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75 Cards in this Set
- Front
- Back
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Motor System
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*Corticobulbar--> brainstem
--> innervates cranial nerves *Corticospinal-->medulla -->innervates spinal nerves |
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Sensory System
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DCML-->caudal medulla
-->epicritic sensation:fine discriminative touch -->fasciculus gracilis: low 1/2 of body -->fasciculus cuneatus: upper 1/2 of body AL--> spinal column -->protopathic system-->pain, temp, crude touch *lateral spinothalamic tract-pain+temp *anterior spinothalamic tract-general tract |
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Contralateral hemiplegia, contralateral hemianesthesia (of face,trunk, and upper extremity) and cortical sensory loss (failure to identify an object through touch or to ID a letter or word written on the surface of the skin) suggests a ?
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Cortical lesion
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The cerebral cortex contains ?
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Language cortex (aphasia)
Sensory cortex (anesthesia and cortical sensory loss) motor cortex (paralysis) |
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Left cortical lesion involving the motor fibers above the level of their crossing results in?
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Right sided paralysis
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A lesion in the left brain affects the sensory fibers originating from the right half of the body and results in ?
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Sensory loss (anesthesia) in the right side of the body
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The left cerebral cortex contains sites for ?
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Language (aphasia)
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The right (nondominant) hemisphere regulates ?
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visuospatial orientation, emotional and prosodic function, attention, and sensorimotor control for the left half of the body
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Contralateral hemiplegia and loss of pain and temperature equally for the face, arms, and legs are associated with a ?
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subcortical (internal capsule) lesion
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Involuntary movements suggests a ?
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basal ganglia lesion
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Bilateral loss of pain and temperature sensation with preserved sense of touch in the same limbs (usually the two upper limbs) implies a lesion in the ?
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spinal central gray
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This lesion interrupts the decussating fibers of the anterior white commissure, which mediates?
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pain and temperature sensation
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Blindness in one eye suggests an ?
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optic nerve lesion anterior to the optic chiasm
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Bitemporal hemianopia (one does not see things laterally in the visual fields) results from a lesion ?
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compressing or interrupting crossing fibers (from the nasal retina of each eye) in the optic chiasm
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Homonymous hemianopia is associated with a lesion of the ?
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optic tract anywhere between the optic chiasm and the occipital lobe
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Visual agnosia, alexia (failure to comprehend written material) homonymous hemianopia and spared macular vision are all associated with a lesion of the ?
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visual cortex (Brodmann area 17) and visual association areas (Brodmann areas 18 and 19)
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What is the difference between the retinal field (RF) and the visual field (VF)?
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RF- the focused representation of the visual field. The retinal image is the reverse of the visual field image--up becomes down and left becomes right
VF-the external area visible to one or both eyes without movement. Area in outside world that you see |
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How does the VF get projected onto the retina and onto the visual cortex?
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Vision is generated by photoreceptors in the retina, a layer of cells at the back of the eye. The information leaves the eye by way of the optic nerve, and there is a partial crossing of axons at the optic chiasm. After the chiasm, the axons are called the optic tract. The optic tract wraps around the midbrain to get to the lateral geniculate nucleus (LGN), where all the axons must synapse. From there, the LGN axons fan out through the deep white matter of the brain as the optic radiations, which will ultimately travel to primary visual cortex, at the back of the brain.
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Where is the visual cortex?
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Occipital Lobe
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Describe how the nasal and temporal halfs are projected on to the retina and on to the visual cortex?
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-Nasal (RF) temporal (VF)
-Optic fibers temporal to fovea with respect to RF connect with cerebral cortex-->ipsilaterally -optic fibers nasal to fovea with respect to RF cross over at optic chasm to-->contralateral cerebral cortex -Temporal half of VF projects on: nasal half of retinal field (RF) -Nasal half of VF projects on: temporal half of retinal field (RF) -Top object (VF)-->lower retina -bottom object (VF)--> upper retina |
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Fovea
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-center of retina
-most acute vision -projects to tip of occipital lobe |
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Describe how the superior and inferior quadrants are projected on to the retina and on to the visual cortex?
