Exam III Flashcards
when light enters the eye, what happens?
the light is INVERTED and REVERSED
how do the superior and inferior visual fields project onto the retina?
(1) superior: projects onto the lower retina
(2) inferior: projects onto the upper retina
how do the right and left visual fields project onto the retina?
(1) right: left side of the retina
(2) left: right side of the retina
where does the normal visual field extend?
it extends more to the periphery than it does medially (or toward our nose), and extends more inferiorly than superiorly
what is the central fixation for each eye?
fovea
what area of the retina has the highest visual acuity?
fovea
what surrounds the fovea?
macula
what forms the optic disc?
axons leaving the retina
where is the blind spot located in the eye
where the optic disc is; 15 degrees lateral and slightly inferior to the central fixation point
what are the 3 layers of the retina? what is found in each layer?
(1) outermost: contains photoreceptors (rods and cones)
(2) middle: bipolar cells
(3) innermost: ganglion cells (parasol and midget cells)
where do the photoreceptors synapse?
bipolar cells
where are the cones primarily located? what is their function?
(1) fovea and macula
(2) high resolution visual images and color
where are the rods primarily located? what is their function?
(1) periphery of the retina
(2) vision in low light; provide low resolution visual images, and do NOT detect color
what is the function of the bipolar cells?
(1) receive input from the photoreceptors
(2) send input to ganglion cells
what do parasol cells respond to? what can be said about the size of their cell bodies and diameter of their fibers?
(1) gross stimulus features and movement
(2) LARGE cell bodies and LARGE diameter
where do parasol cells project to?
magnocellular layers of the LGN (lateral geniculate nucleus) of the thalamus
what do midget cells respond to? what can be said about the size of their cell bodies and diameter of their fibers?
(1) fine visual details and colors
(2) SMALL cell bodies and SMALL diameter
where do midget cells project to?
parvocellular layers of the LGN of the thalamus
where does the optic nerve receive input from?
retinal ganglion cells
what information is carried by the optic nerve?
(1) the entire visual field for the right eye is carried in the right optic nerve
(2) the entire visual field for the left eye is carried in the left optic nerve
what fibers cross in the optic chiasm?
nasal fibers (responsible for the lateral part of our vision)
what information does the RIGHT optic tract carry?
(1) info from the right side of the retina in the right eye
(2) info from the right side of the retina in the left eye
what would damage to the optic tract result in?
contralateral homonymous hemianopsia
what would damage to the optic chiasm result in?
bitemporal hemianopsia (AKA tunnel vision)
what do the optic tracts wrap around? where do they synapse?
(1) midbrain
(2) LGN of the thalamus
the RIGHT LGN recieves infromation from what visual field?
left visual field (right hemiretinas of both eyes)
which layers are the magnocellular layers of the LGN? where do these layers recieve input from?
(1) Layers 1-2
(2) parasol cells of the retina
which layers are the parvocellular layers of the LGN? where do these layers recieve input from?
(1) Layers 3-6
(2) midget cells of the retina
a minority of fibers in the optic tract bypass the LGN and enter what areas of the thalamus? what pathway does this form?
(1) superior colliculus AND pretectal area
(2) extrageniculate visual pathways
what area of the thalamus is involved with the pupillary light reflex?
pretectal areas
what areas of the thalamus is involved in directing visual attention and eye movements toward visual stimuli?
(1) pretectal areas
(2) superior colliculus
what are optic radiations?
axons leaving the LGN that sweep over the lateral ventricle and fan out to the Primary Visual Cortex
what would damage to the optic radiations result in?
homonymous contrateral visual field loss
left optic radiations carry information from what side of the body?
right side
right optic radiations carry information from what side of the body?
left side
the inferior optic radiations carry information from where?
SUPERIOR VISUAL FIELD
the superior optic radiations carry information from where?
INFERIOR VISUAL FIELD
damage to the temporal lobe causing damage to meyer’s loop (inferior optic radiations) results in what?
contralateral superior quadrantanopia (pie in the sky)
where do superior optic radiations terminate?
upper bank of the calcarine fissure
where do inferior optic radiations terminate?
lower bank of the calcarine fissure
damage to the parietal lobe that caused damage to the superior optic radiations results in what?
contralateral inferior quadrantanopia (pie on the floor)
where is the primary visual cortex?
upper and lower banks of the calcarine fissure
what is the name of the upper bank of the calcarine fissure?
cuneus
what is the name of the lower bank of the calcarine fissure?
lingula
where are the fovea and macula represented in the brain?
occipital pole of calcarine fissure
where is peripheral vision represented in the brain?
anterior along calcarine fissure
where in the higher-order visual association cortex do the magnocellular parasol cells transmit?
DORSAL PATHWAYS
dorsolateral parieto-occipital cortex
where in the higher-order visual association cortex do the parcocellular and interlaminar midget cells transmit?
VENTRAL PATHWAYS
inferior occiptiotemporal cortex
in regards to visual processing, what do the dorsal pathways transmit?
motion and spatial analysis
in regards to visual processing, what do the ventral pathways transmit?
form and color
what is often used to measure visual acuity?
