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99 Cards in this Set
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- Back
- 3rd side (hint)
What does the frontal cortex control?
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initiation and control of voluntary movement, language expression; attention; emotion
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What does the parietal cortex control?
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perception and discrimination of somatosensory stimuli; integration of somatosensory stimuli with visual and auditory info
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What does the occipital cortex control?
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perception and recognition of visual stimuli
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What does the temporal cortex control?
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perception and discrimination of auditory stimuli; language perception; vision; learning and memory formation
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What does the insular cortex control?
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visceral sensations such as baro and GI receptors
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What does the internal capsule convey?
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UMN afferents and efferents from cortex down to lower levels and other regions of the cortex, lesions here cause wide ranging effects
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What does the corpus callosum convey?
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largest pathway in the brain which interconnects homotopic areas in contralateral hemisheres
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What does the anterior commissure of the corpus callosum connect?
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interconnects area of the middle and inferior temporal gyri: temporal lobes and olfactory bulbs
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What are association bundles of the cerebral cortex?
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intracortical fasciculi interconnecting different regions of the same hemisphere, arise from pyramidal neurons in layer II of the cortex
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What does the cingulum association bundle connect and where is it located?
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interconnects parietal and occipital lobes with the frontal lobe; located deep to the cingulate gyrus on the medial surface of the hemisphere
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What does the superior longitudinal fasciculus (arcuate fasciculus) association bundle connect and where is it located?
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interconnects temporal and frontal lobe language areas; damage in the dominant hemisphere results in conduction aphasia
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What are the six layers of the neocortex?
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Supragranular layers: I (molecular); II (external granular); III (external pyramidal)
Internal granular layer (IV) Infragranular layers: V (ganglionic or internal pyramidal layer); VI (fusiform layer) |
None
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What are the two basic cell types of the cerebral cortex?
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pyramidal cells - long axon projection neurons in layers II, III, V, VI; Stellate or granule cells - short axon "local circuit" neurons in layer IV
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What fibers are received in the internal granule layer (IV) of the cortex?
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thalamocortical fibers, especially from ventral tier thalamic nuclei and geniculate nuclei
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What fibers project from the ganglionic or internal pyramidal layer (V) of the cortex?
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corticostriate, corticospinal, corticopontine, corticobulbar, corticorubral fibers
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What fibers project from the fusiform layer (VI) of the cortex?
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corticothalamic fibers
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What fibers are formed from the supragranular layers (II, III) of the cortex?
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intracortical (associational) and intercortical (callosal) connections to other parts of the cortex within the ipsilateral or contrallateral cortex
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What are the characteristics of the pyramidal cells of the cerebral cortex?
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located within layers II, III, V, and VI; include giant Betz cells which give rise to some corticospinal tract; have an apical dendrite projecting toward cortical surface, basal dendrites project horizontally and an axon which extends into subcortical white matter
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What are the characteristics of the stellate or granule cells of the cerebral cortex?
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prominent in layer IV; have short axon that does not leave the cortex (intracortical)
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What Brodmann's areas are associated with motor control cortex?
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4, 6
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What Brodmann's areas are associated with somatosensory cortex?
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3,1, 2
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What Brodmann's areas are associated with visual input?
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17, 18, 19
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What Brodmann's areas are associated with auditory input?
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41, 42
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What are mirror neurons and there function?
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neurons of the frontal cortex which fire both when you move and when you observe another person make the same type of movement; also the the same neurons which fire when you smell something noxious or observe another smelling something noxious
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What are the "big six" functional areas of the cerebral cortex?
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S1, M1, V1, A1, Broca, Wernicke
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What are the characteristics of the primary somatosensory cortex (S1)?
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in postcentral gyrus (BA 3,1,2); has dense lamina IV, receives afferents from the VPL and VPM thalamic nuclei which come from medial lemniscal, spinothalamic, and trigeminothalamic tracts; somatotopy with lower limb hanging medially for each cortical area
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What are the symptoms of a lesion of the primary somatosensory cortex (S1)?
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contralateral deficits, inability to discriminate size, texture, and shape, loss of limb position sense, loss of pain localization
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What are the characteristics of the primary motor cortex (M1)?
