Cns 2


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  • key words: cerebral cortex; lobes; frontal; motor functions Frontal lobe is not directly involved in sensation or perception. Its functions are related to motor action (behavior). The motor cortex is the start of nerves that run through the spinal cord to the muscles. Broca’s area organizes sequences of speech movements. Damage leads to productive aphasia Dorsolateral Prefrontal Cortex is important in working memory. WM is short term memory for information needed to maintain a context, to prepare for the next step in a sequence of thought, and /or to inhibit irrelevant responses The wisconsin card sorting task illustrates the importance of working memory in maintaining context and inhibiting irrelevant responses
  • keywords: sympathetic nervous system; fighlt or flight response
  • key words: parasympathetic nervous system; rest and digest system
  • Cns 2

    1. 1. CNS and PNS
    2. 2. Nerve injuries types <ul><li>Neurapraxia </li></ul>Axonotmesis Neurotmesis
    3. 3. Neurapraxia <ul><li>A reversible physiological nerve conduction block in which there is loss of some types of sensation and muscle power followed by spontaneous recovery after a few days or weeks . </li></ul>
    4. 4. Axonotmesis <ul><li>It is severe form of nerve injury. The term means, literally, axonal interruption. There is loss of conduction but the nerve is in continuity and the neural tubes are intact . </li></ul>
    5. 5. Neurotmesis <ul><li>It may occur in an open wound. It is now recognized that severe degrees of damage may be inflicted without actually dividing the nerve. </li></ul><ul><li>If the injury is more severe, whether the nerve is in continuity or not, recovery will not occur. </li></ul>
    6. 6. Classification of Nerve injury <ul><li>I </li></ul><ul><ul><li>Endoneurium in tact = neuropraxia, quick recovery </li></ul></ul><ul><li>II </li></ul><ul><ul><li>Axon lesion within intact endoneurium = axonotmesis </li></ul></ul><ul><ul><li>Wallerian degeneration </li></ul></ul><ul><ul><li>Complete regeneration </li></ul></ul><ul><li>III </li></ul><ul><ul><li>Axon injury with endoneural injury </li></ul></ul><ul><ul><li>Complete loss of motor and sensory </li></ul></ul><ul><ul><li>Recovery is delayed, variable </li></ul></ul><ul><ul><li>More proximal injury, worse prognosis </li></ul></ul><ul><li>IV </li></ul><ul><ul><li>Injury to axon, endoneurium, and perineurium </li></ul></ul><ul><ul><li>Complete loss of motor and sensory </li></ul></ul><ul><ul><li>Recovery requires surgical repair, otherwise poor prognosis </li></ul></ul><ul><li>V </li></ul><ul><ul><li>Injury of axon to epineurium </li></ul></ul><ul><ul><li>Must have surgical repair </li></ul></ul>
    7. 7. Regeneration of Nerve Fibers <ul><li>Damage to nerve tissue is serious because mature neurons are amitotic </li></ul><ul><li>If the soma of a damaged nerve remains intact, damage can be repaired </li></ul><ul><li>Regeneration involves coordinated activity among: </li></ul><ul><ul><li>Macrophages – remove debris </li></ul></ul><ul><ul><li>Schwann cells – form regeneration tube and secrete growth factors </li></ul></ul><ul><ul><li>Axons – regenerate damaged part </li></ul></ul>
    8. 8. Regeneration of Nerve Fibers
    9. 9. NERVOUS SYSTEM <ul><li>Central Nervous System </li></ul><ul><ul><li>Brain </li></ul></ul><ul><ul><li>Spinal Cord </li></ul></ul><ul><li>Peripheral Nervous System </li></ul><ul><li>Somatic nerves </li></ul><ul><ul><li>Cranial Nerves </li></ul></ul><ul><ul><li>Spinal Nerves </li></ul></ul><ul><li>Autonomic nerves </li></ul>
    10. 10. CENTRAL NERVOUS SYSTEM (CNS) A HIERARCHY OF DOMAINS SPINAL CORD HINDBRAIN metencephalon mesencephalon FOREBRAIN MIDBRAIN lower -------------------------------- higher diencephalon telencephalon myelencephalon cervical MIDBRAIN NUCLEI CEREBELLUM PONS MEDULLA thoracic lumbar sacral CEREBRAL CORTEX BASAL FOREBRAIN HIPPOCAMPUS THALAMUS HYPOTHALAMUS
    11. 11. Cerebrum <ul><li>Largest portion of brain (80% mass). </li></ul><ul><li>Responsible for higher mental functions. </li></ul><ul><li>Corpus callosum: </li></ul><ul><ul><li>Major tract of axons that functionally interconnects right and left cerebral hemispheres. </li></ul></ul>Figure 8-6
