Spinal cord=dr.khalid latifawan

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Spinal cord=dr.khalid latifawan

  1. 1. SPINAL CORD
  2. 2. SPINAL CORD  Brain and spinal cord are parts of the central Nervous system , except them everything else comes under P.N.S. It performs two main functions  1 -conduction of impulses to and from the brain  2 -it processes sensory information in a limited manner, making it possible for the cord to initiate stereotyped reflex actions ( spinal reflexes with out input from higher centers in the brain).
  3. 3. SPINAL CORD Spinal cord weighs about 30 grams , comprises 2% of the adult brain weight 1 cm In diameter Average length 45 cm in male 42 cm in female
  4. 4. SPINAL CORD  A. LOCATION  B.ATTACHMENTS  –denticulate ligaments Suspend and Anchor the spinal cord within the DURAL SAC and arises from the vascular pia matter - filum terminale -spinal nerve roots
  5. 5. GENERAL STRUCTURE OF SPINAL CORD
  6. 6. GENERAL STRUCTURE OF SPINAL CORD
  7. 7. GENERAL STRUCTURE OF SPINAL CORD Conus medullaris = Tip of spinal cord filum terminale = a pial filament Extending from C. medullaris to the end of dural sac. With which it fuses. Which extend up to the level of L1 and L2 31 pairs of mixed (motor and sensory ) spinal nerves which passes through intervertebral forminae except C1
  8. 8. GENERAL STRUCTURE OF SPINAL CORD Cervical nerves C1-C8 Thoracic nerves T1-T12 Lumbar nerves L1-L5 Sacral nerves S1-S5 Cocygeal nerve
  9. 9. GENERAL STRUCTURE OF SPINAL CORD Each portion of the cord that gives rise to a pair of spinal nerves is called a spinal segment At the end of spinal cord,the descending lumber and sacral roots has the appearance of a horse tail and therefore ---- cauda equina Cervical enlargement ----- upper limb (C5-T1)  Brachial plexus Lumber enlargment ------ lower limb (L1-S2)  Lumbo sacral plexus
  10. 10. SPECIAL CONSIDERATION -The C1 and the cocceygeal nerves usually have no dorsal (sensory) roots and no corresponding dermatome -C1 passes between the atlas and skull -C2 between atlas and axis vertebrae -All cervical spinal nerves passes above the vertebrae
  11. 11. FUNCTIONAL COMPONENTS OF SPINAL NERVE
  12. 12. COMPONENTS AND BRANCHES OF SPINAL NERVE
  13. 13. COMPONENTS AND BRANCHES OF SPINAL NERVE
  14. 14. COMPONENTS AND BRANCHES OF SPINAL NERVE D. White communicating ramus contains myelinated Preganglionic sympathetic fibers and myelinated GVA -are found only in THORACOLUMBER segments of the spinal cord T1-L3
  15. 15. MENINGES  GREEK=membrane SINGULAR meninex  PIA MATTER , LATIN=faithful, gentle, pious  ARACHNOID MATTER, GREEK=spider or web  DURA MATTER, LATIN=tough
  16. 16. MENINGES OF THE SPINAL CORD
  17. 17. MENINGES OF THE SPINAL CORD ARACHNOID: mater forms a close lining of the dura mater . The sub arachnoid space contains C.S.F. It is largest in the region of the cauda equina. PIA MATER contains a rich network of blood vessels. Spinal cord is held in a some what fixed position with in the meninges by fibrous bridges that cross the subarachnoid spaces joining pia mater arachnoid and dura mater. The heaviest of the bridges are the denticulate ligaments.
  18. 18. COMPOSITION OF SPINAL CORD  Like brain spinal cord consists of areas of  white – myelinated processes of neurons  and gray – nerves cell bodies and unmyelinated inter neuronal nerve fiber. Neuroglia the supportive cells are present in both white and gray mater. In contrast to cerebrum and cerebellum the gray mater is centrally located and is surrounded by white mater. Gray mater Letter H or butterfly shape
