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34 Cards in this Set
- Front
- Back
What are the three pure sensory cranial nerves? What are these cranial nerves responsible for?
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Cranial Nerves 1, 2, and 8; Olfactory Nerve, Optic Nerve, Vestibular Cochlear Nerve; These nerves are concerned with SPECIAL SOMATIC SENSES
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What is cranial nerve 1 responsible for?
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Olfactory Nerve; Special somatic sensory; smell
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How is CN1 different from the other CNs in structure?
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The olfactory nerve does not contain a single bundle of axons, but rather 20 or so separate bundles arising from olfactory cells scattered along the epithelial cells in the nasal cavity; note that the olfactory nerve is the only nerve that does not attach to the brainstem (attaches to telencephalon)
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What type of neurons are the olfactory nerves?
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Bipolar neurons; their processes merge to make a plexiform network, which give rise to bundles of nerves, which in turn give rise to olfactory nerve, proper
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Describe the passage of the olfactory nerve through the skull (CN1)
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Through the cribiform plate--> piece of ethmoid bone-->through dura and arachnoid-->olfactory bulb-->synapse at mitral cells-->olfactory tracts-->telencephalon
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What can cause a loss of smell?
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Breakage of the olfactory bulbs; unbalanced degeneration of olfactory cells at 1% each year (usually regenerate)
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What is the function of CN II?
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CN II= optic nerve; special somatic sensory nerve = vision
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Describe the origin of CN II and its passage through the skull
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Nerve begins at retina at back of eyeball-->converges at optic disk to become continuous with optic nerve (at optic chiasma)-->fibers continue to thalamus or midbrain (lateral geniculate ganglion or superior colliculi ganglion)--> pass to occipital cortex where visual impulses are decoded
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Why is the optic nerve surrounded by meninges?
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Because it originates at the retina, which is an outgrowth of the brain
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What types of cells lengthen to form rods and cones?
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Bipolar cells; ganglion cells synapse at bipolar cells
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What is the effect of having lateral fibers stay on the same side after the nerve fibers cross at the optic chiasma?
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Neurons in related visual field are carried in the same optic tract
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Describe the movement of the CNII fibers after they converge to form the optic nerve
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Medial fibers cross to opposite side and lateral fibers stay on the same side at the optic chiasma
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What is the function of CNVIII
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Vestibular Cochlear Nerve; responsible for hearing and balance; special somatic sensory nerve
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Where does CNVIII originate? Trace its path through the skull
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Originates from cochelar ganglion and vestibular ganglion-->fibers converge and pass through internal acoustic meatus-->pass through posterior cranial fossa and enters pons and medulla; n.b. CN VIII NEVER exits the skull (unique)- stays in petrous temporal bone
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What is the location of the vestibular ganglion?
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The semicircular canals
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Where are the cell bodies of CNI?
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Nasal mucosa
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Where are the cell bodies of CN II?
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Retina
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Where are the cell bodies of CNVIII
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Vestibular ganglion (semicircular canals); spiral ganglion (cochlea)
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What structures pass through the superior orbital fissure?
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Oculomotor (3), Trochlear (4), Trigeminal-opthalmic nerve (V1), Abducens (6); superior opthlamic vein
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What structure passes through the foramen spinosum?
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The middle meningeal artery
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What structure(s) pass through the internal acoustic meatus?
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Facial Nerve (CN7); Vestibulocochlear nerve (CN8)
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What structure(s) pass through the hypoglossal canal?
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CN12; hypoglossal nerve
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What structure(s) pass through the foramen magnum?
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The spinal cord and vertebral arteries
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What structure(s) pass through the foramen cecum?
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The emissary veins to the superior saggital sinus
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What structure(s) pass through the cribiform plate?
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The olfactory nerve=CNI
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What structure(s) pass through the optic canal?
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CN 2 (optic nerve) and opthlamic artery
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What structure(s) pass through the foramen rotundum?
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The trigeminal nerve (CNV2)- maxillary nerve
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What structure(s) pass through the foramen ovale?
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The mandibular nerve (CNV3)
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What structure(s) pass through the foramen lacerum?
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The internal carotid artery
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What structure(s) pass through the jugular foramen?
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The internal jugular vein, CN 9 (glossopharyngeal), CN 10 (vagus) and CN XI (accessory)
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What are the two types of vestibular sensory fibers of CNVIII?
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1) Fibers that detect static equilibrium (from sacculus and utricle); 2) Fibers that detect dynamic equilibrium (semicircular canals)
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What embryonic region does CNI originate from?
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The CNS = ectoderm
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What embryonic region does CNII originate from?
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Diencephalon
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What embryonic region does CNVIII originate from?
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Metencephalon
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