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67 Cards in this Set
- Front
- Back
Purpose of having folded pattern of cortex?
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allows for an increase in the SA of the cortical gray matter without a corresponding increase in size of the cranial vault
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Compare
Gyrus Sulcus Fissure |
Gyrus - elevation on surface of hemisphere
Sulcus - depression or groove between gyri Fissure - a large and constant sulcus may be called a fissure, but the 2 terms are sometimes used interchangeably |
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In which fissure can you visualize the insula?
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opening lateral fissure
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What are the boundaries of the frontal lobe?
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On lateral surface:
posterior boundary: central sulcus Inferior boundary: lateral sulcus On medial surface: posterior: arbitrary line from central sulcus to CC inferior: CC/cingulate gyrus (limbic lobe) |
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What are the boundaries of the parietal lobe?
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on lateral surface:
anterior: central sulcus interior: lat sulcus and an arbitrary line directed posteriorly from the lateral sulcus Posterior: upper half of an arbitrary line connecting parieto-occiptal sulcus with the pre-occipital notch Medial surface: Anterior: frontal lobe Posteror/inferior: parieto-occipitosulcus and cingulate gyrus |
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What are the boundaries of the temporal lobe?
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on lateral surface:
superior: lateral sulcus and it posterior projection posterior: lower portion of arbitrary line connecting the parieto-occital sulcus and the pre-occipital notch on medial surface: imaginary line joining the parieto-occipital sulcus and the pre-occipital notch |
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What are the boundaries of the occiptal lobe?
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lateral surface: line joining the parieto-occipital sulcus to the pre-occiptal notch
medial: posterior borders of the parietal and temporal lobes |
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4 functional groups of the cortex?
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Motor areas
Sensory areas Language areas Frontal association areas |
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General role of association areas of the cortex
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produce a meaningful perceptual experience of the world, enable us to interact effectively, and support abstract thinking and language.
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Components of the primary motor cortex
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Precentral gyrus
Bordered by: Precentral sulcus + Central sulcus |
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Consequence of lesion to primary motor area
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UMN signs
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Location of the premotor or motor association areas
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includes:
anterior part of precentral gyrus parts of sup, middle and inf frontal gyri |
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Consequences of a lesion to the premotor or motor association area
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Apraxia = deficits in learned, skilled motor activity, in absence of paralysis.
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Location of primary somatosensory area
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postcentral gyrus
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Consequence of lesion to primary somatosensory area
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- decreased awareness of sensory info
- reduced proprioception, touch and pain sensation |
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Location of the somatosensory association area
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superior parietal lobules, extending onto medial surface
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Consequence of lesion to somatosensory association area
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Tactile agnosia = Impaired ability to recognize or identify objects by touch alone.
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Location of the primary auditory area
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superior surface of superior temporal gyrus - Heschl's gyri (aka transverse temporal gyri)
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Consequences of a lesions to primary auditory area
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- subtle impairment in hearing
- cannot localize sounds - usually okay because bilateral input |
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Location of auditory association area
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superficial temporal gyrus and area posterior to primary auditory area in lateral sulcus
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Consequences of a lesions to auditory association area
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Deficit in sound interpretation (even though can hear normally)
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Location of primary visual area
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in walls of posterior part of calcarine sulcus, extending onto lateral surface
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Consequences of lesion to primary visual area
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blindness in opposite visual field
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Location of visual association area
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surround primary visual are on medial and lateral surfaces
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Consequences of lesion to visual association area
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- Visual agnosia = unable to recognize object in opposite visual field, despite intact vision
- also, deficit in pursuit or tracking in IPSILATERAL eye |
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Location of the primary taste area
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- on insula and adjacent medial surface of parietal-frontal operculum at base of centra sulcus (operculum = lid or cover, overlying cortical area)
- can be visualized deep in lateral fissure btw temporal and frontal lobes |
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Location of secondary taste area
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orbital cortex of frontal lobe and amygdala
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Function of secondary taste area
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taste information is integrated with olfactory information
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Functions of frontal association areas
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aka prefrontal cortex
- concerned with complex aspects of behaviour (ie affect, personality, attention) - extensive connection with dorsomedial (DM) nucleus of thalamus |
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Consequences of lesion to frontal association cortex
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- change in emotion, motivation, personality, initiative, judgement, conentration, social behaviour, carelessness of appearance/dress
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Location of motor speech area of broca
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part of inferior frontal gyrus of dominant hemisphere (usually left)
* upside down U shape near intersection of premotor area and lateral sulcus |
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Function of broca's area