  19. 19. COMPOSITION OF SPINAL CORD Gray commisure Central canal is in the gray commisure Posterior (dorsal) horns Anterior (ventral ) horns In thoracic and lumber regions (T1_L3) Gray mater also include lateral horns.
  20. 20. COMPOSITION OF SPINAL CORD  Alar plate consist of  post horns composed of axons of sensory neurons of spinal nerve and inter neurons that transmit sensory information.
  21. 21. COMPOSITION OF SPINAL CORD
  22. 22. COMPOSITION OF SPINAL CORD  BASAL PLATE consist of  ANTERIOR HORN-somatic motor neurons. Axon leaves the spinal cord and enter a spinal nerve.  LATERAL HORN – visceral motor neurons
  23. 23. COMPOSITION OF SPINAL CORD
  24. 24. FUNCTIONAL COMPONENTS OF A SPINAL NERVE WHITE MATTER OF THE SPINAL CORD: myelinated axons and travel in three direction 1- UP the spinal cord to higher level in the cord or brain. 2-DOWN the spinal cord from the brain or higher levels of the cord. 3-ACROSS the cord , transmitting impulses from one side to the other. white matter of each half of spinal cord is divided by the gray matter into three areas
  25. 25. Post funiculus Lateral funiculus Ant funiculus With in the funiculi there are small bundles of nerve fibers called fasiculi = tracts. A tract carry similar types of impulses to a specific destination and are composed of the conductive processes of neurons.
  26. 26. Ascending sensory = to brain Descending motor = from brain down to the motor neurons in the anterior or lateral gray horns of spinal cord. Most of the tracts have descriptive names that indicate where they begin and where they terminate. Ascending spinal tract (sensory tracts) These tracts of spinal cord carry afferent (sensory)
  27. 27. Impulses from peripheral sensory receptors to various centers in the brain. These tracts generally contain three successive neurons called 1st order (dorsal root ganglia) 2nd order (spinal cord or medulla) 3rd order (thalamus) ↓ ↓ cerebral cortex
  28. 28. Major sensory (Ascending)tracts are 1- fasciculus gracilis 2- fascilculus cuneatus 3- spinothalaamic tract 4- spino cereberullar tract 5 -spino reticular 6-spino mesencephalic
  29. 29. Fasciculus gracilis } proprioception fine touch Fascilis cuneatus lateral spinothalamic } pain and temperature Ant spinothalamic } touch and pressure
  30. 30. Four spino cerebellar tract Anterior spino cerebellar tract Posterior spino cerebellar tract ( unconscious proprioception )
  31. 31. Descending (motor ) spinal tracts Brain  lower motor neurons That regulate the activity of skeletal muscles i.e voluntary skilled motor activity (limbs) All of these tracts cross form one side of CNS to the other and they all contain two or three consecutive neurons .
  32. 32. Two types of descending spinal tracts 1-pyramidal tracts 2-extra pyramidal tracts
  33. 33.  THANK YOU
  34. 34. 1-PYRAMIDAL TRACTS Pyramidal tracts = corticospinal tract = uper motor neurons crossing at medulla to form lateral corticospinal tract 80 % remaining 20 % form anterior conticospinal tract which are uncrossed .
  35. 35. The remaining motor tracts are called extra pyramidal tracts They begin from various nuclei in the brain stem and influence Muscular action Co-ordination Balance Visual and auditory stimuli and other functions
  36. 36. - Rubro spinal tract (crossed) - Vestibulo spinal tract ( uncrossed) - Tecto spinal tract (crossed) - Olivo spinal tract
  37. 37. Over lapping of corticospinal ad extra pyramidal tracts clean separation is not possible. Pyramidal spinal tract = movement of the body Extra pyramidal spinal tract = posture and balance and to modify muscular contraction.

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