron in
Venteropostero lateral(VPL) nucleus of thalamus.

58. SECOND ORDER NEURON
• cross the mid line
• in front of central canal
VPL
1st
2nd

59. Third order neuron
cell body in the thalamus
Give rise to projection fibres to the cerebral cortex,
postcentral gyrus ( sensory area )

60. ascending sensory pathway
( in general form )
from sensory endings
to
cerebral cortex
( note the three neurons chain )

61. ascending tracts in spinal cord

62. sensation receptors pathways destination
Pain and temperature Free nerve endings Lateral STT
Spinal lemniscus
Postcentral
gyrus
Light touch and pressure Free nerve endings Anterior STT
Spinal lemniscus
Postcentral
gyrus
Discriminative touch,
vibratory sense,
conscious muscle joint
sense
Meissner’s
corpuscle, pacinian
corpuscles,
muscle spindles,
tendon organs
Fasciculus gracilis and
cuneatus
Medial lemniscus
Postcentral
gyrus
Main somatosensory pathways

63.  Pain and thermal impulses
( input from free nerve endings, thermal receptors )
 Transmitted to spinal cord in delta A and C fibers
 Central process enters the spinal cord through
posterior nerve root, proceed to the tip of the dorsal
gray column.
Lateral spinothalamic tract

64. The central process of 1st order neuron synapse with
cell body of 2nd order neuron in substantia gelatinosa
of posterior gray column of the spinal cord.
The axon of 2nd order neuron cross to the opposite
side in the anterior gray and white commissure and
ascend in contralateral white column as lateral
spinothalamic tract.
End by synapsing with 3rd order neuron in the ventral
posterolateral nucleus of thalamus.
Lateral spinothalamic tract-cont

65. Axon of the 3rd order neuron passes through the
posterior limb of internal capsule and corona
radiata to reach the postcentral gyrus of cerebral
cortex ( area 3, 1 and 2 )

66. pain and temperature pathways

67. Clinical application
destruction of LSTT
loss of
 pain and thermal sensation
 on the contralateral side
 below the level of the lesion
patient will not
respond to pinprick
recognize hot and cold

68.  Light touch and pressure impulses
( input from free nerve endings, Merkel’s tactile disks )
 First order neuron
 Dorsal root ganglion( all level )
 Second order neuron
 In the dorsal horn, cross to the opposite side (decussate)
 Ascend in the contralateral ventral column as ASTT
 End in VPL nucleus of thalamus
 Third order neuron
 In the VPL nucleus of thalamus
 Project to cerebral cortex ( area 3, 1 and 2 )
Anterior spinothalamic tract

69. touch and pressure pathways

70. Clinical application
destruction of ASTT
loss of touch and pressure sense
below the level of lesion
on the contralateral side of the body

71. Fasciculus gracilis and fasciculus cuneatus
Discriminative touch, vibratory sense and conscious
muscle joint sense.
( inputs from pacinian corpuscles, Messiner’s corpuscles, joint
receptors, muscle spindles and Golgi tendon organs )
Axon of 1st order neuron enter the spinal cord
Passes directly to the posterior white column of the
same side ( without synapsing )

72. Long ascending fibres travel upward in the posterior
column of the same side as fasciculus gracilis and
fasciculus cuneatus.
 ( FG – carrying fibres from lower thoracic, lumbar and sacral regions / including
lower limbs )
 ( FC - only in thoracic and cervical segments / including upper limb fibres )
synapse on the 2nd order neuron in the nucleus gracilis
and cuneatus of medulla oblongata of the same side.

73. lower 6 thoracic segments
lumbar segments
sacral segments
cervical segments
upper 6 thoracic segments
fasciculus gracilis
fasciculus cuneatus
[ nucleus G & C ]
in medulla
G
C

74.  Axons of 2nd order neuron “
internal arcuate fibres ” cross the
median plane( sensory
decussation)
 Ascend as medial lemniscus
through medulla oblongata, pons,
and midbrain
 Synapse on the 3rd order neuron in
ventral posteriolateral nucleus of
thalamus
 Axon of 3rd order neuron leaves and
passes through the internal capsule,
corona radiata to reach the
postcentral gyrus of cerebral cortex
area 3, 1 and 2 )

75. pathways for
conscious proprioception
discriminative touch
vibratory sense

76. Clinical application
destruction of
fasciculus gracilia and cuneatus
 loss of muscle joint sense, position
sense, vibration sense and tactile
discrimination
 on the same side
 below the level of the lesion

77. Posterior and anterior spinocerebellar
tract
Transmit unconscious proprioceptive information
to the cerebellum.( length and tension of muscle
fibers)
Receive input from muscle spindles, Golgi Tendon
Organs and pressure receptors.
Involved in coordination of posture and movement
of individual muscles of the lower limb.