    12. 12. Occipital Lobe <ul><li>Input from Optic nerve </li></ul><ul><li>Contains primary visual cortex </li></ul><ul><ul><li>most is on surface inside central fissure </li></ul></ul><ul><li>Outputs to parietal and temporal lobes </li></ul>Occipital Lobe Visual Lobe
    13. 13. Temporal Lobe <ul><li>Inputs are auditory, visual patterns </li></ul><ul><ul><li>speech recognition </li></ul></ul><ul><ul><li>face recognition </li></ul></ul><ul><ul><li>word recognition </li></ul></ul><ul><ul><li>memory formation </li></ul></ul><ul><li>Outputs to limbic System, basal Ganglia, and brainstem </li></ul><ul><li>Contains primary auditory cortex </li></ul>Temporal Lobe Temporal Lobe Auditory Cortex
    14. 14. Parietal Lobe <ul><li>Inputs from multiple senses </li></ul><ul><ul><li>contains primary somatosensory cortex </li></ul></ul><ul><ul><li>borders visual & auditory cortex </li></ul></ul><ul><li>Outputs to Frontal lobe </li></ul><ul><ul><li>hand-eye coordination </li></ul></ul><ul><ul><li>eye movements </li></ul></ul><ul><ul><li>attention </li></ul></ul>Parietal Lobe Somatosensory Cortex
    15. 15. Frontal Lobe <ul><li>Contains primary motor cortex </li></ul><ul><li>No direct sensory input </li></ul><ul><li>Important planning and sequencing areas </li></ul><ul><li>Broca’s area for speech </li></ul><ul><li>Prefrontal area for working memory </li></ul>Frontal Lobe Motor Cortex Motor Cortex Broca’s Area Motor Cortex Working Memory
    16. 17. Gross Anatomy of the Spinal Cord <ul><li>Adult </li></ul><ul><ul><li>About 18 inches (45 cm) long </li></ul></ul><ul><ul><li>1/2 inch (14 mm) wide </li></ul></ul><ul><ul><li>Ends between vertebrae L1 and L2 </li></ul></ul><ul><li>Bilateral Symmetry </li></ul><ul><ul><li>Grooves divide the spinal cord into left and right </li></ul></ul><ul><ul><li>Posterior median sulcus : on posterior side </li></ul></ul><ul><ul><li>Anterior median fissure : deeper groove on anterior side </li></ul></ul>
    17. 18. 31 Spinal Cord Segments <ul><li>Based on vertebrae where spinal nerves originate </li></ul><ul><li>Positions of spinal segment and vertebrae change with age </li></ul><ul><li>Roots </li></ul><ul><ul><li>2 branches of spinal nerves: </li></ul></ul><ul><ul><ul><li>ventral root : contains axons of motor neurons </li></ul></ul></ul><ul><ul><ul><li>dorsal root : contains axons of sensory neurons </li></ul></ul></ul><ul><ul><li>Dorsal root ganglia : contain cell bodies of sensory neurons </li></ul></ul>
    18. 19. <ul><li>The Spinal Nerve </li></ul><ul><ul><li>Each side of spine: dorsal and ventral roots join and form a spinal nerve </li></ul></ul><ul><li>Mixed Nerves </li></ul><ul><ul><li>Carry both afferent (sensory) & efferent (motor) fibers </li></ul></ul><ul><ul><li>Spinal nerves are mixed nerves </li></ul></ul>
    19. 20. Spinal Meninges <ul><li>Specialized membranes isolate spinal cord from surroundings </li></ul><ul><li>Spinal meninges: </li></ul><ul><ul><li>protect spinal cord </li></ul></ul><ul><ul><li>carry blood supply </li></ul></ul><ul><ul><li>continuous with cranial meninges </li></ul></ul><ul><li>Meningitis: </li></ul><ul><ul><li>viral or bacterial infection of meninges </li></ul></ul>Figure 13–3 <ul><li>The 3 Meningeal Layers </li></ul><ul><ul><li>Dura mater : outer layer of spinal cord </li></ul></ul><ul><ul><li>Arachnoid mater : middle meningeal layer </li></ul></ul><ul><ul><li>Pia mater : inner meningeal layer </li></ul></ul>
    20. 21. Cerebrospinal Fluid (CSF) <ul><li>Is found in subarachnoid space </li></ul><ul><li>Carries dissolved gases, nutrients, and wastes </li></ul><ul><li>Spinal tap : </li></ul><ul><ul><li>withdraws CSF </li></ul></ul>
    21. 22. Sectional Anatomy of the Spinal Cord <ul><li>Is superficial </li></ul><ul><li>Contains myelinated and unmyelinated axons </li></ul>White Matter Gray Matter <ul><li>Surrounds central canal of spinal cord </li></ul><ul><li>Contains neuron cell bodies, neuroglia, unmyelinated axons </li></ul><ul><li>Has projections ( gray horns ) </li></ul>
