Anatomy and blood supply of spinal cord

spinal cord

1. Anatomy and blood supply of spinal cord Dr. Nishtha Jain Senior Resident Department of Neurology GMC, Kota

2. Part of the central nervous system (CNS) Extends caudally Protected by the bony structures of the vertebral column. Covered by the three membranes of the CNS, i.e., the dura mater, arachnoid and the innermost pia mater. Occupies only the upper 2/3 of the vertebral canal.

3. By age 2 months, it reaches the adult L1-L2 level. The average length- 45 cm(adult male) and 42 to 43 cm(adult female). The corresponding average length of the spinal column is 70 cm. If the level of the tip of the conus is below the mid-L2 vertebral body, the conus is considered low-lying.

4. According to its rostrocaudal location the spinal cord can be divided into four parts: -cervical, -thoracic, -lumbar and -sacral.

5. The number of spinal nerves and spinal segments: -8 cervical, -12 thoracic, -5 lumbar, -5 sacral and -one coccygeal spinal segment

6. SPINAL CORD LEVELS RELATIVE TO THE VERTEBRAL BODIES SPINAL CORD LEVEL CORRESPONDING VERTEBRAL BODY Upper cervical Same as cord level Lower cervical +1 Upper thoracic +2 Lower thoracic + 2 to 3 levels Lumbar T 10 – T 12 Sacral T 12 – L1

7. ENLARGEMENTS ENLARGEMENTS : contains more motor neurons to supply the limbs • Cervical: Extends from C5 to T1 segments to form brachial plexus widest circumferance-38mm at C6 Lumbosacral : Extends from L2toS3 to form lumbosacral plexus. Widest circumferance -35mm at S1

8. LAMINA I Nucleus posteromarginalis II Substantia gelatinosa III and IV Nucleus proprius dorsalis V Zone anterior to lamina IV VI Zone at the base of dorsal horn VII Intermediate zone VIII Zone in the ventral horn (restricted to medial aspect in cervical and lumbar enlargements) IX Medial and lateral anterior horn cell columns. X cells surrounding the central canal

9. PATHWAYS IN THE SPINAL CORD Ascending (afferent) pathways Descending (efferent) pathways

10. Descending tracts Five descending systems exert tonic effects on the motor neurons. The vestibulospinal tract and The medial reticulospinal tract tend to facilitate the motor neurons of antigravity muscles. The corticospinal tract, The corticorubrospinal tract, and The lateral reticulospinal tract inhibit the antigravity muscles and facilitate the antagonists.

11. VESTIBULOSPINAL TRACT RETICULOSPINAL TRACT

12. RUBROSPINAL TRACT TECTOSPINAL TRACT

13. LATERAL SPINOTHALAMIC TRACT

14. ANTERIOR SPINOTHALAMIC TRACT

15. SPINOCEREBELLAR TRACT

16. HEMISECTION OF SPINAL CORD (BROWN-SEQUARD SYNDROME)

17. Central cord syndrome Seen in syringomyelia Interrupt fibres of lateral spinothalamic tract that passes in front of the central canal. sensory dissociation

18. Arterial Supply to the Spinal Cord

19. Anterior spinal artery : ORIGIN: Branches of right and left vertebral arteries in the upper cervical canal. COURSE: runs caudally in the anterior median fissure. TERMINATION: filum terminale SUPPLIES: Anterior two third of the cord

20. Two posterior spinal arteries : ORIGIN : Branched from either 1. Vertebral 2.Posterior inferior cerebellar arteries. COURSE: Runs down in the posterolateral sulcus divides into two collateral arteries medial and lateral along the posterior nerve roots. These communicate around the cord forming pial plexus arterial vaso corona/ arteriae coronae. SUPPLIES :Posterior one third of the cord

21. Segmental arteries : Branches of Deep cervical, Ascending cervical, Intercostal and Lumbar Segmental arterial feeders reach the cord as anterior and posterior radicular arteries. ANTERIOR RADICULAR ARTERIES: Larger and less in number. POSTERIOR RADICULAR ARTERIES: Smaller and more in number. Great anterior medullary artery of Adamkiewicz -arises from aorta at T12 or L1 vertebral level unilateral left side

22. Anterior Spinal Artery Syndrome -Back or neck pain of sudden onset -Rapidly progressive flaccid and areflexic paraplegia -Loss of pain and temperature to a sensory level -Preservation of proprioception and vibration sensation -Urinary incontinence

23. Posterior spinal artery syndrome -Loss of proprioception and vibratory sense -Preserved pain and temperature sensation -Loss of myotatic and cutaneous reflexes below involved segment -Absence of motor deficits

24. VENOUS DRAINAGE Two median longitudinal Two anterolaterlal Two posterolateral

25. Drain below through internal vertebral venous plexus into the vertebral posterior intercostal , lumbar, and lateral sacral veins. And drain above into the basilar venous plexus.

26. THANK YOU

27. Referrences Localization in clinical neurology by Paul W. Brazis 6 th edition Bradley’s Neurolgy in clinical practice 6 th edition DeJong's The Neurologic Examination, 6th Edition Textbook of Human Neuroanatomy by Inderbir Singh 9 th edition Anatomy and Physiology of the Spinal Cord. Madame Curie Bioscience Database