The Nervous Syste1

The Nervous Syste1 - arachnoid granulations in the superior...

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The Nervous System Pathways o Pathways are usually given composite names that indicate their origin and termination. Almost all ascending pathways terminate in the thalamus before projecting to the cerebrum. o The somatic motor system consists of lower and upper motor neurons. Meninges o Three connective tissue meninges cover the CNS: the dura mater, arachnoid mater, and pia mater. Ventricles o The brain and spinal cord contain fluid-filled cavities: the lateral ventricles in the cerebral hemispheres, a third ventricle in the diencephalon, a cerebral aqueduct in the midbrain, a fourth ventricle at the base of the cerebellum, and a central canal in the spinal cord. o The fourth ventricle has openings into the subarachnoid space. Cerebrospinal Fluid o Cerebrospinal fluid is formed in the choroid plexuses in the ventricles, it exits through the fourth ventricle, and it reenters the blood through
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Unformatted text preview: arachnoid granulations in the superior sagittal sinus. Peripheral Nervous System • The PNS consists of afferent and efferent fibers contained in spinal and cranial nerves. Cranial Nerves o There are 12 cranial nerves: 3 with only sensory function (S), 4 with only somatic motor function (M), 1 with motor and sensory function, 1 with somatic motor and parasympathetic (P) function, and 3 with all three functions. Four of the cranial nerves have parasympathetic function. o The cranial nerves are: olfactory (I; S), optic (II; S), oculomotor (III; M, P), trochlear (IV; M), trigeminal (V; S, M), abducens (VI; M), facial (VII; S, M, P), vestibulocochlear (VIII; S), glossopharyngeal (IX; S, M, P), vagus (X; S, M, P), accessory (XI; M), and hypoglossal (XII; M)....
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