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99 Cards in this Set
- Front
- Back
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Cerebrum
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2 hemispheres that cover diencephalon and brainstem, 83% of brain mass
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Longitudinal fissure
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separates hemispheres
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Transverse cerebral fissure
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separates cerebrum and cerebellum
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Sulci
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shallow grooves of surface of cerebrum, deeper ones divide cerebrum into 5 major lobes (frontal, parietal, occipetal, temporal, insula)
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Central sulcus
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separates frontal and parietal lobes, bordered by precentral gyrus and postcentral gyrus
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Parieto-occipital sulcus
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separates occipital and parietal lobe
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Lateral sulcus
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separates temporal lobe from parietal and frontal lobes
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Insula lobe
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positioned deep within lateral sulcus, forms part of floor
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Gyri
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ridges of brain tissue b/w sulci
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Cerebral cortex
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folds in cortex triples surface area, 40% brain mass, no fiber tracts, function = awareness, sensations, voluntary movements, communation, memory, understanding, certain functional regions
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Primary sensory cortex
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sensory area for each major sense, awareness of sensation
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Sensory association areas
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processes sensory info, give meaning
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Multimodal association areas
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integrate info to enable purposeful actions, develop motor response (posterior, anterior, limbic), make associations b/w different kinds of sensory info
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Posterior association area
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at interface of visual, auditory, and somatosensory association areas, integrates info from those 3, proprioceptive senses and vestibular apparatus = allows awareness of spatial location of body, guides movement of limbs through space, language comprehension and speech (mostly left cortex but also corresponding areas in right [creative interpretation of word, emotional overtones], Wernicke’s area, temporal lobe [coordination of aud/vis aspects of language], parts of insula [initiation of word articulation/recognition of sound sequences])
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Anterior association area
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prefrontal cortex, integrates info from all association areas to plan/initiate motor responses, receives association info and adjusts motor outpur accordingly, uses past experience (connection to limbic ass. area), working memory for spatial tasks, object-recall tasks, complex multi-task problems, executive area for task management, 3 working memory areas (visual, auditory, executive manages both), cognitive functioning, abstract, reasoning, long-term planning, impulse control, mental flexibility, social skills, humor/empathy/conscience, mood, last part of brain to mature (early adulthood)
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Limbic association area
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medial side of frontal lobe, processes emotions in complex personal/social interactions, integrates input from other cortical areas to form memory, uses past to influence future
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primary motor cortex
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voluntary motor movements, precentral gyrus of frontal lobe, has pyramidal cells, long axons of pyramidal cells form massive pyramidal tracts that descend through brainstem/spinal cord, axons synapse on motor neurons to generate precise movements, contralateral projection
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premotor cortex
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complex motor movements involving sensory feedback and planning movements, located anterior to precentral gyrus
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frontal eye field
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controls voluntary movements of eye, anterior to premotor cortex
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broca’s area
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controls speech production, anterior to inferior part of pre-motor cortex in left hemisphere, connected to language comprehension areas, corresponding area on the right (controls emotional overtones in words)
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commissures of white matter
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connect the corresponding cortices of hemispheres
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association fibers of white matter
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connect different parts of cortex in same hemisphere
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projection fibers of white matter
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connect cortex to more caudal parts of CNS
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basal ganglia of gray matter
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control movements with motor cortex (corpus striatum, globus pallidus)
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basal forebrain nuclei of gray matter
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arousal, learning memory, motor control (septum, horizontal bands of broca, basal nuclei of Meynert)
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claustrum of gray matter
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may integrate info from cerebral cortex and limbic system
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primary somatosensory cortex
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along postcentral gyrus of parietal lobe, involved with conscious awareness of general somatic senses (touch, pressure, vibration, pain, temp), projection in contralateral from sensory receptors to sensory cortex, hemispheres receive sensory input from opposite side of body
