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The Central Nervous System

The Central Nervous System - to grow over&amp...

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The Central Nervous System Embryonic Development: at 3 weeks, neural plate forms from ectoderm - neural plate folds on itself to form neural tube - the anterior end of the neural tube expands to form the 3 primary brain vesicles: the forebrain, the mesencephalon (midbrain) & the rhombencephalon (hindbrain) - the remaining posterior end of the neural tube forms the spinal cord - expansions of the lumen of the neural tube form the brain ventricles - at week 5, further development of the primary vesicles gives rise to the secondary vesicles: o the forebrain divides into the telencephalon & diencephalons the telencephalon forms the cerebral hemispheres (cerebrum) the diencephalons forms the hypothalamus, thalamus & epithalamus o the hindbrain divides into the metencephalon & myelencephalon the metencephalon forms the cerebellum & pons the myelencephalon forms the medulla oblongata o the midbrain remains undivided - later in development, the brain outgrows the skull, causing the cerebral hemispheres
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Unformatted text preview: to grow over & enclose the diencephalons & midbrain- by week 26, continued growth of the cerebrum causes its surfaces to crease & fold into convolutions Brain Regions:- cerebral hemispheres- brain stem : inferior portion; continuous with spinal cord o midbrain, pons & medulla oblongata- diencephalon : superior to brain stem o thalamus, hypothalamus, epithalamus & subthalamus- cerebellum: posterior to brain stem Ventricles of Brain:- lateral ventricles: deep within cerebral hemispheres, separated anteriorly by the septum pellucidum- third ventricle: in diencephalon; communicates with lateral ventricles via the intraventricular foramen- fourth ventricle: in hindbrain; continuous with third ventricle via the cerebral aqueduct (in midbrain)- apertures (openings) in the walls of the fourth ventricle connect the ventricles with the subarachnoid space surrounding the brain- the ventricles & subarachnoid space are filled with cerebrospinal fluid Page1...
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