Snellen eye chart (at 20 feet)
what are the two divisions of visual disturbances?
(1) negative phenomena: region of vision a person can’t see
2) positive phenomena: extra things are added to the visual field (lights, colors, shapes
what is a formed positive phenomena? where in the brain does this phenomena arise?
(1) visual hallucinations
(2) inferior temporo-occipital visual association cortex
what is release phenomena?
occurs in patients who have undergone visual deprivation where they see people, animals in the region of visual loss
what would cause a right monocular visual loss?
(1) lesion to the right optic nerve (or lesion of entire retina)
(2) glaucoma, optic neuritis, tumors, trauma
what would cause a scotoma?
(1) damage to small part of the retina
(2) retinal infarcts, hemorrhages, degeneration, infections
what would cause a bitemporal hemianopsia?
(1) lesion to the optic chiasm
(2) pituitary adenoma, hypothalamic glioma, tumor pressing on the optic chiasm
what would cause contralateral homonymous hemianopsia?
(1) lesion to the optic tract, LGN; wiped out entire optic radiations or primary visual cortex
(2) tumors, infarct to artery, demyleniation to tracts or radiations
what would cause contralateral inferior quadrantanopia?
(1) lesion to superior optic radiations or superior upper bank of the calcarine fissure
(2) infarct to blood supply (superior division of MCA or PCA)
what would cause contralateral superior quadrantanopia?
(1) lesion to inferior optic radiations superior and lower bank of the calcarine fissure
(2) infarct to an artery
what is macular sparing?
where partial lesions to the visual field occur where the central (fovea / macula) visual field is spared
what would cause a central scotoma?
(1) a lesion to just the occipital pole (fovea and macular area)
(2) head injury to the back of the head at bottom of the occiput
what is the primary source of blood flow for the retina?
opthalmic artery
what are 3 possible causes for reduced blood flow to the retina?
(1) embolus
(2) stenosis
(3) vasculitis
what are the 2 main branches of the retinal artery
(1) superior branch
(2) inferior branch
an occlusion of the the superior or inferior branch of the retinal artery can cause what?
altitudinal scotoma
what is an amaurosis fugax? how does it present?
(1) transient occlusion of the superior or inferior branch of retinal artery
(2) patients report browning out (shade being pulled over eye)
what is an amaurosis fugax a warning sign for?
similar to a TIA (but for the eye); a common cause is an ipsilateral stenosis of the internal carotid artery
what supplies blood flow to the optic nerves, optic chiasm, and optic tracts?
numerous small branches off ACA and MCA (rarely see clinically significant infarcts)
what supplies blood to the LGN? what decificts might present with a lesion to this area?
(1) anterior choroidal artery, PCA, thalamogeniculate artery
(2) contralateral homonymous hemianopsia and contralteral hemiparesis
what lobe do the superior optic radiations pass through? which arteries supply blood to this structure?
(1) parietal lobe
(2) superior divisions of the MCA
what lobe do the inferior optic radiations pass through? which arteries supply blood to this structure?
(1) temporal lobe (meyer’s loop)
(2) inferior divisions of the MCA
what supplies blood to the primary visual cortex? what deficit might a patient with this infarct present with?
(1) PCA
(2) contralateral homonymous hemianopsia
KNOW CRANIAL NERVES, ROMAN NUMERALS, AND FUNCTION
KNOW CRANIAL NERVES, ROMAN NUMERALS, AND FUNCTION
the brainstem is composed of structures?
the midbrain, pons, and medulla
where is the rostral limit of the brainstem?
midbrain / diencephalic junction
where is the caudal limit of the brainstem?
cervicomedually junction
the tectum (in the midbrain) of the brainstem is made up of what structures?
(1) superior colliculi
(2) inferior colliculi
where are the cerebral peduncles of the brainstem located?
midbrain
where in the brainstem are the pyramids and pyramidal decussation located?
medulla
where are the cerebellar peduncles of the brainstem located?
pons
where does CN 1 (olfactory) exit?
cribiform plate
where does CN 2 (optic) exit?
optic canal; travels around midbrain to LGN)
all crainal nerves 3-12 leave the brainstem either ventrally or ventral-laterally with what exception?
CN 4 (exits dorsal midbrain)
where does CN 3 (oculomotor) exit?
superior orbital fissure; travel through interpenduncular fossa of midbrain
where does CN 4 (trochlear) exit?
superior orbital fissure
where does CN 5 (trigeminal) exit?
mnemonic SRO
(V1) superior orbtial fissure
(V2) foramen rotundum
(V3) foramen ovale
where does CN 6 (abducens) exit?
superior orbital fissure
where does CN 7 (facial) exit?
travels through internal auditory canal and EXITS through stylomastoid foramen
where does CN 11 (accessory) exit?
jugular foramen (laterally from multiple rootlets along upper cervical cord)
where does CN 12 (hypoglossal) exit?
hypoglossal foramen (travels between pyramid and olive of the medulla)
where does CN 8 (vestibulocochlear) exit?
travels through internal auditory canal and ENTERS auditory canal
where does CN 9 (glossopharyengeal) exit?
jugular foramen
where does CN 10 (vagus) exit?
jugular foramen
mature cranial nerves have how many motor and how many sensory columns?
