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BRAIN & CRANIAL NERVES

BRAIN & CRANIAL NERVES. The brain and spinal cord develop from ectoderm. The brain and spinal cord develop from the neural tube. Prosencephalon (Forebrain) Mesencephalon ( Midbrain) Rhombencephalon (Hindbrain) Primary brain vesicles are present around the 3rd week of development.

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BRAIN & CRANIAL NERVES

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  1. BRAIN & CRANIAL NERVES The brain and spinal cord develop from ectoderm

  2. The brain and spinal cord develop from the neural tube • Prosencephalon (Forebrain) • Mesencephalon ( Midbrain) • Rhombencephalon (Hindbrain) • Primary brain vesicles are present around the 3rd week of development

  3. Prosencephalon (forebrain) • Differentiates in 5th week into: • Telencephalon • cerebral hemispheres • Diencephalon • thalamus; hypothalamus • pineal gland

  4. Midbrain • Mesencephalon remains the same • Brainstem = midbrain

  5. Rhombencephalon • Metencephalon • cerebellum, pons • Myelencephalon • medulla oblongata

  6. Meninges • Dura mater • dural septa (extensions): falx cerebri, falx cerebelli, tentorium cerebelli • Arachnoid • Pia mater • Cavities • subarachnoid space, subdural space

  7. 4 Ventricles filled with CSF • Lateral ventricles (paired) • Interventricular foramen – connects to 3rd ventricle • Third ventricle • Cerebral aqueduct – connects 3rd and 4th ventricles • Fourth ventricle • Connects with central canal of spinal cord

  8. Cerebrospinal Fluid • Clear, colorless fluid that protects brain • Formed by the choroid plexus • Absorbed by arachnoid villi

  9. Parts of the Brain

  10. Medulla oblongata • Major reflex center for the cardiovascular and respiratory system • vasomotor, vasoconstriction • Pyramids - decussation (crossing) center for motor `tracts • Non-vital center for coughing, hiccuping, swallowing, vomiting • Ascending/descending fibers pass through • Cranial nerves VIII-XII arise here

  11. PONS • Acts as a bridge connecting the spinal cord to the brain • Major relay center for voluntary skeletal movements from the cerebral cortex to the cerebellum • Coordinates with the medulla to regulate respiration • Cranial nerves V-VIII emerge here

  12. Midbrain • Corpora quadrigemina • Visual and auditory reflex centers • Cerebral peduncles - containing large fiber tracts going to and from the brain • Houses the cerebral aqueduct • Cranial Nerves III-IV emerge here

  13. Thalamus • Two halves connected by the intermediate mass • Relay center for ALL sensory cranial and spinal nerves • Interpretation center for crude awareness of pain, temperature and pressure • Location of 3rd ventricle

  14. Hypothalamus • Links the nervous system and endocrine system • Major regulator of homeostasis • Regulates many ANS functions • Regulates appetite, water balance, thirst, body temperature • Emotional part of brain - pleasure, fear, rage

  15. Cranial Nerves • 12 Pairs • 1 Olfactory - smell • 2. Optic - sight • 3. Oculomotor - eye movements • 4. Trochlear - eye movements • 5. Trigeminal - eyes & face, chewing • 6. Abducens - eyes

  16. Cranial Nerves (continued) • 7. Facial - facial expression, taste • 8. Vestibulocochlear - equilibrium, hearing • 9. Glossopharyngeal - tonge & swallowing • 10. Vagus - heart, visceral organs • 11. Accessory - neck & back • 12. Hypoglossal - tongue

  17. Cerebellum • Second largest area of the brain • 2 cerebellar hemispheres • Arbor vitae - branchlike pattern • Vermis - wormlike structure that connects left & right side • Major coordination of skeletal muscle contraction • Assists with posture and balance

  18. Cerebrum • Cerebral cortex - outer layer of gray matter • Two hemispheres separated by longitudinal fissure • Gyri - ridges on surface • Sulci - grooves on surface • Fissures • Septum pellucidum - thin wall between ventricles

  19. Lobes of the Brain • Frontal • Parietal • Occipital • Temporal • Central sulcus • Lateral sulcus

  20. Cerebral Dominance • Left hemisphere • Language • Logic • Math • Right Hemisphere • Artistic • Musical • Creative

  21. Cerebral Cortex Specialization • Motor Areas • Control opposite side of body • Control voluntary motor functions • Sensory Areas • Detect sensations from opposite side of body • Association Areas • Integrate diverse information into purposeful action

  22. Association Areas • Prefrontal Cortex – intellect, learning, & personality • Language Areas • Wernicke’s area – sounding out new words • Brocas’s area – speech • General Interpretation • Visceral Interpretation

  23. Basal Ganglia • Cerebral nuclei • Islands of gray matter located deep within the white matter • Function: controls large automatic skeletal muscle movements and produce dopamine

  24. White Matter • Commissural fibers (corpus callosum) - connect corresponding parts of two hemispheres • Association fibers - connect within the same hemisphere • Projection fibers (higher centers to lower ones)

  25. Limbic System • Includes part of thalamus, hypothalamus, and cerebrum • Emotional brain • Associated with memory • Involuntary behavior for survival • Pleasure and pain centers - fear, sorrow, affection

  26. Reticular Formation • RAS System - reticular activating system • Network of gray matter extending from the medulla, pons, midbrain into the cortex • Maintains consciousness • Awaken from sleep • Alerts brain of incoming sensory signals

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