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The Spinal Cord

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  1. The Spinal Cord Honors Anatomy& Physiology for copying

  2. Spinal Cord w/spinal nerves contain neural circuits that mediate some of your most rapid reactions to environmental changes

  3. Protective Structures 2 types of CT coverings surround & protect delicate nervous tissue bony vertebrae tough CT meninges, w/cushion of CSF

  4. Meninges 3 CT coverings that encircle spinal cord & brain: Spinal meninges covers spinal cord Cranial meninges covers brain

  5. Meninges Layers: Dura Mater “tough mother” most superficial layer made of dense, irregular CT continuous with cranial meninges forms sac from foramen magnum  S2 layer of adipose tissue between dura mater & wall of vertebral cavity (epidural space)

  6. Middle Meninges: Arachnoid Mater “spider-like” deep to dura mater, superficial to pia mater contiguous with cranial arachnoid between dura & arachnoid = subdural space

  7. Innermost Meninges:Pia mater “delicate” thin, transparent CT adheres to spinal cord & brain between arachnoid & pia = subarachnoid space

  8. Spinal Tap • aka lumbar puncture • long needle inserted into subarachnoid space • adults: between L3 –L4 or L4 – L5 (inferior to lowest portion of spinal cord) • purpose: withdraw CSF for • diagnostic purposes • insert antibiotics/contrast media for myelography/ anesthetics/ chemotherapy

  9. Spinal Cord cylindrical with flattening of its AP diameter adults:extends from medulla oblongata  L2 vertebra newborns: extends to L3 or L4 elongation of spinal cord stops ~age 3-4 but growth of vertebral column continues

  10. Spinal Cord: External View • 2 obvious enlargements noted: • cervical enlargement • C4 – T1 • serve upper limbs • lumbar enlargement • T9- T12 • serve lower limbs

  11. Spinal Cord: External View conusmedullaris: tapered conical structure of spinal cord below lumbar enlargement ending @ L1 – L2 filumterminale: extension of pia mater extends inferiorly & anchors cord to coccyx caudaequinae: “horse tail” nerves that arise from lumbar, sacral, & coccygeal portions of spine

  12. Spinal Nerves 31 pairs spinal nerves emerge thru intervertebral foramen 8 pair cervical nerves: C1 – C8 12 pair thoracic nerves: T1 - T12 5 pair lumbar nerves: L1 – L5 5 pair sacral nerves: S1 – S5 1 pair coccygeal nerves: Co1

  13. Spinal Nerves 2 bundles of axons, called roots, connect each spinal nerve to segment of spinal cord

  14. Spinal Cord Roots • posterior (dorsal) root • only sensory axons • each has dorsal root ganglion containing cell bodies of sensory neurons • anterior (ventral) root • only motor axons

  15. Internal Anatomy of Spinal Cord • 2 grooves penetrate white matter & divide it in right & left sides: • anterior median fissure • deeper, wider of the 2 • posterior median sulcus • shallower, narrow furrow

  16. Spinal Nerves & the nerves that branch off them are part of PNS emerge from vertebral column thru intervertebral foramina

  17. Spinal Nerves • typically has 2 connections to spinal cord • dorsal root (sensory) • ventral root (motor) • classified as “mixed”

  18. Distribution of Spinal Nerves

  19. Spinal Nerve Plexuses a network of nerves (or veins, or lymphatic vessels)

  20. Cervical Plexus supplies skin & muscles of the head, neck, & superior portion of shoulders, chest, & diaphragm C1 – C 5

  21. Brachial Plexus supplies the shoulders & upper limbs

  22. Lumbar Plexus supplies anterolateralabd wall, external genitals, part of lower limb

  23. Sacral Plexus supplies buttocks, perineum, & lower limbs

  24. Dermatomes cutaneous area developed from one embryonic spinal cord segment & receiving most of its sensory innervation from one spinal nerve knowing which spinal cord segments supply each dermatome makes it possible to locate damaged regions of the spinal cord

  25. Spinal Cord Injuries • most due to trauma • cervical, lower thoracic, upper lumbar most common regions involved • paralysis • depends on location, extent of damage • monoplegia: 1 limb • paraplegia: both lower limbs • hemiplegia: upper limb, trunk, lower limb on 1 side of body • quadriplegia: all 4 limbs & trunk

  26. Extent Muscle Paralysis C1 – C3: no function neck down, requires ventilator to breathe C4 – C5: diaphragm, allows breathing C6 – C7: some arm, chest, allows breathing, moving wheelchair T1 – T3: intact arm function T4 – T9: control of trunk above umbilicus T10 – L1: most thigh muscles, walk w/long leg braces L1 – L2: most leg muscles, walk w/short leg braces

  27. Shingles • acute infection of PNS • caused by herpes zoster (chicken pox) • virus stays in posterior root ganglion • becomes reactivated normally immune system will prevent it from spreading • reactivated virus can overcome weakened immune system  leaves ganglion  travels down sensory neurons supplying skin

  28. Medical Terminology meningitis: inflammation of meminges due to infection, bacterial (worse) or viral, vaccine protests against some bacterial causes: headache, N/V, fever, stiff neck neuralgia: pain along a sensory nerve, trigeminal neuralgia neuritis: inflammation of 1 or several nerves paresthesis: abnormal sensation