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NERVOUS SYSTEM. STRUCTURE. NEURON pg. 148 figure 8-1. Nerve cell; specially constructed to carry out it’s function Transmitting a message from one cell to the next Extensions from the neuron are: Dendrite – may have several Axon – only one per cell Myelin sheath ( neurilemma )
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NERVOUS SYSTEM STRUCTURE
NEURONpg. 148 figure 8-1 • Nerve cell; specially constructed to carry out it’s function • Transmitting a message from one cell to the next • Extensions from the neuron are: • Dendrite – may have several • Axon – only one per cell • Myelin sheath (neurilemma) • Covering over the axon which speeds up the nerve impulse as it travels along the axon
BRAINpg. 153 figure 8-5 and 155 figure 8-7 • Weighs 3 lbs. • Coverings • Meninges – membranous coverings • Cerebral cortex – outer cortex; gray matter • Highest center of reasoning and intellect • Ventricles • 4 lined cavities filled with CSF • Cerebrum • a. Convolutions and sulci • b. Lobes • i. Frontal • ii. Parietal • iii. Occipital • iv. Temporal
Brain continuedpg. 156 figure 8-8, 158 figure 8-10, and 160 figure 8-11 • Cerebellum • Located behind the pons and below the cerebrum • Diencephalon – located b/t the cerebrum and midbrain • a. Thalamus • b. Hypothalamus • Brain stem – provides the pathway for the ascending and descending tracts • a. Midbrain • b. Pons • c. Medulla oblongata
SPINAL CORDpg. 161 figure 8-12 • Continues down from the brain • Begins at the foramen magnum of the occipital bone and continues to the second lumbar vertebra • White and soft and lies within the _________ • Made up of 31 segments • Then pair of spinal nerves • Protected by 3 layers of meninges • CSF fluid circulates over the cord
NERVESchap 9 tables 9-1 9-2 and figures 9-3 and 9-4 • Cranial nerves • 12 pairs beginning in the brain • Mainly deal with functions of the head and neck • Except vagus nerve (X) – responsible for ___ (pg. 175) • Designated by name and number • Name can give a clue to function • Spinal nerves • 31 pairs originating at the spinal cord • Exit through openings in the vertebrae • Named according to region and level they exit • Largest is the sciatic nerve