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bioltest2review - Chapter 12 General Organization of the...

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Unformatted text preview: Chapter 12 General Organization of the Nervous System o Central Nervous System Brain and Spinal Cord Collection of neural cell bodies with a common function called a center With a discrete anatomical boundary: Nucleus Higher centers: most complex integration centers, nuclei, and cortical areas of brain Portions of the brain surface are covered by a thick layer of gray matter called neural cortex White matter contains bundles of axons that share common origins, destinations, and functions Organized into tracts Tracts form columns Centers and tracts are called pathways Sensory pathways: distribute information from peripheral receptors to processing centers of the brain Motor pathways: begin at CNS centers concerned with motor control and end at effectors they control o Peripheral Nervous System Other neural tissue in body (nerves) Neuron cell bodies located in ganglia Spinal nerves : connected to spinal cord Cranial nerves : connected to brain Gross Anatomy of the Spinal Cord o Posterior median sulcus : shallow longitudinal groove o Anterior median fissure : deeper groove along ventral surface o Enlargements : Expanded areas of gray matter in places that deal with sensory and motor control Cervical enlargement : supplies nerves to shoulder girdles and upper limbs Lumbar enlargement : provides innervation to structures of the upper and lower limbs o Conus medullaris : area inferior to the lumbar enlargement where spinal cord becomes tapered and conical o Filum terminale : slender strand of fibrous tissue that extends from inferior tip of conus medullaris; provides longitudinal support to spinal cord as a component of coccygeal ligament o Dorsal root ganglia : groups of cell bodies of sensory neurons; every spinal segment is associated with one of these Dorsal roots : axons of neurons that bring sensory information into the spinal cord Ventral roots : axons of motor neurons that extend into periphery to control somatic and visceral effectors On both sides, dorsal and ventral roots pass through intervertebral foramen o Spinal nerve: where sensory and motor roots are bound together distal to each dorsal root ganglion; are mixed nerves Mixed nerves: contain both afferent (sensory) and efferent (motor) fibers; 31 pairs of spinal nerves Notes about spinal nerves: in thoracic and lumbar sections, they are named for the vertebra superior to it (i.e. nerve T1 is inferior to vertebra T1). In the cervical region, they are named for the vertebra inferior to it. Thus there are 8 cervical nerves but only 7 vertebrae, to make up for the extra one. o Spinal cord growth: continues to grow until about 4 years of age....
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bioltest2review - Chapter 12 General Organization of the...

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