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-Upper (superior) vs lower (inferior)
-Superior VF projects below: calcarine fissure in occipital lobe -Inferior VF projects above: calcarine fissure in occipital lobe -In occipital lobe everything is: upside down and backwards with respect to VFs |
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What type of visual deficits result from color vision problems?
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Color Vision Problems:
*Protanopic: lacks red cones sees green and blue *Deuteranopic: lacks green cones sees red and blue *Tritanopic:lacks blue cones sees red and green *Etiology: acquired or genetic factors |
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Visual deficits
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Homonymous- similar regions of the VF defects per eye
R-half vs. L-half of the VFs for both eyes Heteronymous-deferent regions of VF defects for each eye -R-half of VF for one eye versus L-half of VF for one eye |
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Bitemporal Heteronymous Hemianopsia
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-Loss of vision in temporal visual fields
-Pathology: optic chasm -Tumor: pituitary gland -Interrupts fibers from both nasal retinas -Produces blindness in temporal VFs |
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Nasal Hemianopsia
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-Loss of vision in the nasal field of one eye
-Pathology: lateral edge of optic chiasm -Interrupts fibers ipsilateral temporal portion of retina -Result: nasal hemianopsia |
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Homonymous Hemianopsia
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-Loss of vision in either R vs. L fields of both eyes
-Interruption of fibers-->any point along: *optic tract *geniculate body *geniculocalcarine fissure -Homonymous (same field) in both eyes |
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R-optic tract lesion
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-Interrupts visual fibers from retinas of both eyes
-L-VF defect for both R and L eyes |
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Upper L-Quadrantopsia
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-Loss of vision in L-upper quadrants of VFs for both eyes
-affecting R-lower quadrants of RFs -Pathology: temporal lobe pathology interrupting outer (ventral) fibers of geniculocalcarine tracts -Blindness of upper quadrants of VFs for both eyes |
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Lower L-Quadrantopsia
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-Loss of vision in L-lower quadrants of VFs for both eyes
-Interruption of info via R-upper RF or quadrants -Pathology: temporoparietal lobe pathology interrupting inner (dorsal) fibers of geniculocalcarine tracts |
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What specific thalamic nuclei serve as major gateways for transmission of sensory, auditory and visual information? Where do these nuclei project in the cortex?
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Ventral Posterior Nucleus (Lateral)- medial lemniscus and spinothalamic tracts. Primary sensory cortex. Relays somatosensory (protopathic, epicritic) sensation from neck, trunk, and extremities
Ventral Posterior nucleus (Medial)- Trigeminothalamic tracts. Lower third of the primary sensory cortex. Relays somatosensory (protopathic, epicritic) sensation from face Lateral geniculate body-optic tract. Primary visual cortex. Relays visual information. Medial geniculate body-inferior colliculus and lateral leminiscus. Relays auditory information. |
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Inferior Colliculus
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Found in the midbrain. One of the upper two rounded elevations. Mediates the transmission of auditory impulses from the ear to the thalamus and auditory cortex. Mediates reflexes triggered by auditory stimuli.
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Lateral leminiscus
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Found in the pons-midbrain. Relay information from both ears to the primary auditory cortex in the temporal lobe.
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medial leminscus
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Sensory pathways located in the dorsal third of the spinal cord and mediate epicritic proprioception, discriminative touch, two-point discrimination, pressure, and vibration sensation
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superior colliculus
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Midbrain structure related to visual reflexes, such as ocular accommodation and coordinated head and eye movements
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Pineal gland
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Found in the midbrain-diencephalon junction. Thalamic organ important in diurnal rhythm.
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Cerebral aqua duct
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Small tube shaped midbrain canal that connects the 3rd and 4th ventricles.
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medial geniculate nucleus
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Found in midbrain-diencephalon junction. Thalamic nucleus, transmits auditory information to the primary auditory cortex
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lateral geniculate nucleus
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Found in midbrain-diencephalon junction. Thalamic relay center for vision.
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VPL thalamic nucleus
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Ventral Posterior Lateral Nucleus. Found in the thalamus. Is the sensory relay nucleus that relays information related to somatic sensation from the body.
