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Clinical Neuroscience Week 4| 155 QUESTIONS|
WITH COMPLETE SOLUTIONS
What structures are involved in sound amplification? correct answer: -malleus -incus -stapes What structures are involved in sound dampening? correct answer: -tensor tympani: malleus -stapedius: stapes What is the labyrinth? correct answer: inner ear -cochlea, vestibule, semicircular canals What is the bony labyrinth? correct answer: -compact bone -contains perilymph that suspends membranous labyrinth What is the membranous labyrinth? correct answer: -cochlear duct, utricle, saccule, semicircular canal -filled with endolymph -hair cell receptors What is the function of hair cell receptors? correct answer: - bend and send signal frequencies to CN VIII What are the 3 hollow rings in the semicircular canals? correct answer: -anterior (superior) -lateral (horizontal) -posterior
What is the function of the receptors in the semicircular canals? correct answer: -detect motion via movement of endolymph -only sensitive to rotational acceleration and deceleration Where do the semicircular canals open into? correct answer: utricle (otolithic organ) What are ampullas? correct answer: swelling of each canal that contains a crista Describe the crista ampullaris correct answer: -supporting cells -sensory hair cells -embedded in gelatinous mass called cupula What does movement of the cupula cause? correct answer: causes hair cells to move and detect movement What are the components that make up a hair cell? correct answer: -sensory neuron -multiple small stereocilia -single large kinocilium (longest portion) When there is movement toward the kinocilium, what happens? correct answer: excitatory stimulation When there is movement away from the kinocilium, what happens? correct answer: inhibitory simulation
-bending of hairs stimulates neuronal firing frequency in CN VIII Describe the utricular macula and its max response correct answer: -resides in floor of utricle when head upright -oriented horizontally max response = head upright and bending forward (sagittal) Describe the sacular macula and its max response correct answer: -oriented vertically max response = from laterally flexed position, side lying to standing What does the vestibular system contribute to? correct answer: - head movement -head position relative to gravity -eye movement control when head moves -postural adjustments -autonomic functions What makes up the vestibular nuclei? correct answer: has superior, lateral, medial, inferior portions What does the medial vestibular and inferior vestibular nucleus portions do together? correct answer: -give rise to medial vestibulospinal tract -extends into cervical region and controls head/neck position What does the medial vestibular and superior vestibular nucleus portions do together? correct answer: -fibers ascend into the medial longitudinal fasciculus (MLF)
-oculomotor, trochlear, abducens -mediates VOR -superior colliculus and CN XI What is the vestibulo-ocular reflex (VOR)? correct answer: moves eyes in opposite direction of head movement to maintain visual stability Describe in order, an example of gaze stabilization correct answer: -rotational deceleration of head -receptors in semicircular canals -vestibular nuclei -oculomotor nuclei -extraocular muscles When he head turns right, what happens to the signal response? correct answer: -increase signal from right horizontal canal -decrease signal from left horizontal canal What components make up the eye? correct answer: cornea, sclera, iris, pupil, suspensory ligaments, ciliary body, retina What is the retina? correct answer: the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information What is the fovea? correct answer: -region of the retina with a high density of cones -provides direct access to photoreceptors without distortion
What are positive visual changes? correct answer: -light, colors, geometric shapes -retinal detachment --> light flashes -acute glaucoma --> rainbow halos around objects -migraine --> blurred vision and scotomas What are formed visual hallucinations? correct answer: -people, animals, complex scenes -arise from inferior temporo-occipital visual association cortex What are the causes of formed visual hallucinations? correct answer: -toxic/metabolic disturbances -hallucinogens, anticholinergics, cyclosporine -alcohol/sedative withdrawal -focal seizures -complex migraine -neurodegenerative conditions What are negative visual changes? correct answer: -scotoma or homonymous visual field defect -lesions in various locations in visual pathway -many see dark brown, purple, or white region in area loss What is amaurosis fugax? correct answer: -sudden, transient loss of vision in one or both eyes -"browning out" -vision loss for ~ 10 minutes What is a common cause of amaurosis fugax? correct answer: ipsilateral internal carotid artery stenosis
What is macular sparing? correct answer: -visual field loss that preserves vision in the center of the visual field -occurs because fovea represents large area of primary visual cortex (~50%) What is a contralateral homonymous hemianopia? correct answer: loss of visual information from the same visual field, right or left, in both eyes What can cause contralateral homonymous hemianopia? correct answer: infarction of entire primary visual cortex on one side results in contralateral homonymous hemianopia What is the function of the dorsal pathways for higher order visual processing? correct answer: -project to parieto-occipital association cortex -answers "where?" -analyzes motion and spatial relationships b/w objects What is the function of the ventral pathways for higher order visual processing? correct answer: -projects to occipitotemporal association cortex -answers "what?" -analyzes form -specific regions identify colors, faces, letters, and other stimuli Describe the optic nerve correct answer: -retinal ganglion cells send their axons to the optic nerve -optic nerve exits orbit through optic canal of sphenoid bone
-meningioma -trauma How is visual loss described clinically? correct answer: - described as the VISUAL FIELD affected rather than by retinal field -nasal retina = lateral field, temporal retina = medial field What occurs when there is an optic nerve lesion? correct answer: -ipsilateral blindness -loss of direct pupillary reflex -loss of pupillary light reflex What is oscillopsia? correct answer: experienced movement of the world, expected with a vestibulocerebellum lesion What disorder is commonly associated with optic nerve lesions and why? correct answer: -multiple sclerosis -because the optic nerve is myelinated by oligodendrocytes What occurs when there is an optic chiasm lesion? correct answer: -bitemporal hemianopia (loss of temporal field) -"tunnel vision" -early sign of a pituitary tumor What occurs when there is an optic tract lesion? correct answer: -homonymous hemianopia -loss of vision from same visual field in both eyes (right/right)