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expression of speech
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Consequences of lesion to broca's area
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Nonfluent aphasia:
- cannot get words out properly even though normal comprehension - aware of problem |
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Location of sensory speech are of Wernicke
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- posterior part of the superior temporal gyrus, with extensions around the posterior end of the lateral sulcus into the parietal region (DOMINANT hemisphere - usually in left)
* armpit of lateral fissure |
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Function of wernicke's area
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reception of speech (comprehension)
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Consequences of lesion to wernicke's area
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Fluent aphasia
speech fluent but nonsensical - usually unaware of the problem |
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Consequence of lesion to language are of NON dominant hemisphere
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Aprosodia
= deficit in intonative, rhythm |
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Types of association fibers
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Short: connect cortical areas in adjacent gyri
Long: pass bw cortical areas that are further removed from each other |
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Superior longitudinal fasciculus
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aka arcuate fasciculus (because arches over lateral fissure)
- located above the insula - connects: frontal <-> parietal <-> temporal lobes - connects wernickes and broca's areas |
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Consequence of lesion to arcuate fasciculus to speech
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Conduction aphasia
Speech fluent but paraphasia word substitutions errors (ex treen instead of train) * due to sensory from broca not being properly passed to broca |
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Inferior occipitofrontal fasciculus
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- runs below insula
- connects: frontal <-> temporal <-> occipital lobes |
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Unicate fasciculus
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- part of inferior occipitofrontal fasciculus
- connect frontal and temporal lobe |
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Superior occipitofrontal fasciculus
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- fibers fun adjacent and perpendicular to corpus collosum along most of its course
- connect: occipital and frontal lobes |
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Cingulum
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- runs beneath cingulate gyrus and parahippocampal gyrus
- connects areas of limbic cortex with each other` |
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Commisural fibers
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- connect R and L hemispheres
- largest one: corpus collosum |
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Connections made with body of CC
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parietal lobes
posterior part of 2 frontal lobes |
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Connections made with splenium of CC
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connects occipital lobes
posterior temporal lobes |
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Connections made with genu of CC
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fibers originating in or proceeding to frontal areas
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Connections made with rostrum of CC
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thin shelf of fibers projecting backwards in genu
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Connection made within radiations of CC
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fibers fan out as they project to all parts of cortex
forceps minor : at anterior end foreceps major : at posterior end |
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Anterior commissure
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connects:
two anterior temporal lobes and olfactory bulbs |
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Posteior commissure
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connects the two pretectal nuclei
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Projection fibers
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thalamus <-> cortex
descending fibers to: striatum, brainstem and spinal cord |
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Internal capsule
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compact bundle formed from gathering of projection fibers
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Limbs of internal capule
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anterior limb: cuts bw head of caudate and lenticular nucleus
posterior limb: cuts bw thalamus and lenticular nucleus Genu = where two limbs meet |
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What is the lenticulate nucleus?
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= putamen + globus pallacius
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Location of basal nuclei and thalamus in relation to internal capsule
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- caudate nucl. and thalamus always medial
- palladium and putamen always lateral |
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What type of information is processed by the thalamus?
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- all sensory information (except olfaction)
- basal ganglia - cerebellum |
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Major sensory relay nuclei of the thalamus + functions
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- Ventral posterior (VPL, VPM) = somatosensory
- Medial geniculate nucleus (MGN) = hearing - Lateral geniculate nucleus ( LGN) - vision |
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Major motor nuclei of the thalamus and their functions
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- ventral lateral (VL)
- Ventral anterior (VA) * connect with basal ganglia and cerebellum |
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Thalamic Limbic nuclei ?
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Limbic nuclei in anterior thalamus connects with cingulate gyrus
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MCA supplies..
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most of lateral surface of the brain
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ACA supplies..
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medial surface of frontal and parietal lobes
* overlap onto lateral surface and supply thin border of the cortex |
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PCA supplies...
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medial surface of temporal and occipital lobes
* overlap onto lateral surface and supply thin border of the cortex |
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Which vessels in brain are particularly susceptible to high BP?
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- inferior choroidal aa.
- deep penetrating arteries of the MCA |
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What provides most blood supply to uncus?
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Anterior choroidal arteries ( typically off int. carotid but sometimes arise from MCA)
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What supplies internal capsule and basal ganglia?
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Lenticulostriate arteries ( medial off ACA or lateral off MCA)
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