*It receives sensations of pain, temperature, and discriminative touch from the body via the ventral and lateral spinothalamic tracts and the medial lemiscus. *The efferent fibers mediate teh sensory information to the dorsal 2/3rds of the primary somesthetic cortex in the postcentral gyrus. |
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Fourth Ventricle
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It is located within the pons or in the upper part of the medulla. CSF entering the fourth ventricle through the cerebral aqueduct can exit to the subarachnoid space of the spinal cord through two lateral foramina of Luschka and a single, midline foramen of Magendie
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Cerebellum
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The cerebellum is located in the inferior posterior portion of the head (the hindbrain), directly dorsal to the pons, and inferior to the occipital lobe. The cerebellum is involved in the coordination of voluntary motor movement, balance and equilibrium and muscle tone.
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Inferior cerebellar peduncle (restiform body)
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Found in the cerebellum. The cerebellum is connected to the brainstem by this and the middle and superior peduncles.
Fibers transmit proprioceptive afferent information from the trunk and limbs and the vestibular information to the cerebellum. |
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What comprises the pyramidal system and where does it travel from cortex to brainstem?
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A major pathway of the central nervous system, originating in the sensorimotor areas of the cerebral cortex and generally descending through the brain stem to the spinal cord. The fibers of the pyramidal tract transmit motor impulses that function in the control of voluntary movement.
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Describe the direct activation pathway. Where does the DAP or pyramidal system end up and decussate?
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-The pyramidal tract (UMN-->precentral gyrus)
-Corticobulbar-->brainstem *innervates cranial nerves -Corticospinal (cross over-->medulla) *innervates-->spinal nerves *lateral corticospinal (90%) xover *anterior corticospinal (10%) don't xover |
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What role does the cerebellum play with respect to afferent and efferent innervation? If a lesion is in the cerebellum, what type of symptoms result?
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Coordination and control of voluntary movement.
Afferent: originate from the spinal cord, brainstem, and motor cortex. The inferior cerebellar peduncle is an important afferent pathway through which ascending inputs from the distal limbs gain a rapid entry to the ipsilateral cerebellum. The fiber bundles wthat enter through the inferior cerebellar peduncle are teh vestibulocerebellar, dorsal spinocerebellar, reticulocerebellar, olivocerebellar, and cuneocerebellar tracts. Efferent: the cerebellar efferents arise from three deep cerebellar nuclei: the dentate, emboliform, and globose and through the superior cerebellar peduncle.The fibers of the superior cerebellar peduncle descussate at the level of the inferior colliculus. Symptoms: Tremors, Nystagmus (Involuntary movement of the eye). Ataxia, lack of coordination. |
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What muscles innervate or move the eye? What cranial nerves innervate the muscles of the eye? What muscles does the left hemisphere innervate to the eye and vice versa. If therei sa lesion in the left hemisphere versus the right, what kind of symptoms will be produced?
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L-Hemi innervates:
*R-lateral rectus muscle (R-Cr.6) and L-medial rectus muscle (L-Cr. 3) -This produces a conjugate gaze to the left side *R-Hemi innervates: -L-lateral rectus muscle (L-Cr. 6) and R-medial rectus muscle (R-cr. 3) -This produces a conjugate gaze to the right side |
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There are a set of reflexes one can elicit to assess the integrity of the visual system. What are names of these reflexes called and what does it mean if the visual system does not respond to these reflexes? Where is the probably location of the lesion?
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Consensual reflex:
-pupillary constriction to light -shine light in one eye, constriction of both pupils -tests direct neuronal pathway from eye to midbrain -by passes lateral geniculate nucleus Accommodation Reflex: -tests neural network from visual cortex back to eye (focus lens of eye, and parasympathetic involvement) -lens focuses and pupil constricts -superior colliculus lesions |
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Describe the basic cochlear structure.
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The cochlea consists of three fluid-filledcavities: the scala vestibuli, scala media, and scala tympani.