78. First order neuron
 In dorsal root ganglion
 Axons end in nucleus dorsalis of Clarke
Second order neuron
 Cell body in nucleus dorsalis of Clarke
 Give rise to axons ascending to the cerebellum of the same
side.
( anterior – crossed & uncrossed fibres / posterior –
uncrossed fibres)

79. Muscle, joint sense pathways to cerebellum

80. Spinoreticular tract
 The spinoreticular tract is an ascending pathway in the
white matter of the spinal cord, positioned closely to
the lateral spinothalamic tract. The tract is from spinal
cord—to reticular formation to thalamus.
 It is responsible for automatic responses to pain, such
as in the case of injury .

82. Descending tracts
• The pyramidal tracts include both
the corticospinal and corticobulbar tracts.
• These are aggregations of upper motor neuron nerve
fibres that travel from the cerebral cortex and
terminate either in the brainstem(corticobulbar)
-or spinal cord(corticospinal) and are involved in
control of motor functions of the body.

84. Corticospinal Tracts
 The corticospinal tracts begin in the cerebral cortex,
from which they receive a range of inputs:
 Primary motor cortex
 Premotor cortex
 Supplementary motor area
 They also receive nerve fibres from the somatosensory
area, which play a role in regulating the activity of
the ascending tracts.

85.  After originating from the cortex, the
neurons converge, and descend
through the internal capsule.
 After the internal capsule, the neurons
pass through the crus cerebri of the
midbrain, the pons and into
the medulla.
 In the most inferior (caudal) part of the
medulla, the tract divides into two:
1) lateral corticospinal tract:
which supply the muscles of the
body.
2) anterior corticospinal
tract: ipsilateral, descending into the
spinal cord. They then decussate and
terminate in the ventral horn of
the cervical and upper thoracic
segmental levels.

86.  At the caudal part of medulla
oblongata
 Most of the fibres 90 % cross the
mid line (motor decussation)
 descend in the lateral column as
LCST
 terminate on LMN of anterior
gray column at all spinal level
 Remaining uncrossed fibres
descend as ACST
 eventually fibres cross the mid
line and terminate on LMN of
anterior gray column of
respective spinal cord segments.

87. Corticobulbar Tracts
 The corticobulbar tracts arise from the lateral aspect of
the primary motor cortex. They receive the same inputs
as the corticospinal tracts. The fibers converge and pass
through the internal capsule to the brainstem.
 The neurons terminate on the motor nuclei of
the cranial nerves. Here, they synapse with lower
motor neurons, which carry the motor signals to the
muscles of the face and neck.

88.  Fibres from the ventral motor
cortex travel with the corticospinal
tract through the internal capsule,
but terminate in a number of
locations in the midbrain (cortico-
mesencephalic
tract), pons (Corticopontine tract),
and medulla oblongata (cortico-
bulbar tract).
 The nerves within
the corticobulbar tract are involved
in movement in muscles of the head.
They are involved in
swallowing, phonation, and
movements of the tongue.

89. Clinical significance
 Fibers of the corticospinal tracts are damaged anywhere
along their course from the cerebral cortex to the lower
end of the spinal cord, this will give rise to an upper
motor neuron syndrome.
 If the corticobulbar tract is damaged on only one side,
then only the lower face will be affected, however if
there is involvement of both the left and right tracts,
then the result is pseudobulbar palsy.

90. Extrapyramidal Tracts
 The extrapyramidal tracts originate in the brainstem,
carrying motor fibres to the spinal cord.
 They are responsible for
the involuntary and automatic control of all
musculature, such as muscle tone, balance, posture and
locomotion.
 There are four tracts in total.
The vestibulospinal and reticulospinal tracts do not
decussate, providing ipsilateral innervation.
The rupbrospinal and tectospinal tracts do decussate,
and therefore provide contralateral innervation.

91. Vestibulospinal tract
 There are two vestibulospinal
pathways; medial and lateral.
 They arise from the vestibular
nuclei, which receive input from
the organs of balance.
 The tracts convey this balance
information to the spinal cord,
where it remains ipsilateral.
 Fibres in this pathway
control balance and posture by
innervating the ‘anti-gravity’
muscles (flexors of the arm, and
extensors of the leg), via lower
motor neurones.

92. Reticulospinal Tracts
 The two recticulospinal tracts have differing functions:
 The medial reticulospinal tract arises from the pons. It
facilitates voluntary movements, and increases muscle
tone.
 The lateral reticulospinal tract arises from the medulla. It
inhibits voluntary movements, and reduces muscle tone.
Nerve cells in reticular formation
Fibres pass through
 midbrain, pons, and medulla oblongata
End at the anterior gray column of spinal cord
 control activity of motor neurons

93. Reticulospinal tract

94. Rubrospinal Tracts
 In the midbrain, it originates in the red nucleus, crosses
to the other side of the midbrain, and descends in the
lateral part of the brainstem tegmentum.
 The tract is responsible for large muscle movement as
well as fine motor control, and it terminates primarily in
the cervical spinal cord, suggesting that it functions in
upper limb but not in lower limb control.