    22. 23. <ul><li>Gray matter: mostly cell bodies </li></ul><ul><ul><li>Dendrites & terminals </li></ul></ul><ul><ul><li>Spinal reflex integrating center </li></ul></ul><ul><li>White matter </li></ul><ul><ul><li>Bundles of myelinated axons </li></ul></ul><ul><ul><ul><li>Ascending tracts – sensory </li></ul></ul></ul><ul><ul><ul><li>Descending tracts – motor </li></ul></ul></ul><ul><ul><li>Dorsal roots </li></ul></ul><ul><ul><li>Ventral roots </li></ul></ul>Spinal Cord Organization
    23. 24. <ul><ul><li>Posterior gray horns : contain somatic and visceral sensory nuclei </li></ul></ul><ul><ul><li>Anterior gray horns : contain somatic motor nuclei </li></ul></ul><ul><ul><li>Lateral gray horns : are in thoracic and lumbar segments and contain visceral motor nuclei </li></ul></ul>
    24. 25. Organization of White Matter <ul><li>3 columns (funiculi) on each side of spinal cord: </li></ul><ul><ul><li>posterior white columns </li></ul></ul><ul><ul><ul><li>Lie between posterior gray horns and posterior median sulcus </li></ul></ul></ul><ul><ul><li>anterior white columns </li></ul></ul><ul><ul><ul><li>Lie between anterior gray horns and anterior median fissure </li></ul></ul></ul><ul><ul><ul><li>Area where axons cross from 1 side of spinal cord to the other </li></ul></ul></ul><ul><ul><li>lateral white columns </li></ul></ul><ul><ul><ul><li>Located on each side of spinal cord </li></ul></ul></ul><ul><ul><ul><li>Between anterior and posterior columns </li></ul></ul></ul>
    25. 26. Spinal Cord Organization Specilization in the spinal cord
    26. 27. Peripheral nervous system <ul><ul><li>I Somatic nervous system </li></ul></ul><ul><ul><li>Cranial Nerves </li></ul></ul><ul><ul><li>Spinal Nerves </li></ul></ul><ul><ul><li>II Autonomic nervous system </li></ul></ul><ul><ul><li>Sympathetic nerves </li></ul></ul><ul><ul><li>Parasympathetic nerves </li></ul></ul>
    27. 28. <ul><li>Peripheral nervous system (PNS) </li></ul><ul><ul><li>Outside the CNS </li></ul></ul><ul><ul><li>Nerves extending from brain and spinal cord </li></ul></ul><ul><ul><ul><li>Cranial nerves </li></ul></ul></ul><ul><ul><ul><li>Spinal nerves </li></ul></ul></ul><ul><ul><li>Link all regions of the body to the CNS </li></ul></ul>
    28. 29. Somatic vs. Autonomic <ul><li>Voluntary </li></ul><ul><li>Skeletal muscle </li></ul><ul><li>Single efferent neuron </li></ul><ul><li>Axon terminals release acetylcholine </li></ul><ul><li>Always excitatory </li></ul><ul><li>Controlled by the cerebrum </li></ul><ul><li>Involuntary </li></ul><ul><li>Smooth, cardiac muscle; glands </li></ul><ul><li>Multiple efferent neurons </li></ul><ul><li>Axon terminals release acetylcholine or norepinephrine </li></ul><ul><li>Can be excitatory or inhibitory </li></ul><ul><li>Controlled by the homeostatic centers in the brain – pons, hypothalamus, medulla oblongata </li></ul>
    29. 31. Sympathetic <ul><li>“ Fight or flight” response </li></ul><ul><li>Release adrenaline and noradrenaline </li></ul><ul><li>Increases heart rate and blood pressure </li></ul><ul><li>Increases blood flow to skeletal muscles </li></ul><ul><li>Inhibits digestive functions </li></ul>CENTRAL NERVOUS SYSTEM Brain Spinal cord SYMPATHETIC Dilates pupil Stimulates salivation Relaxes bronchi Accelerates heartbeat Inhibits activity Stimulates glucose Secretion of adrenaline, nonadrenaline Relaxes bladder Stimulates ejaculation in male Sympathetic ganglia Salivary glands Lungs Heart Stomach Pancreas Liver Adrenal gland Kidney
    30. 32. Parasympathetic <ul><li>“ Rest and digest ” system </li></ul><ul><li>Calms body to conserve and maintain energy </li></ul><ul><li>Lowers heartbeat, breathing rate, blood pressure </li></ul>CENTRAL NERVOUS SYSTEM Brain PARASYMPATHETIC Spinal cord Stimulates salivation Constricts bronchi Slows heartbeat Stimulates activity Contracts bladder Stimulates erection of sex organs Stimulates gallbladder Gallbladder Contracts pupil
    31. 33. Spinal Nerves <ul><li>31 pairs – contain thousands of nerve fibers </li></ul><ul><li>Connect to the spinal cord </li></ul><ul><li>Named for point of issue from the spinal cord </li></ul><ul><ul><li>8 pairs of cervical nerves (C 1 -C 8 ) </li></ul></ul><ul><ul><li>12 pairs of thoracic nerves (T 1 -T 12 ) </li></ul></ul><ul><ul><li>5 pairs of lumbar nerves (L 1 -L 5 ) </li></ul></ul><ul><ul><li>5 pairs of sacral nerves (S 1 -S 5 ) </li></ul></ul><ul><ul><li>1 pair of coccygeal nerves (Co 1 ) </li></ul></ul>
    32. 34. Cranial Nerves The Cranial Nerves