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EXTERNAL FEATURES OF SC

EXTERNAL FEATURES OF SC. DR JAMILA ELMEDANY. POSITION & SHAPE. Beginning: At the foramen magnum as a continuation of the Medulla Oblongata of the brain. Shape: Cylindrical. Length: About (45) cm. Occupies: Upper 2/3 of the vertebral (spinal) canal of the vertebral column.

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EXTERNAL FEATURES OF SC

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  1. EXTERNAL FEATURES OF SC DR JAMILA ELMEDANY

  2. POSITION & SHAPE • Beginning: • At the foramen magnum as a continuation of • the • Medulla Oblongata of the brain. • Shape: • Cylindrical. • Length: • About (45) cm. • Occupies: • Upper 2/3 of the vertebral (spinal) canal of the vertebral column.

  3. LEVELS OF TERMINATION IN DIFFERENT AGES • (1) Up till the 3rd month of Fetal Life: • The spinal cord occupies the Entire Length of the vertebral canal. • (2) At birth : • It terminates at the level of L3.

  4. LEVELS OF TERMINATION IN DIFFERENT AGES • (3) Children : • It ends at the Upper Border of the 3rd Lumbar vertebra. • (4) Adults : • It terminates at the Intervertebral disc (1st-2nd )Lumbar vertebrae.

  5. ENLARGEMENTS Cervical: (C3- T1) Segments. • For theBrachial Plexus. Lumbar: (L1- S3) Segments. • For the • Lumbar and Sacral Plexuses.

  6. MODE OF TERMINATION • Conus Medullaris: • A conical termination Caudal to the Lumbar Enlargement. • FilumTerminale: • A filament of connective tissue arises from the tip of the conus. • It is attached to the 1st CoccygealVertebra.

  7. EXTERNAL FEATURES • Anterior: • Deep Anterior(Ventral) • MedianFissure.Posterior: • Shallow Posterior • Median Sulcus.

  8. SPINAL NERVES • The Spinal Cord receives • Information from and Controls the Movement of the Trunk and Limbs. • It has (31) paired Spinal Nerves.

  9. FORMATION OF THE SPINAL NERVE • Two linear series (6-8)of Nerve Fasciclesareattached to theDorsolateral andVentrolateral aspects of the cord. • The Fascicles coalesce toformDorsal andVentralNerve Roots.

  10. FORMATION OF THE SPINAL NERVE • The Roots pass to their correspondingInter vertebral Foramena. • Near which they join to form theSpinal Nerve Proper.

  11. DORSAL ROOTS • Carry: • Primary AfferentNeuronsfrom the peripheral sensory receptors to the spinal cord and brain stem. • Their cell bodies arein theDorsal Root Ganglia.

  12. VENTRAL ROOTS • Carry : • 1.Efferent neurons(Lower Motor Neurons) • Their cell bodies are located in the Spinal Gray matter. • 2.Preganglionic Autonomic neurons.

  13. RAMI • Spinal Nerves areMixed. • Contain: • Both Afferent and Efferent fibers. • Each spinal nerve is divided into • Dorsal andVentral Rami.

  14. RAMI • Dorsal Ramus : • Thin. • Supplies muscles and skin of the back. • Ventral Ramus : • Larger. • Supplies muscles and skin of the Front of the body and limbs. • Connected to theSympathetic Chainby the White and Grey Rami.

  15. SPINAL SEGMENTS AND SPINES OF VERTEBRAE • The spinal cord isSegmented. • In the Living • The approximate level of the segments is identified by thePosterior SpinousProcess of the vertebrae.

  16. SPINAL SEGMENTS AND SPINES OF VERTEBRAE • Cervical Segments: • OnespineHigherthan their corresponding vertebrae. • C7 Segment is adjacent to C6 Vertebra. • Thoracic segments : • TwospinesHigher . • Lumbar segments : • Three- FourspinesHigher.

  17. SPINAL SEGMENTS AND BODIES OF VERTEBRAE • Cervical Region : • Cervical segments lie adjacent to their correspondingVertebral Bodies.

  18. EXIT OF SPINAL NERVES • 1-7 C : Above the Upper Seven Cervical Vertebrae. • C8 : Below 7th Cervical Vertebra. • T1 and the rest of the nerves:Below their Corresponding Vertebrae.

  19. EXIT OF SPINAL NERVES • The Lumbar andSacral nerves take an Oblique Course to reach the intervertebral foramina. • The resulting leash of nerve roots forms theCauda Equina.