95. Rubrospinal tract
 Nerve cells in red nucleus
( tegmentum of midbrain at the
level of superior colliculus )
 Nerve fibres / axons
 cross the mid line
 descend as rubrospinal
tract
 through pons and
medulla oblongata
Terminate in anterior gray
column of spinal cord
( facilitate the activity of flexor
muscles )

96. Tectospinal Tracts
 This pathway begins at
the superior
colliculus of the
midbrain. The
superior colliculus is a
structure that receives
input from the optic
nerves.
 The neurones then
quickly decussate, and
enter the spinal cord.
They terminate at the
cervical levels of the
spinal cord.

97. Tectospinal tract-cont
 This neural tract is part of the indirect extrapyramidal
tract. To be specific, the tectospinal tract connects
the midbrain tectum and the spinal cord.
 It is responsible for motor impulses that arise from one
side of the midbrain to muscles on the opposite side of
the body. The function of the tectospinal tract is to
mediate reflex postural movements of the head in
response to visual and auditory stimuli.
 The tract descends to the cervical spinal cord to
terminate in Rexed laminae VI, VII, and VIII to
coordinate head, neck, and eye movements, primarily in
response to visual stimuli.

98. lower motor neurons ( LMN )
Motor neurons that innervate the voluntary muscles
 In anterior gray column of spinal cord.
 Motor nuclei of brainstem
 innervate skeletal muscles
form final common pathway
LMN

99.  Lower motor neuron are constantly bombarded by nerve
impulses( excitatory or inhibitory) that descend from
cerebral cortex, pons, midbrain and medulla.
 sensory inputs are from the posterior root.

100. Cord syndromes
 Complete transverse cord lesion
 Central cord syndrome
 Anterior cord syndrome
 Posterior cord syndrome
 Brown- sequard syndrome.

101. Lesions of central gray matter central cord syndrome
 Seen in syringomyelia ( progressive cavitation around or
near the central canal of spinal cord especially in cervical
segments)
 Interrupt fibres of lateral spinothalamic tract that passes
in front of the central canal.
 Loss of pain and temperature sensibility on both sides
proprioception and light touch is spared.
sensory dissociation.

103. Anterior cord syndrome
 Anterior spinal artery syndrome-
the primary blood supply to the
anterior portion of the spinal
cord, is interrupted,
causing ischemia or infarction of
the spinal cord in the anterior
two-thirds of the spinal cord
and medulla oblongata.
 It is characterized by loss
of motor function below the level
of injury, loss of sensations carried
by the anterior columns of the
spinal cord (pain and
temperature)

104. Posterior cord syndrome
 Is a condition caused by lesion of the posterior portion
of the spinal cord. It can be caused by an interruption to
the posterior spinal artery.
 Unlike anterior cord syndrome, it is a very rare
condition.
 Clinical presentation:
 Loss of proprioception + vibration sensation + loss of
two point discrimination +loss of light touch

105. Brown-Sequard syndrome
Hemisection of the spinal cord
 Dorsal column damage
 Lateral column damage
 Anterolateral column damage
 Damage to local cord segment and nerve roots

106. spinal cord hemisection

107. below the level of lesion
on the side of lesion
lateral column damage
• UMNL
dorsal column damage
• loss of position sense
• loss of vibratory sense
• loss of tactile discrimination
anterolateral system damage
• loss of sensation of pain and
temperature on the side opposite
the lesion
local segment
side of lesion
Dorsal Root
• irritate
• destruction
Ventral root
• flaccid paralysis

108. Conus syndrome
 Caused by S3 and S5 lesions.
 Saddle anaesthesia(s3-s5)
 Urinary retention with overflow incontinence( due to
detrusor areflexia)
 Fecal incontinence.
 Impotence.
 Loss of anal reflexes(S4-S5) and bulbocavernosus(S2-
S4).
 Preserved motor function of lower limbs.

109. Cauda equina syndrome
 Cauda equine is composed of lumbar, sacral, and
coccygeal nerve roots.
 Lesions of the cauda equine below L1 vertebral level
result in cauda equina syndrome.
 Lesions affecting the upper portion of the cauda equine
result in the:
- Sensory deficits in the legs and saddle area, usually
asymmetrical flaccid paralysis of lower limbs with
arflexia.
- Urinary retention with overflow incontinence, fecal
incontinence with impotence and loss of anal tone.

110. Cauda equina syndrome
 Lesions affecting the lower portion of cauda equine may
have lower limb weakness but sensory loss only in
saddle area along with involvement of urination,
defecation and sexual dysfunction.

111. Thank you

112. References
 Dejong’s The neurologic examination. sixth edition.
 Harrisons principles of internal medicine.19th edition.
 Brain’s textbook of neurological disorders.
 B.D.Chourasia textbook of anatomy.
 Bickerstaff neurological examination.
 Grays textbook of anatomy.