A complete lesion of a pathway anywhere posterior to the optic chiasm results in what? correct answer: results in loss of information from contralateral visual field What are possible causes of an optic tract lesion? correct answer: -tumor -infarct -demyelination What is Meyer's loop? correct answer: optic radiation that goes into the temporal lobe What occurs with a temporal lobe lesion? correct answer: - contralateral homonymous superior quadrantanopia -affects inferior optic radiation/Meyer's loop -"pie in the sky" What is the function of the inferior optic radiation? correct answer: -arc into temporal lobe -convey information from inferior retina and superior visual field What is the function of the superior optic radiation? correct answer: -arc into parietal lobe -convey information from superior retina and inferior visual field What occurs with a parietal lobe lesion? correct answer: - contralateral homonymous inferior quadrantanopia -affect superior optic radiations -"pie on the floor"
-association nuclei -nonspecific nuclei Describe the internal medullary lamina correct answer: -y shaped -white matter structure -intralaminar nuclei What makes up the relay nuclei? correct answer: motor: -VA, VL sensory: -VPL, VPM, medial/lateral geniculate What makes up the association nuclei? correct answer: - declarative memory (AN, LD, midline) -sensory integration (LP, pulvinar) -emotion (medial group) What makes up the nonspecific nuceli? correct answer: - intralaminar -reticular What makes up most of the thalamus? correct answer: relay nuclei What information do the lateral/medial geniculate nucleus relay? correct answer: -LGN: visual information -MGN: auditory information
Motor pathways from the cerebellum and basal ganglia project to what structures? correct answer: -VL: motor, premotor, supplementary motor cortex -VM: motor planning areas What are the functions of the hypothalamus? correct answer: - homeostasis -eating, reproductive, and defense behavior -emotional expression -circadian rhythm -endocrine regulation -SNS activation What makes up the epithalamus? correct answer: -habenula: response to odors -pineal gland: sleep/wake cycle modulation What makes up the subthalamus? correct answer: -subthalamic nuclei -parts of red nuclei -substantia nigra -ascending/descending tracts What is the function of the subthalamus? correct answer: - controlling motor function -ascending and descending tracts What is subcortical white matter? correct answer: white matter fibers that convey signals to/from the cortex
-long association Describe the cerebral cortex correct answer: vast collection of cell bodies, axons, dendrites (GM) on surface of hemispheres What are granule and pyramidal cells? correct answer: -G: small interneurons within cortex -P: output cells for cerebral cortex (projection, etc.) What are the 5 categories of the cerebral cortex? correct answer:
- primary sensory cortex
- primary motor cortex
- secondary sensory cortex
- motor planning areas
- association cortex What is the function of the primary somatosensory cortical area? correct answer: discriminates shape, texture, or size of objects What is the function of the primary auditory cortical area? correct answer: -conscious discrimination of loudness and pitch of sounds -receives information from both cochlea What is the function of the primary visual cortical area? correct answer: distinguishes intensity of light, shape, size, and location of objects What is the function of the primary vestibular cortical area? correct answer: -discriminates among head positions and head movements, contributes to perception of vertical
-receives info from vestibulothalamocortical pathway What are the effects of a lesion at the primary somatosensory cortical area? correct answer: loss of tactile localization and conscious proprioception What are the effects of a lesion at the primary vestibular cortical area? correct answer: change in awareness of head position/movement and perception of vertical What are the effects of a lesion at the primary visual cortical area? correct answer: homonymous hemianopia What are the effects of a lesion at the primary auditory cortical area? correct answer: loss of conscious localization of sounds Describe the 3 neuron pathway of the primary somatosensory cortex correct answer: -peripheral afferent/dorsal column neuron -medial lemniscus neuron -thalamocortical neuron Describe the 3 neuron pathway of the primary visual cortex correct answer: -retina -LGN -primary visual cortex What makes up the secondary sensory areas? correct answer: secondary somatosensory, visual, and auditory
What are the effects of a lesion at the primary motor cortex? correct answer: -loss of fractionated movement -spastic dysarthria What makes up the motor planning areas? correct answer: - anterior to primary motor cortex -supplementary motor area -premotor area -Broca's area What is the function of the supplementary motor area? correct answer: -initiation of movement -orientation of planning -bimanual and sequential movements What is the function of the premotor area? correct answer: - control of trunk and girdle muscles -anticipatory postural adjustment What is the function of Broca's area? correct answer: -motor programming of speech -usually in left hemisphere only What are the effects of a lesion at the supplementary motor area? correct answer: apraxia What are the effects of a lesion at the premotor area? correct answer: apraxia Define apraxia correct answer: inability to perform particular purposive actions, as a result of brain damage
What are the effects of a lesion at the Broca's area? correct answer: Broca's aphasia or difficulty producing nonverbal communication Describe the flow of cortical information from the primary sensory cortex to motor output? correct answer: -primary sensory cortex (discrim.) -secondary sensory cortex (recognize) -association cortex -motor planning areas -primary motor cortex (action) What is the function of the amygdala? correct answer: interprets other people's expressions, body language, social cues, generates feelings of fear and disgust What is cognition? correct answer: all the mental activities associated with thinking, knowing, remembering, and communicating What is emotion? correct answer: a conscious mental reaction subjectively experienced as strong feeling usually directed toward a specific object, and typically accompanied by physiological and behavioral changes in the body Describe goal oriented behavior correct answer: -cognition + emotion -decide, plan, execute, monitor
