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Neuroanatomy Part V

Neuroanatomy Part V. H. The Telencephalon: Cerebral Hemispheres. Gyri : the folds or convolutions of the cerebral cortex Sulci : the intervening grooves between the gryi on the surface of the cerebral hemispheres Fissure : a cleft that separates large components of the brain.

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Neuroanatomy Part V

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  1. Neuroanatomy Part V

  2. H. The Telencephalon: Cerebral Hemispheres Gyri: the folds or convolutions of the cerebral cortex Sulci: the intervening grooves between the gryi on the surface of the cerebral hemispheres Fissure: a cleft that separates large components of the brain

  3. A. Lobes of the Cerebral Cortex 1. Frontal 2. Parietal 3. Temporal 4. Occipital 5. Insular (island of Reil under temporal lobe) 6. Limbic

  4. The Cerebral Cortex Lobes PARETAL

  5. Sensory cortex

  6. Motor Cortex

  7. Hemisphere specialization PET scan: The brain at rest

  8. PET scan: Listening to music

  9. Circle of Willis

  10. Neurophysiology

  11. I. Neuron Excitation and Conduction ions: atoms that have either lost or gained an electron concentration gradient: a difference in the concentration of molecules on one side of a membrane from the concentration on the other side. permeability: the ease with which ions may pass through a membrane

  12. Ions can move in or out of neurons (across membranes) by passive or active mechanisms. Passive: Diffusion according to the concentration gradient Active: Ion pumps will move Na (sodium) and K (potassium) ions against the concentration gradient This sodium-potassium pump needs energy from ATP to work.

  13. Neuron at Rest At rest, there are 30 time as many K+ ions inside as outside, and 10 times as many Na+ ions outside as inside. Concentration gradient is -70 mV

  14. Action Potential: a change in electrical potential that occurs when the cell membrane is stimulated adequately to permit ion exchange.Threshold Level: a critical level which, if reached, will produce a sudden change in the membrane polarity for Na+ ions.

  15. 1. Depolarization: When the threshold level is reached, the Na+ ion gates open and allow a large number of Na+ ions to flood in and raise the intercellular potential to +30-50 mV.

  16. 2. Repolarization: During this time the K+ channels open and K+ ions go out of the intracellular space For about .5 msec, the membrane cannot be depolarized again. This is called the Absolute Refractory Period.

  17. 3. Finally, The Na+ gates will close and the sodium-potassium pump will remove most of the Na+ and increase the K+ inside the cell again.

  18. Clinical Terms

  19. Motor System Lesions Dysarthria: a speech disorder arising from paralysis, muscular weakness, and dyscoordination of speech muscles Flaccid dysarthria: muscular weakness and hypotonia arising from LMN damage (damage to cranial nerves to speech muscles) • fasciculations Spastic dysarthria: an inability to execute skilled movements and muscle weakness brought about by bilateral damage to UMN of the pyramidal and extrapyramidal pathways • hyperreflexia

  20. Hyperkinetic dysarthria: extraneous involuntary movement of speech muscles in addition to voluntary movement Hypokinetic dysarthria: lack of movement often caused by Parkinson’s. Speech will be rushed with reduced duration and intensity Apraxia: a deficit in the motor programming of articulatory movements in the absence of muscle weakness or paralysis

  21. Aphasia

  22. Aphasia Types Broca’s Aphasia: “Yes….ah…Monday…er…Dad and Peter H…and Dad…er…hospital…and ah…Wednesday…Wednesday..” Wernicke’s Aphasia: “I feel very well. My hearing, writing beendoing well. Things that I couldn’t hear from. In other words, I used to be able to wrok cigarettes I didn’t know how…Chesterfeela, for 20 years I can write it.”

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