Scala vestibuli: uppermost compartment, which follows the inner contour of the cochlear duct and joins the scala tympani at the apex of the cochlea though the helicotrema, a small aperture. The scala tymapni lies at the bottom and follows the outer contour of the cochlea. The scala media which ends near the cochlear apex, is between the scala tympani and scala vestibuli. The scalae vestibuli and tympani are filled with perilymph, a fluid with a high sodium concentration. The scala media, a membranous labyrinth, is filled with endolymph, a fluid with a high concentration of potassium. The scala media (cochlear duct) contains a sensory structure called the organ of Corti, which contains hair cells, the primary receptor cells. |
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Where are high and low frequency sounds localized within the cochlear mechanism and CNS and Heschl's gyrus?
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Low Fo-terminate in superficial layers/cochlear nucleus
High Fo-terminate in deep layers/cochlar nucleus Axons from the higher frequency organ of corti hair cells project to the dorsal portion of the anteroventral cochlear nucleus and the uppermost dorsal portions of the dorsal cochlear nucleus lower frequency axons from the organ of corti hair cells innervate the ventral portions of the dorsal cochlear nucleus and the ventrolatearl portions of the anteroventral cochlear nucleus |
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Describe the basic cochlear function
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Concerned with transferring sound vibrations into nerural impulses. It absorbs the mechanical energy produced by the movements of the stapes and transduces this energy into hydraulic energy, which passes through the perilymph in the scala vestibuli and the scala tympani.
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Describe the central auditory pathways including specific ganglia, nuclei, and neuronal projections
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-Involves a multisynaptic 1st, 2nd, 3rd order neuronal mechanisms
1st order: spiral ganglia *pass through internal auditory meatus 2nd order: cochlear nuclei *pontomedullary junction 3rd order: thalamus (medial geniculate nucleus) Extends: cochlear nucleus-->primary auditory cortex |
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Where is the primary association cortex and auditory association cortex?
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-Superior temporal gyrus
-surrounded by temporal planum hidden by temporal, parietal, frontal lobes -receives crossed and uncrossed fibers from both ears -High Fo fibers (from base) terminate-->posteromedial Heschl's gyrus -low Fo fibers (from apex) terminate-->anterolateral Heschl's gyrus |
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Describe ipsilateral and contralateral projections
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Cross midline in 3 pathways:
-dorsal acoustic stria -intermediate acoustic stria (IAS) -trapexoid body (form nucleus of Trapezoid) -So, there are contralateral and ipsilateral projections to auditory cortex -However, most are contralateral projections to cortex |
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What is meant by bilateral auditory representation?
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Bilateral Auditory Representation: Primary auditory cortex, receives inputs from both ears, multiple interconnections via ascending pathways:
-cochlear nuclei -lateral lemniscus -inferior colliculus |
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Major inputs to primary auditory cortex are from...
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Contralateral (opposite) ear
Fewer projections from ipsilateral ear |
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Central Auditory Pathway
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Lesion at any point along the central auditory pathway extending form medulla to auditory cortex
does not produce complete deafness in contralateral ear only causes mild loss of hearing at most in contralateral ear |
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Sound Source Localization
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Begins at the level of the superior olivary nucleus in the brainstem. It is the first nucleus to receive crossed and uncrossed projections from both ears, and it uses the time delay and intensity difference to determine the exact location and direction of sound sources
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Tonotopic Representation
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Tonal representation at the cochlear level is maintained throughout the central auditory pathway. Despite the multiple interconnections and crossings in the ascending pathways, the tonal representation from the hair cells in the cochlea is retained throughout the auditory system.
Tones are even represented in the primary auditory cortex, where a single neuron responds best to certain sound frequencies. |
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What is a sensorineural hearing impairment?
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Damage to the inner ear/cochlear
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What is the retrocochlear auditory mechanism?
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Transmits auditory signals from the hair cells in the organ of Corti to the brainstem chochlear nuclei. The hair cells transmit nerve impulses to the peripheral (unmyelinated) axons of the unipolar spiral ganglia (first-order neuron)
The central (myelinated) processes of th spiral ganglion cells form the acoustic branch of vestibulocochlear (CN VIII) nerve and pass through the internal auditory meatus, a canal in the petrous portion of t he temporal bone that opens into the cranial cavity at the side of the junction of the pons and medulla. |
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What components comprise the epicritic system and protopathic system?
