Spinal cord

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

1. Anatomy, Blood supply and sections of Spinal C ord 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. Functions of the Spine Structural support and balance for upright posture The spine is the axle bearing the load of the head, shoulders and thorax. The upper body weight is then distributed to the lower extremities through the sacrum and pelvis. This reduces the amount of work required by the spinal muscles and can eliminate muscle fatigue and back pain.

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

18. 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

19. 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

20. 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.

21. 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. L aminae V and VI are concerned primarily with proprioceptive sensations . Lamina VII- acts as a relay between muscle spindle to midbrain and cerebellum. L aminae 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 space Arachnoid 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 . T he spinal arteries are reinforced at each intervertebral foramen by segment arteries derived from the verterbral costo -cervical trunk, intercostal and lumbar arteries.

38. 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.

39. Artery of Adamkiewicz T he   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.

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

41. 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)

42. 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

43. 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 w ith one other and above pass into the corresponding veins of the medulla oblongata and drain into the intracranial venous sinuses.

44. 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.

45. 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

46. 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.

47. 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

48. 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.

49. 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.

50. Ascending And Descending tracts

51. The ascending tracts

52. 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.

53. First order neuron C ell body in posterior root ganglion P eripheral process connects with sensory receptor ending. C entral process enter the spinal cord through the posterior root. S ynapse with second order neuron in spinal gray matter.

54. dorsal root dorsal root ganglion spinal nerve dorsal horn FIRST ORDER NEURON

55. Second order neuron C ell body in posterior gray column of spinal cord A xon crosses the midline ( decussate ) A scend and synapse with third order neuron in Venteropostero lateral(VPL) nucleus of thalamus.

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

57. Third order neuron cell body in the thalamus G ive rise to projection fibres to the cerebral cortex, postcentral gyrus ( sensory area )

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

59. ascending tracts in spinal cord

60. 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

61. P ain and thermal impulses ( input from free nerve endings, thermal receptors ) T ransmitted to spinal cord in delta A and C fibers C entral process enters the spinal cord through posterior nerve root, proceed to the tip of the dorsal gray column. Lateral spinothalamic tract

62. T he central process of 1 st order neuron synapse with cell body of 2 nd order neuron in substantia gelatinosa of posterior gray column of the spinal cord. The axon of 2 nd 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 3 rd order neuron in the ventral posterolateral nucleus of thalamus. Lateral spinothalamic tract- cont

63. A xon of the 3 rd 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 )

64. pain and temperature pathways

65. 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

66. L ight touch and pressure impulses ( input from free nerve endings, Merkel’s tactile disks ) First order neuron D orsal root ganglion( all level ) Second order neuron I n the dorsal horn, cross to the opposite side (decussate) A scend in the contralateral ventral column as ASTT E nd in VPL nucleus of thalamus Third order neuron I n the VPL nucleus of thalamus P roject to cerebral cortex ( area 3, 1 and 2 ) Anterior spinothalamic tract

67. touch and pressure pathways

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

69. 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 ) A xon of 1 st order neuron enter the spinal cord P asses directly to the posterior white column of the same side ( without synapsing )

70. L ong 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 2 nd order neuron in the nucleus gracilis and cuneatus of medulla oblongata of the same side.

71. 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

72. A xons of 2 nd order neuron “ internal arcuate fibres ” cross the median plane ( sensory decussation) A scend as medial lemniscus through medulla oblongata, pons, and midbrain S ynapse on the 3 rd order neuron in ventral posteriolateral nucleus of thalamus A xon of 3 rd order neuron leaves and passes through the internal capsule, corona radiata to reach the postcentral gyrus of cerebral cortex area 3, 1 and 2 )

73. pathways for conscious proprioception discriminative touch vibratory sense

74. 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

75. Posterior and anterior spinocerebellar tract T ransmit unconscious proprioceptive information to the cerebellum.(   length and tension of muscle fibers ) R eceive input from muscle spindles, Golgi Tendon Organs and pressure receptors. I nvolved in coordination of posture and movement of individual muscles of the lower limb.

76. First order neuron I n dorsal root ganglion A xons end in nucleus dorsalis of Clarke Second order neuron C ell 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 )

77. Muscle, joint sense pathways to cerebellum

78. 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 .

79. 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 .

80. 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.

81. 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 : lateral corticospinal tract: which  supply the muscles of the body . 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.

82. A t the caudal part of medulla oblongata M ost 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 R emaining uncrossed fibres descend as ACST eventually fibres cross the mid line and terminate on LMN of anterior gray column of respective spinal cord segments.

83. 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 .

84. 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.

85. 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.

86. 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.

87. 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 .

88. 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

89. R eticulospinal tract

90. 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.

91. 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 )

92. 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.

93. 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.

94. lower motor neurons ( LMN ) M otor neurons that innervate the voluntary muscles I n anterior gray column of spinal cord. M otor nuclei of brainstem innervate skeletal muscles form final common pathway LMN

95. 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.

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

97. Lesions of central gray matter central cord syndrome S een in syringomyelia ( progressive cavitation around or near the central canal of spinal cord especially in cervical segments) I nterrupt fibres of lateral spinothalamic tract that passes in front of the central canal. L oss of pain and temperature sensibility on both sides proprioception and light touch is spared. sensory dissociation.

98. 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)

99. Posterior cord syndrome   I s 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

100. 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

101. spinal cord hemisection

102. 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

103. 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.

104. 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.

105. 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.

106. Thank you

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