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in precentral gyrus (BA 4, 6); large lamina V with giant Betz cells and very small lamina IV, receives afferents from ventral lateral thalamic nucleus relay from cerebellar afferents; efferents include corticospinal, corticobulbar, corticopontine, corticostriate, corticothalamic; is the location of UMNs; somatotopy
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What are the symptoms of a lesion of the primary motor cortex (M1)?
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spastic paralysis of the contralateral face, arm, and leg
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What are the characteristics of the primary visual cortex (V1)?
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located along the banks of calcarine sulcus (BA 17); prominent lamina IV; afferents from the lateral geniculate of thalamus with visual input from the contralateral visual hemifield of each eye; posterior 1/3 has afferents from the macular retina; efferents project to superior colliculus of tectum and generate visual tracking eye movements
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What are the symptoms of a lesion of the primary visual cortex (V1)?
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cortical blindness - inability to see anything consciously; loss of reflex closure of eyelids to bright light if bilateral lesion; unilateral lesions cause contralateral homonymous hemianopsia (contralateral visual field loss of each eye)
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What are the characteristics of the primary auditory cortex (A1, A2)?
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located in the superior temporal gyrus in transverse temporal gyri (BA 41, 42); large lamina IV; afferents from the medial geniculate nucleus of thalamus relaying bilateral auditory inputs; tonotopic localization with high frequencies medially and low frequencies laterally
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What are the symptoms of a lesion of the primary auditory cortex (A1, A2)?
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Area 41: unilateral lesion may not result in noticable hearing deficits bc compensation with other ear; Area 42: inability to recognize or discriminate sounds
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What are the characteristics of Broca's area and what symptoms does a lesion here produce?
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usually Left inferior frontal gyrus (BA 44,45); related to speech production; lesion causes expressive aphasia- in which the production of speech is impaired - telegraphic speech, able to comprehend just not express
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What are the characteristics of Wernicke's area and what symptoms does a lesion here produce?
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usually left superior temporal gyrus encircling the primary auditory cortex; invovled in language comprehension, lesion causes Wernicke's aphasia where understanding speech is lost leading to nonsense speech
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What are the characteristics of the secondary somatosensory cortex (S2)?
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caudal to S1 buried in upper bank of lateral fissure (BA 40); contains a separate, less detailed somatotopic map from S1, afferents from S1, VPL, VPM and posterior and intralaminar nuclei; responds to painful stimuli
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What are the symptoms of a VPL/VPM lesion?
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complete numbness on entire contralateral side of body with deficits in postion sense, and discrimination of texture, size, and shape (astereognosis)
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What are the characteristics of the posterior parietal cortex?
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located in superior parietal lobule (BA 5,7); afferents from primary and secondary somatosensory, visual, and auditory cortex; integrates various senses and involved in visual attention
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What are the symptoms of a lesion of the posterior parietal cortex?
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astereognosis - unable to recognize objects by touch though sensory pathways are intact; also neglect syndrome- denial/neglect of contralateral body
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What are the characteristics of the Premotor Cortex (PM)?
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anterior to primary motor cortex (BA 6); involved in preparation of movement; afferents from ventral anterior nucleus of thalamus relay from basal ganglia and corticocortical afferents from other motor and somatosensory cortices; efferents: corticospinal, corticobulbar, corticopontine, corticostriate, corticothalamic
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What are the characteristics of the Supplementary Motor Cortex (SMA)?
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BA 6, involved in coordinating posture and complex bilateral movements; afferents from basal ganglia
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What are the characteristics of the Frontal Eye Field (FEF)?
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in medial BA 6 rostral to premotor cortex, generates saccadic eye movements; stimulates eye and head movements to contralateral side; affferents from medial dorsal thalamic nucleus and dorsolateral prefrontal cortex; efferents to corticotectal tract and corticobulbar to PPRF
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What are the symptoms of a lesion to the dorsolateral prefrontal cortex lesion?
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normally can inhibit superior colliculus output of reflex eye and head movement towards stimuli (look away task); lesion leads to increaed antisaccade errors - inability to disregard or not look at a stimuli
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What is language?
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communication by means of symbols, including non-verbal
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What is phonation?
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forcing air past the closing vocal cords, function of CN X, larynx and respiratory system
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What is articulation?