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Sensory (DCML and AL)
DCML-epicritic sensation: fine discriminative touch Stereognosis: Id of objects by tactual sensation of shape, texture, and size Graphesthesia: ability used to recognize the outline of letters and symbols written on skin surface Kinesthesia: internal awareness of limb movement Proprioception: internal awareness of limb position in space Fasciculus gracilis: low 1/2 of body Fasciculus cuneatus: upper 1/2 of body AL-protopathic system: pain,temp, crude touch Lateral spinothalamic tract: pain and temp Anterior spinothalamic tract: general tract |
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What are the three major circumferential arteries, from where do they emerge and to what neuroanatomical structures do they provide blood?
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MCA, ACA, and PCA.
ACA- main branches are orbital, frontopolar, callosomarginal, and pericallosal arteries. Give blood to frontal an parietal lobes. MCA- gives blood to frontal, temporal, and parietal lobes. MCA gives off lateral and medial lenticulostriate branches. Includes the primary auditory cortex The medial lenticulostriate artery supplies blood to the globus pallidus, the posterior internal capsule, and medial ventral area of the thalamus. The lateral lenticulostriate artery supplies the entire pulvinar and caduate nucleus PCA- Gives blood to the temporal and occipital lobes, including the primary visual cortex |
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Supratentorial Space
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Contains the cerebral cortex, the space above the tentorium
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Infratentorial Space
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Contains the cerebellum and brainstem, the space below the tentorium
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Describe the anterior chamber
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-Includes the area between the cornea and the iris
-Filled with aqueous humor, a fluid similar to CSF which is produced by the choroid plexus of the ciliary processes. -Flow: pupil-->posterior chamber -drains into venous system canal of Schlemm -maintains intraocular pressure (major function of aqueous humor) -constant replacement of aqueous humor |
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Describe the posterior chamber
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-Includes the area between the iris and the suspensory ligament.
-In front of posterior cavity -Also contains aqueous humor -also helps maintain intraocular pressure |
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Anterior Segment
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-Contains anterior and posterior chambers
-functions to: refract light rays and image on retina -includes: -iris, cornea, lens -aqueous humor, ciliary body -suspensory ligaments |
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Posterior Segment
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-Posterior Cavity
microfibrillar mesh/net-like structure -contains hyaloid membrane, vitreous humor, retina, choroid, optic nerve -vitreous humor (jelly-like) (it is not replaced) -helps maintain eyeball shape and cushions -kepps eyeball from collapsing |
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How do cones and rods play a role in photosensation?
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Cone
-phototopic cones -blue (445), green (535), red (570) -function in bright day light -sharp visual acuity/color vision -high temporal resolution Rods -scotopic -mediate night vision -function in dim light -differentiate black, white, gray -detect movement, shapes |
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Describe the neuronal pathway of visual information
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1) The refraction of light rays by the lens and cornea
2) the conversion of electromagnetic energy in light by the retinal photoreceptor cells into nerve impulses 3) the transmission of impulses from the retinal photoreceptors to the visual cortex in the occipital lobe 4)the perception of visual images in the primary visual cortex -The primary visual cortex projects to the adjacent visual association region, where visual information is elaborated. |
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Where are the major neurons located with respect to first, second, third order neurons?
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1st order- spiral ganglia
pass through internal auditory meatus 2nd order-cochlear nuclei pontomedullary junction 3rd order-thalamus (medial geniculate nucleus) Extends: cochlear nucleus-primary auditory cortex |
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What muscles innervate or move the eyeball? What cranial nerves innervate the muscles of the eye?
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3, 4, and 6 cranial nerves that move the eyes
1. Lateral rectus - moves the eye outward, away from the nose 2. Medial rectus - moves the eye toward the nose 3. Superior rectus - moves the eye upward 4. Inferior rectus - moves the eye downward 5. Superior oblique -has several actions on the eye , but primarily causes the eye to twist outward |
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Which specific sensory system mediates pain, temperature, crude touch, and pressure?
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-Anterior Lateral System
-Protopathic system |
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What specific system mediates fine discrimination, stereognosis, and two point discrimination?
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-DCML
-epicritic system |