  20. SPINAL MENINGES • Pia Mater • The inner most layer. • A delicate ,vascular membrane. • It is Closelyapplied to the surface of the spinal cord. • It extends inferiorly as the FilumTerminale.

  21. LIGAMENTUM DENTICULATUM • A flat membrane formed from Pia Mater. • Extension: • Along a midway line between the dorsal and ventral nerve roots. • Laterally to adhere to the Arachnoid and Dura. • The spinal cord is suspended in the middle of the dural sheath.

  22. ARACHNOID & DURA • Arachnoid: • A a fibrous membrane. • It Loosely covers the spinal cord. • Dura: • A dense, strong fibrous membrane. • It is continuous superiorly with the Meningeal layer of the Cranial Dura.

  23. ARACHNOID & DURA • They extend along Each Nerve Root and become continuouswith itsEpineurium. • Inferiorly • They extend to the2nd sacral vertebra.

  24. SPACES AROUND THE CORD • Epidural • Separates Dural Sheath from the Vertebral Canal. • Contains theInternal Vertebral Venous Plexus. • Subdural • A thin space. • Separates Dura from Arachnoid.

  25. SPACES AROUND THE CORD • Subarachnoid • Contains Cerebro Spinal Fluid. • Terminates • At the level ofS2

  26. SUPPORTS OF THE CORD • Held in position by : • Laterally : DenticulateLigament. • Inferiorly : Filum Terminale. • The spinal cord is Cushioned againstTrauma by: Cerebrospinal Fluid.

  27. LUMBAR PUNCTURE • Site : • Subarachnoid Space (L2-L3 or L3 –L4). • Not Allowed in Children. • Indications: • 1. Diagnostic purposes. • 2. Radiological study (Myelography).

  28. EPIDURAL BLOCK • Injection of Anaesthetics into the Epidural Space It is for Surgical Procedures as in Labour.

  29. ARTERIAL SUPPLY • 1. Anterior spinal artery. • 2. Posterior spinal Arteries. • 3. Radicular Arteries.

  30. ANTERIOR SPINAL ARTERY A single Y shaped artery. Arises from :Vertebral arteryat the level of the medulla. • Supplies the cord at theCervical Level. • It ismost vulnerablein the anterior part of the cordparticularly in theThoracic Segment. • Its OcclusioncausesAcute Thoracic Syndrome with Paraplegia and Incontinence.

  31. POSTERIOR SPINAL ARTERIES • Two arteries. • Arise from • . Vertebral Or • Posterior Inferior Cerebellar arteries. • Spinal Arteries (Anterior &Posterior) areInsufficient aloneto supply the cord Below the Cervical Level.

  32. RADICULAR ARTERIES • Origin from following arteries : • 1. Ascending cervical 2. Intercostal. • 3. Lumbar. • They share in the arterial supply of thecord Below the Cervical Level. • They Anastomose freely with the Spinal Arteries.

  33. GREAT RADICULAR ARTERY • Artery of Adamkiewicz. • It may arise from:Intercostal or Lumbar arteries. • It supplies • Lower half ofthe spinal cord (T8 –L3). • These areVulnerable Segments. • Occlusionof the artery may cause Muscle weakness andParalysis.

  34. VENOUS DRAINAGE • Six Longitudinal Interconnecting Venous Channels. • (1) Anterior and PosteriorSpinal veins in the midline. • (2) Anterolateral and Posterolateral paired veins situated near the lines of attachment of the • Ventral and • Dorsal roots. • (3) Anterior and Posterior Radicular Veins.

  35. VENOUS DRAINAGE • (4) Internal vertebral venous plexusin the Epidural Space. • (5) External Vertebral Venous Plexus. • (6) Ascending Lumbar, Azygos and Hemiazygos Veins.

  36. SPINAL NERVE INJURY • The spinal nerve roots can be injured by Compression ofProlapsed Intervertebral Discs. • It is manifested by: • 1. Paraesthesia(tinglingsensations). • 2.Weakness and wastingof the muscles. • 3. Numbness of the skin corresponding to the dermatomal distribution. • 4. Loss of Tendon Reflexes.

  37. SITES OF DISC PROLAPSE • (A) Cervical • Pain in the neck radiating to the arm and hand. • (B) Lumbar • 1.Backpain. • 2. Sciatica ( radiation of pain into the legs) . • A large Lumbosacralprolapsed disccan cause paralysis of the bladder and incontinence.

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