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spatial discrimination
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ability to precisely locate a stimulus
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somatotopy
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each region of cortex receives sensory stimuli from specific area of body
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sensory homunculus
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body map of sensory cortex in postcentral gyrus
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motor homunculus
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body map of primary motor cortex
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somatosensory association cortex
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posterior to primary somatosensory cortex, integrates different sensory inputs to understand sensations, draws upon stored memories of past sensory experiences
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primary visual cortex
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deep in calcarine sulcus, damage can cause blindness, largest of all sensory areas, visual info originates from retina, contralateral function
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visual association area
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surrounds primary visual area, covers occipital lobe, continues processing visual info, 30 cortical areas for visual processing, info proceeds in 2 streams (ventral and dorsal)
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ventral stream
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“what” pathway, passes info into inferior part of temporal lobe, recognizing objects/words/faces
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dorsal stream
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“where” pathway, extends through posterior parietal cortex to post-central gyrus, perceives info about spatial relationships among objects
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primary auditory cortex
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sound waves excite receptors in inner ear cochlea which triggers impulse transmission, conscious awareness of sound is detected, at superior edge of temporal lobe
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auditory association are
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posterior/lateral to primary auditory cortex, evaluation of sounds and integrates memories of past sounds, auditory stimuli processed serially in parallel along 2 pathways (posterolateral and anterolateral)
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posterolateral pathway
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“where” pathway, through parietal lobe to lateral prefrontal cortex, evaluates location of stimulus
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anterolateral pathway
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“what” pathway, from anterior temporal lobe to inferior pre-frontal cortex processes info related to sound ID
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Wernicke’s area
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in one hemisphere, where audotory association area overlaps with Wernicke’s area, functional brain region involved in recognizing/understanding spoken words, damage interferes with ability to comprehend speech
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Vestibular cortex
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processes info from vestibular apparatus, responsible for conscious awareness of sense of balance (position of head in space), located in posterior part of insula lobe deep to lateral sulcus
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Gustatory cortex
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processes taste stimuli from tongue, involved in conscious awareness of taste stimuli, located in insula on roof lateral sulcus
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Olfactory cortex
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smell, olfactory nerves from nasal cavity transmit impulses to olfactory cortex, provides conscious awareness of smells, on medial aspect of cerebrumin piriform lobe
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Rhinencephalon
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“nose brain”, includes piriform lobe, olfactory tracts/bulbs, connects to limbic system (explains why smells trigger emotions), involved with consciously IDing/recalling specific smells
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Visceral sensory areas
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deep in lateral sulcus in insula lobe, receives general sensory input (pain, pressure, hunger) from abdmonial/thoracic organs
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Left hemisphere
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language abilities, math, logic
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Right hemisphere
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visual-spatial skills, reading facial expressions, intuition, emotion, artistic, music
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Cerebral white matter
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allows different areas of cerebral cortex to communicate with each other and with brainstem and spinal cord, usually myelinated and bundled into tracts
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Commissural fibers of white matter
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connect cortices in hemispheres, horizontal fibers interconnect gray areas of right/left cerebral hemispheres
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Corpus callosum
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largest commissure, broad band laying superior to lateral ventricles
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Association fibers
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connect cerebral cortex of different part of same hemisphere, short and long association fibers, parts of Wernicke’s and broca’s areas connected by these fibers
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Projection fibers
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connect cerebral cortex to caudal parts of CNS or ascend to cortex from lower regions, how sensory information reaches cerebral cortex and motor instructions leave
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Internal capsule
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bundle of projection fibers that pass b/w thalamus and deep gray matter
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Corona radiata
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formed by fan of projection fibers running to/from cerebral cortex
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Deep gray matter of cerebrum