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uttering, pronouncing distinct sounds, function of muscles of lips, tongue, palate, and pharynx (CN VII, IX, X, XII), cerebellum and extrapyramidal systems
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What is aphasia?
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disorder of previously acquired language ability caused by lesion in one or more critical cortical areas in the dominant hemisphere
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What artery supplies the cortical language areas?
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middle cerebral artery
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If an aphasic person is able to speak well but their communication is impaired, where is the lesion?
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Wernicke's of posterior superior temporal lobe
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If an aphasic person is unable to speak but is able to demonstrate normal comprehension, where is the lesion?
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Broca's of posterior inferior frontal lobe
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What is fluency?
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the ease, facility, and quantity of speech regardless of content or meaning
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Where is the lesion and what are the symptoms of a conduction aphasia?
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lesion of the arcuate fasciculus connecting Broca's and Weirnicke's areas; pt is fairly fluent, some paraphasic errors, some limited comprehension and repetition errors
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What is common among any/all Perisylvian aphasia (broca's, wernicke's, or conduction)?
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imperfect repetition
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What is done to test one's language ability?
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engage in spontaneous conversation; name items; repeat phrases; follow spoken and written commands; reading passages; writing to dictation
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What is paraphasia?
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word or syllable substitutions: phonemic; semantic; neologism (nonsense)
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What kind of aphasia commonly presents with paraphasic errors?
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Fluent aphasia, especially Wernicke's aphasia
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What are symptoms of Broca's aphasia?
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nonfluency, use of few words, comprehension is preserved, occasionally with right hemiparesis bc. Broca's is near the primary motor cortex
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What are the symptoms of Wernicke's aphasia?
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fluent speech with few meaningful words, poor comprehension
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What is prosody?
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the semantic and emotional meaning conveyed by different vocal pitch, inflection, melody, or tone of speech; loss of aprosodia is associated with lesions of the nondominant hemisphere
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What is necessary for the neural plate to form from the neuroectoderm?
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an underlying layer of mesoderm formed following the invagination of ectoderm cells during the primitive streak formation of the third week
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What three levels of organization is there within the neural plate?
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polarity, bilateral symmetry; regionalization
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What is the neural plate and how is it formed?
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elongated slipper-shaped plate of thickened neuroectoderm, appears at the beginning of the 3rd week of development that are formed due to the underlying mesoderm layer; the cells proliferate and form a stratified epithelium
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What is the neural groove?
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formed when the neural plate begins to fold inward due to the growth on the lateral margins of the neural plate extending
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What is the neural tube?
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formed following the fusion of the folds of the neural plate, forming a hollow tube around the 21-22 day embryo; proceeds rostrally and caudally
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What are the most common cause of perinatal death?
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neural tube defects
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Where do neural crest cells arise from and what do they form?
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the fusion point of the neural plates forming the neural tube; form the peripheral nervous system while the neuroepithelium forms the CNS; with one exception: peripheral motor neuron develops from the basal floor of the neural epithelim and the axon is sent into the periphery
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What is the origin of the peripheral motor neuron?
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basal floor of the neural epithelium, not the neural crest cells
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What are somites?
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38-40 pairs of mesodermal tissue blocks along axis formed beginning on the 17th day; differentiate into sclerotome (skeleton/cartilage); mytome (muscles); dermatome (dermis and subcut. Tissue); innervated by GSA, GSE
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What are the three initial vesicles of the CNS?
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prosencephalon; mesencephalon; rhombencephalon
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What does the prosencephalon develop into?
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Telencephalon (cerebral cortex, basal nuclei; lateral ventricle); diencephalon (thalamus, hypothalamus; 3rd ventricle)
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What does the mesencephalon develop into?
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mesencephalon (midbrain; cerebral aqueduct)
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What does the rhombencephalon develop into?
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metencephalon (pons, cerebellum; 4th ventricle); myelencephalon (medulla)
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What are the three layers of the developing CNS and what does each layer form?
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1. central ventricular zone (CNS neurons and glia); 2. mantle layer (gray matter); 3. marginal layer (white matter)
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What is the origin of microglial cells?
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mesenchymal cell; CNS macrophage derived from mesoderm derived monocytes and integrate into CNS
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What four cell types do the neuroepithelial cells differentiate in to?
