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Central Nervous System, Spinal Nerves, And Cranial Nerves

Central Nervous System, Spinal Nerves, And Cranial Nerves. Chapter 10. Spinal Cord Structure Protection and Coverings. Spinal cord in vertebral cavity- Surrounded by bone Wrapped in meninges- 3 layers of connective tissue Spinal cord meninges are continuous with brain meninges.

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Central Nervous System, Spinal Nerves, And Cranial Nerves

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  1. Central Nervous System, Spinal Nerves, And Cranial Nerves Chapter 10

  2. Spinal Cord StructureProtection and Coverings • Spinal cord in vertebral cavity- • Surrounded by bone • Wrapped in meninges- • 3 layers of connective tissue • Spinal cord meninges are continuous with brain meninges

  3. Spinal Meninges

  4. Gross Anatomy of the Spinal cord

  5. Internal Structure of Spinal Cord

  6. Spinal Nerve Composition

  7. Distribution Of Spinal Nerves • After leaving vertebra nerves branch • Some join with axons from neighboring nerves to form plexuses • Names then relate to area they are in or region innervated • Spinal nerves T2-T11 do not form plexuses= intercostal nerves • Supply abdominal muscles, skin of chest & back and muscles between robs.

  8. Distribution of Plexuses

  9. Spinal Cord Functions • Routes signals along pathways • Gray matter integrates signals • Reflex = fast involuntary sequence of actions in response to a stimulus • Inborn reflex e.g. withdrawal reflex • Can also have learned reflexes, • e.g. driving skills • Can be spinal or cranial integration

  10. Reflex arc (patellar reflex)

  11. Brain-Major Parts

  12. Figure 10.6b

  13. (a) (b) Figure 7.11 MRI images of the brain. (a) sagittal view of brain (normal) ; (b) sagittal view of brain with a large growth in the occipital capillary bed called an arterio-venous malformation (AVM) Webster, John G., Bioinstrumentation, Wiley, Ch 7 2004

  14. Brain blood supply • Requires ~20% body’s oxygen supply • 4 min lack => permanent damage • Requires continuous glucose supply • Protected by Blood-brain barrier • Allows lipid soluble materials: O2, CO2, alcohol, anesthetic agents but controls entry of other materials • Created by tight capillaries and glial cells

  15. Cerebral Spinal Fluid (CSF)

  16. Brain Stem- Medulla • Medulla Oblongata- inferior part of brainstem • white matter extending between spinal cord & other parts of brain • several nuclei: cardiovascular center • (heart rate) • Medullary rhythmicity area • (respiratory rhythm) • Other sensory & reflex motor areas • Some related to cranial nerves

  17. Brain Stem- Pons • Pons (bridge)- nuclei & tracts • Connect left & right of cerebellum • Ascending & descending tracts • Nuclei – motor relays from cerebrum to cerebellum , respiration & cranial nerves V, VI, VII, VIII

  18. Diencephalon • Thalamus- critical relay for sensory input • Transmits motor information from cerebellum & basal nuclei to cerebrum • Hypothalamus- important for homeostasis • Control of ANS-regulation of many activities • Control of pituitary and hormone production • Regulation of emotional & behavior patterns • Regulation of eating & drinking • Control of body temperature • Regulation of circadian rhythms & states of consciousness • Pineal gland- secretes melatonin

  19. Cerebellum • Two cerebellar hemispheres • Posterior to medulla and pons, below cerebrum • Cerebellar cortex –gray matter • Tree like white matter & nuclei • Attached to brain stem via cerebellar peduncles

  20. Cerebellar function • Gets wide range of sensory input • Compares with programmed motor activity from cerebral cortex • Smoothes & coordinates complex activities • Regulates posture & balance • Required for skilled motor activities

  21. Cerebrum- Structure

  22. Cerebrum- Structure (Cont.)

  23. Limbic System • Ring of structures on inner border of cerebrum and floor of diencephalon • “emotional brain” – pain , pleasure, anger, affection, docility • Involuntary activity related to survival • Important in memory development

  24. Limbic System

  25. Function areas of Cortex • Specialized areas anatomically located • Sensory areas receive input and responsible for perception • Motor areas- initiate movements • Associative areas- complex integration: e.g. memory, emotion, reasoning, etc.

  26. Brain Area Map

  27. Sensory Pathways

  28. Sensory Pathways (cont) • Spinothalamic pathways- • anterior & lateral spinothalamic tracts • Relay impulses for pain, tickle, itch & thermal sensations.

  29. Somatic Motor Pathways

  30. Lateralization • Left gets input from & sends output to right side of body and vice versa • Left important for spoken & written language, numerical & scientific skills & reasoning • Right more involved with spatial and pattern recognition and emotional content

  31. Memory • Process for storing & retrieving information • Involves structural & functional changes • Involves association areas, parts of limbic system & diencephalon • Skill memory also involves cerebellum & basal ganglia

  32. Cranial Nerves

  33. Aging • Rapid growth during first few years • Size of neurons & proliferation of neuroglia • Increases development of dendritic branches & synaptic contacts • Decline in brain mass from early adulthood on

  34. Wrap Up!! What have we learned? • These topics fulfill some of the requirements for TCOs: • 1, 4, 6 and 7 • Major Structure and Function of CNS: • Spinal Cord • Brain • Major Pathways • Sensory • Somatic Motor • Misc • MRI of AVM • Effects of Aging

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