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basal ganglia, basal forebrain nuclei, claustrum, amygdala
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Basal ganglia
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group of nuclei embedded deep in white matter, caudate nucleus = arches superiorly over thalamus, lies medial to internal capsule, globus pallidus = lateral to internal capsule, putamen = lateral to internal capsule, striatum = combo of caudate nucleus and putamen, corpus striatum = combo of caudate nucleus, putamen, and globus pallidus, receives input from many areas, complex neural calculators in control/regulation of many movement types and intensities, select appropriate muscles for task, estimate passage of time, also influenced by substantia nigria in midbrain (degeneration cancels inhibitory input to basal ganglia, results in overactive globus pallidus which inhibits motor cortex causing slow/jerky movements [parkinson’s disease])
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Dyskinesia
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degeneration of basal ganglia which causes abnormal motor function
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Huntington’s disease
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degeneration of corpus striatum pathway that inhibits motor activity, overstimulation of motor activities with uncontrolled jerking and early death
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Basal forebrain nuclei
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cholinergic system (release acetylcholine), location = anterior/dorsal to hypothalamus, function = arousal, learning, memory, motor control, septum, diagonal band of Broca, horizontal band of Broca, basal nucleus of Meynert
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Alzheimer’s disease
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degeneration of basal forebrain nuclei, results in reduction of cholinergic activity, form of dementia
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Limbic system
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medial aspect of cerebral hemispheres (also within diencephalon, anterior thalamic nuclei, hypothalamus, mammillary body), forms broad ring (septal nuclei, cingulated gyrus, dentate gyrus, hippocampal formation, part of amygdala), fornix and anterior commissure fiber tracts link limbic system together, also overlaps with rhinencephalon
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Cingulate gyrus
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superior to corpus mallosum, shifting b/w thoughts and express emotions through gestures, interprets pain as unpleasant, resolves mental conflict during frustration
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Amygdala
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subcortical gray matter that contains the key brain nuclei for processing fear and triggering the appropriate sympathetic response, recognizing menacing facial expressions and detect precise gaze of someone looking at them, forms memories of past experiences based on emotional impact, retrieves memories and re-experiences them (protective to remind people of dangers)
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PTSD
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extreme response to triggered memory can result in hyperactivity in amygdala and dysfunction in medial pre-frontal cortex and hippocampus
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Hippocampal formation
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hippocampus + parahippocampal gyrus, encodes, consolidates, and later retrieves memories of facts and events, receives info to be remembered from the rest of cortex, then processes data and returns them to cortex where they are stored as long term memories
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Limbic system and the brain
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most output relayed through hypothalamus and reticular formation which control visceral responses, also interacts with prefrontal cortex of cerebrum (feelings from emotional brain interact with thoughts from thinking brain)
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Reticular formation
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runs through central core of medulla, pons, and midbrain, forms 3 columns (midline raphe nuclei, medial nuclear group, lateral nuclear group), axons project to widely separated regions, ideal for brain arousal as a whole, certain reticular neurons send continuous stream of impulses to cerebrum through relays in thalamus, maintaining cerebral cortex in alert
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Reticular activating system (RAS)
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maintains consciousness and alertness, axons from all sensory tracts synapse on RAS neurons, stimuli help keep people awake/alert, functions in sleep/arousal from sleep, anesthesia drugs depress RAS, malfunctions causes narcolepsy, severe injury causes coma
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RAS motor arm
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sends axons to spinal cord, which control motor neurons to skeletal muscle, some axons and lateral nuclear group nuclei influence autonomic neurons which regulate visceral motor functions
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Dura sinuses of meninges
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2 layers of dura mater fused except where they separate to enclose blood-filled dural sinuses = collect blood from brain and conduct it to large internal jugular veins, superior sagittal sinus is largest, positioned in superior midline
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Falx cerebri of dura mater
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large sickle shaped vertical sheet in median plane in longitudinal fissure b/w cerebral hemispheres, attaches to crista galli of ethmoid bone
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Falx cerebelli of dura mater
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vertical partition extends inferiorly from posterior part of falx cerebri, runs along vermis of cerebellum in cranial fossa
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Tentorium cerebelli of dura mater
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almost horizontal sheet lies in transverse fissure b/w cerebrum and cerebellum
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Arachnoid villi
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knoblike projections from arachnoid mater, project through dura mater over superior part of brain into sinuses, act as valves that allow CSF to pass from subarachnoid space into dural blood sinuses
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Choroid plexuses