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neuroblasts (immature neuron); Oligodendrocytes (glia); astrocytes (glia); ependymal (line the ventricles)
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What is spina bifida occulta?
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least severe and most common type of spina bifida; defect in the vertebral arch fusion in sacrolumbar region
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What is spina bifida cystica?
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protrusion of the spinal cord/meninges along with defect in verebral arch fusion: meningocele; meningomyelocele; or myeloschisis
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What is spina bifida cystica with meningocele?
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vertebral arch fusion defect in which the meninges project through the vertebral defect forming a sac filled with CSF
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What is spina bifida cystica with meningomyelocele?
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vertebral arch fusion defect in which the meninges and spinal cord project through the vertebral defect forming a sac
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What is spina bifida cystica with myeloschisis?
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vertebral arch fusion defect in which an open neural tube lies on the surface of the back
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What is rachischisis?
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many defective vertebrae formations
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What is anencephaly?
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failure of the anterior neuropore to close and failure of the brain to develop
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What are symptoms of posterior fossa lesion?
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HA, nausea, visual disturbance, facial pain, dizziness, hearing loss, dysphagia, ataxia, tremor
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What structures pass through the foramen magnum?
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spinal cord; spinal accessory nerve; vertebral arteries; venous plexus of verebral canal; anterior and posterior spinal arteries
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What are the superior and inferior borders of the posterior fossa?
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superior: tentorium cerebelli; inferior: occipital sinus; sigmoid, transverse sinus
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What is the dual role of medicine?
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prolong life where feasible and appropriate; provide comfort, relieve suffering in untreatable/hopeless conditions
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What is the pathophysiological cause of multiple sclerosis (MS)?
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immune mediated destruction of normal CNS myelin (demyelinating, not dysmyelinating where the myelin is never formed); white matter plaques slowing axonal conduction
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What are some possible etiologies of MS?
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environmental (temperate latitudes; viral exposure); autoimmune (Igs directed at CNS myelin enters CNS possible similar structure to virus); hereditary (risk of MS 20x greater in 1st degree relative)
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What are the clinical manifestations of MS?
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onset in young adulthood (20-40); females to males (2:1); sensory or motor deficits in lower limbs, optic neuritis (blurred optic disc margin); episodic (relapsing-remitting 80%)
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What are typical features of MS?
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Lhermitte's sign (electric shock sensation down spine into legs or arms); trigeminal neuralgia; internuclear opthalmoplegia (MLF)
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What are some ancillary test for MS?
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MRI; VEP (see if normal cortical response time); CSF analysis (high IgG, oligoclonal bands; high lymphocytes)
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What are the treatments for MS?
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no curative: corticosteroids for acute symptoms; interferon Beta, Copolymer taken chronically to lessen cumulative severity of disability; symptomatic treatments
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What are the functions of astrocytes?
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endfeet surround blood vessels and synapses forming BBB; prevent NT (esp. GABA and glutamate) from diffusing away from synapse and recycle glutamine; regulate ions esp. K+; detox CNS; scaffolding for migration of neurons, source of adhesion molecules if damaged forms glial scar
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What are the functions of oligodendrocytes?
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myelinating cells of CNS, myelinates up to 40-50 nearby axon segments, including optic n. (which is really a tract)
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What are the functions of microglia?
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macrophages to phagocytize and produce cytokines: IL-1, prostaglandins, and leukotrienes
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What is the function of schwann cells?
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neural crest derived glial cells which myelinate one axon segment of a peripheral neuron, provide a growth permissive environment for axon, PMP-22 protein necessary for proper myelin formation over/under expression can lead to peripheral neuropathies
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What are the functions of microtubules and microfilaments within neurons?
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both carry out axonal transport, bidirectional flow of molecules (slow anterograde for growth and fast antero/retrograde for transport); microtubles function in the growth of the axon in length; microfilaments responsible for radial growth of axon
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What are the different types of synapses?
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axo-dendritic; axo-somatic; axo-axonal; neuromuscular; excitatory/inhibitory; symmetrical/asymmetrical
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What are neural stem cells?
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progenitor cells that give rise to more differentiated cells but remain in cell cycle: blastocyst is source of true stem cell from embryo or neuroblast; adult from subventricular zone or hematopoietic stem cells
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