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54 Cards in this Set
- Front
- Back
two important functions of spinal cord and spinal nerves
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pathways for sensory and motor impulses and responsible for reflexes
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spinal cord structure
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42-45cm; roughly cylindrical - slightly flattened on ea. side; 2 longitudinal depressions - posterior and anterior median fissure; cord is shorter than the vertebral canal
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regions of the spinal cord
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cervical, thoracic, lumbar, sacral, coccygeal
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conus medullaris
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tapering inferior end of the spinal cord; marks the official end of the spinal cord proper
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cauda equina
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inferior to conus medullaris, nerve roots that project inferiorly from the spinal cord
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filum terminale
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with the cauda equina; thin strand of pia mater that helps anchor the conus medularis to the coccyx
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spinal nerves
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31 pairs assoc w/spinal cord that connect the CNS to muscles, receptors and glands; each side has 8C, 12T, 5L, 5S, 1Co
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gray matter location/distribution in spinal cord
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centrally located, letter H or a butterfly; anterior horns, lateral horns, posterior horns; gray commissure
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white matter location/distribution in spinal cord
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external to gray matter; 3 regions: posterior funiculus -
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dermatome
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specific segment of skin supplied by a single spinal nerve; all spinal nerves but C1 innervate a segment of skin - assoc w/ a dermatome
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intercostal nerves
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anterior rami of T1-T11; travel in the intercostal space sandwiched b/w two adjacent ribs
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nerve plexuses
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network of interweaving anterior rami of spinal nerves; split into multiple named nerves that innervate the body; cervical plexuses, brachial plexuses, lumbar plexuses, sacral plexuses
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cervical plexus
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anterior rami of C1-C4; innervates skin an muscles of neck area
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brachial plexus
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C5-T1; innervates upper limb
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reflexes
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rapid, automatic, involuntary rxns of muscles or glands to a stimulus
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properties of reflexes
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stimulus req'd; rapid response requires that few neurons be involved and synaptic delay be minimal; automatic response occurs the same way every time
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components of a reflex arc
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the neural wiring of a single reflex
always begins at a receptor in PNS communicates w/CNS ends at a peripheral effector cell |
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ipsilateral reflex arc
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both the receptor and effector organs of the reflex are on the same side of the spinal cord
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contralateral reflex
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when the sensory impulses from a receptor organ cross over through the spinal cord to activate effector organs in the opposite limb
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monosynaptic reflex
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simplest; interneurons not involved; patellar reflex - used to assess functioning of the spinal cord
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polysynaptic reflexes
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more complex neural pathways that exhibit a number of synapses involving interneurons within the reflex arc; longer delay b/w stimulus and response
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stretch reflexes
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monosynaptic reflex that monitors and regulates skeletal muscle length; patellar reflex; when stimulus results in the stretching of a muscle that muscle reflexively contracts
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golgi tendon reflex
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prevents skeletal muscles from tensing excessively; Golgi tendon organs are nerve endings located w/in tendons near a muscle-tendon junction;
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ganglion
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cluster of neuron cell bodies within the PNS
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center
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group of CNS neuron cell bodies with a common function
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nucleus
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center that displays discrete anatomic boundaries
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nerve
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axon bundle extending through the PNS
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nerve plexus
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network of nerves
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tract
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CNS axon bundle in which the axons have similar function and share a common origin and destination
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funiculus
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group of tracts in a specific area of the spinal cord
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pathway
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centers and tracts that connect the CNS with body organs and systems
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ascending pathways
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carry sensory info from the peripheral body to the brain
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descending pathways
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transmit motor info from the brain or brainstem to muscles or glands
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somatotopy
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pathways that connect parts of the primary motor cortex to a specific body part
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All pathways are composed of _____ tracts.
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paired
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pathways are composed of how many neurons working together?
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2 or 3
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sensory pathways
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have primary, secondary and sometimes tertiary neurons that facilitate the pathway's functioning
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motor pathways
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use an upper motor neuron and lower motor neuron; cell bodies are located in the nuclei associated with each pathway
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sensory pathways conduct info about
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limb position and the sensations of touch, T, P, and pain
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somatosensory pathways process stimuli received from
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receptors within the skin, muscles and joints
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primary (first order) neurons
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first neuron in sensory pathway; dendrites are part of the receptor that detects a specific stimulus; cell body is in posterior root ganglia of spinal nerves or the sensory ganglia of cranial nerves
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secondary (second-order) neuron
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interneuron; in either posterior horn of the spinal cord or a brainstem nucleus; axon projects to the thalamus, where it synapses with the tertiary neuron
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tertiary neuron
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interneuron; cell body in thalamus; thalamus is central processing and coding center for almost all sensory information
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posterior funiculus-medial lemniscal pathway
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projects through spinal cord (PF), brainstem (ML) and diencephalon before terminating within the cerebral cortex; sensory stimuli concerned with proprioceptive info about limb position and discriminative touch, pressure, and vibration sensations
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anterolateral pathway
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located in the anterior and lateral white funiculi of the spinal cord; anterior and lateral spinothalamic tract; crude touch and pressure, pain and temp;
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spinocerebellar pathway
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conducts proprioceptive info to cerebellum for processing to coordinate body movements; composed of anterior and posterior spinocerebellar tracts; different from other sensory pathways in that they do not use tertiary neurons
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motor pathways
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descending pathways in the brain and spinal cord that control the activities of skeletal muscle; formed form cerebral nuclei, cerebellum, descending projection tracts and motor neurons
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corticobulbar tracts
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transmit motor info to control the cranial nerves; descend from the cerebral cortex through the brainstem and form a pair of thick bulges in the medulla called the pyramids
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cerebral cortex
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higher order mental functions: consciousness, learning, memory, and reasoning;
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cerebral lateralization
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each hemisphere tends to be specialized for certain tasks; higher order centers in both hemispheres tend to have different but complementary functions
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cerebral lateralization
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each hemisphere tends to be specialized for certain tasks; higher order centers in both hemispheres tend to have different but complementary functions
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left hemisphere
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categorical hemisphere; categorization and symbolization; contains Wernicke's area and the motor speech area; language; sci/math; controls speech in most ppl
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Right hemisphere
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representational hemisphere; visuospatial relationships and analyses; imagination, perception, spatial relationships, sights, sounds, smells, tastes
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hemispheres remain in contact through ______
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commissures, esp the corpus callosum, which contain a ton of axons projecting b/w the hemispheres
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