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where CSF is formed, in all 4 ventricles, knot of porous capillaries surrounded by single layer of ependymal cells joined by tight junctions and bearing cilia, CSF continually forms from blood plasma by filtration from capillaries and passage through ependymal cells into ventricles
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CSF components
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glucose, oxygen, vitamins, ions (Na, Cl, Mg)
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CSF movement
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enters ventricles, enters subarachnoid space through lateral/median apertures in 4th ventricle walls, some enters central canal of spinal coird, flows through and baths outer surfaces of brain/spinal cord, passes through arachnoid villi and absorbed into blood through venous dural sinuses
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CSF cycling
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arises from blood and returns to it at a rate of 500 ml/day
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Hydrocephalus
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excessive accumulation of CSF in ventricles and/or subarachnoid space
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BBB
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rich supply of capillaries provides nutrients to brain, tight junctions join endothelial cells in brain capillaries make them least permeable capillaries in body, prevents blood-borne toxins from entering brain, not absolute
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CNS pathways
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in white matter, connect brain and body periphery, composed of interconnected fiber tracts that relay info from one part of CNS to another part, ascending and descending pathways, most pass from one side of CNS to other at some point, chain of 2-3 neurons, most pathways exhibit somatotopy with axons in tracts spatially arranged in specific way, all pathways paired with tracts on right/left sides
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Ascending pathways
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spinocerebellar, dorsal column, spinothalamic pathways
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Spinocerebellar pathway
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1st order neuron: sensory receptor to dorsal gray horn of spinal cord, 2nd: up spinal cord in dorsal/ventral spinocerebellar tracts to cerebellum, terminates, ipsilateral, info on proprioception from lower limbs/trunk to cerebellum to coordinate body movements
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Dorsal column pathway
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1st order neuron: sensory receptor to spinal cord, ascends up 2 dorsal white column tracts (fasciculus gracilis/cuneatus) to brain nuclei in medulla and synapses, 2nd: decussates in medulla, up medial lemniscus tract in thalamus synapses, 3rd: thalamus to primary somatosensory cortex where it is processed, contralateral, discriminative senses, fine touch/pressure, conscious aspects of proprioception
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Spinothalamic pathway
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1st order neuron: sensory neuron from sensory receptor to spinal cord, synapses in dorsal gray horn, 2nd: decussate in spinal cord, enter funiculi, ascends up spinal cord to thalamus, 3rd: thalamus to primary somatosensory cortex, processed into conscious sensations typically unpleasant (pain, temp, deep pressure), non-discriminative touch, contralateral
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Descending pathways
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most motor pathways, decussate at some point along course, contralateral, a chain of 2-3 neurons, somatotopy (tracts arranged according to body region supplied), paired pathways, deliver motor instructions from brain to spinal cord, pyramidal tracts and others (tectospinal, westibulospinal, rubrospinal, reticulospinal → subconscious movements)
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Pyramidal pathway
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form primary motor cortex through internal capsule to spinal gray matter, lateral tracts decussate in medulla, ventral in spinal cord, axons either synapse with short interneurons that activate somatic motor neurons OR synapse directly onto somatic motor neurons (goes directly to peripheral motor receptor), control precise/skilled voluntary movements, limb muscles
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Lou gehrig’s disease, amyotropic lateral sclerosis
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degeneration of pyramidal tracts with formation of hardened scar tissue in lateral parts of spinal cord, wasting and atrophy of skeletal muscles, fatal
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Rubrospinal tract
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from red nucleus in midbrain, decussates in midbrain and descends to spinal gray matter, axons either synapse with short interneurons that activate somatic motor neurons OR synapse directly with somatic motor neurons
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Tectospinal tract
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from superior colliculus in midbrain
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Reticulospinal tract
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from reticular formation, median nuclear groups of pons and medulla
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Vestibulospinal tract
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from vestibular nuclei in medulla
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Integration of movement
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cerebellum smoothes/coordinates movements dictated by pyramidal tracts and subcortical motor nuclei, axons from cerebellum project to and influence red nuclei, vestibular nuclei, and reticular nuclei, pyramidal tract neurons influence most of “other” tracts
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Paralysis
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loss of motor function
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Parasthesia
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loss of sensation
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Paraplegia
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injury to spinal cord b/w T1 and L2 causing paralysis of lower limbs
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Quadriplegia
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injury to spinal cord in cervical region causing paralysis of all four limbs
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Cerebrovascular accident (stroke)
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inturruption of blood flow to brain tissue, thrombotic = caused by clot, hemorrhagic = caused by bleed to brain which impairs blood flow
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