3 motor and 3 sensory
where do olfactory nerves synapse?
olfactory bulb and carry information via olfactory tract
what is anosmia? what can cause this condition?
(1) olfactory loss of smell
2) damage to olfactory nerve; secondary to head trauma, infection, PD, Az, intracranial lesions (tumors
where is the nucleus of CNs 3 and 4 located?
midbrain
where is the nucleus of CN 6 located?
pons
what is trigeminal neuralgia (AKA tix douloureux)?
(1) trigeminal nerve dysfunction; brief severe pain provoked by chewing, shaving
(2) unknown cause; can occur in MS patients
an UMN lesion to the facial nerve results in what?
weakness of the lower part of the face, but the forehead is spared (may have UE weakness and other deficits)
a LMN lesion to the facial nerve results in what?
unilateral weakness from top to bottom (localized)
what is LMN weakness of the facial nerve known as?
Bell’s Palsy
what is the dividing line between the external ear and middle ear?
tympanic membrane
what are the three ossicles of the middle ear?
(1) malleus
(2) incus
(3) stapes
what bone attached to the tympanic membrane?
malleus
what bone attaches to the oval window?
stapes
what is the purpose of the tensor tympani and stapedius muscles?
attach to the ossicles and regulate sound energy (dampen loud sounds)
what structures are contained within the inner ear?
(1) bony labyrinth
(2) membranous labyrinth
(a) cochlea (organ of corti)
(b) vestibule (saccule and utricle)
(c) semicircular canals
what are the two main ducts of the cochlea? what are their functions?
(1) scala vestibuli: sound vibrations enter here from the oval window
(2) scala tympani: found at the end of the apex, spiral around and ends at round window
the scala vestibuli and scala tympani contain what type of fluid?
perilymphatic fluid
the scala media (or central duct) contains what type of fluid?
endolymphatic fluid
where are higher frequency sounds managed in the ear?
near the oval window
where are lower frequency sounds managed in the ear?
near apex of the cochlea
the scala media is bound by what two membranes?
(1) basilar membrane
(2) Reissner’s membrane
what is the function of the organ of corti?
receptor organ responsible for hearing (converts auditory signals into nerve impulses)
how is information relayed to the organ of corti?
deflection of hair cells and vibrations of the basilar membrane are relayed to the organ of corti
how is sound transmitted through the outer, middle, and inner ear?
(1) Outer ear: air pressure causes the tympanic membrane to vibrate
(2) Middle ear: this causes oscillatory movements of the stapes against the oval window
(3) Inner ear: endolymph inside the cochlea causes vibration of the basilar membrane
(4) Organ of Corti: hair cells are deflected and transmit information to CN VIII
where do the contralateral auditory tracts project to?
(1) RAS to the cortex
(2) spinal cord in response to loud sounds
(3) cerebellum in response to sudden noise
is unilateral hearing loss typically seen with a lesions in the brain?
no; there are decussations at multiple levels and information ascends bilaterally; a lesion of the cochlear nuclei could cause unilateral hearing loss
what is the main blood supply to the vestibule and cochlea of the ear?
labyrinthine artery (usually a branch off AICA)
the bony labyrinth of the vesibular part of the ear contains what? and what type of fluid?
(1) three semicircular canals
(2) vestibule
(3) perilymph
the membranous labyrinth of the vesibular part of the ear contains what? and what type of fluid?
(1) three semicircular canals
(2) utricle and saccule
(3) endolymph
what is the purpose of the semicircular canals? how are these positioned?
respond to angular or rotational movement of the head Positions (1) R and L lateral (2) L anterior, R posterior (3) L posterior, R anterior
where is the ampulla located? what structure does it contain?
(1) bulge at the base of the semicircular canals
(2) contains the crista ampullaris
what plane of motion does the utricle relay information about the position of the head?
in response to gravity in the horizontal plane (ex. riding in a car)
what plane of motion does the saccule relay information about the position of the head?
in response to gravity in the vertical plane (ex. riding in an elevator)
what is the primary sensory structure located within the urticle and saccule?
macula
what is the purpose of the hair cells found within the utricle and saccule?
convert displacement of head movement into neural firing
if there is a lesion to the vermis in the cerebellum, what can occur?
gait ataxia and trunk instability
if there is a lesion to the flocculus in the cerebellum, what can occur?
impaired ability to keep vision stable while the head is being moved (VOR)
what are the 2 mechanisms for motor output of the vestibulochochlear nerve?
(1) VOR: keep vision stable while the head is being moved
(2) VSR: keep head and body stabilized
what can cause conductive hearing loss?
(1) otitis
(2) tympanic membrane perforation
what can cause sensorineural hearing loss?
(1) disorders of the cochlea or CN 8
(2) exposure to loud sounds
(3) Meniere’s disease
(4) tumor
what is the gold standard test for hearing loss?
audiometry
what clinical assessment is used to determine conductive hearing loss?
Rinne Test
what clinical assessment is used to determine sensorineural hearing loss?
Weber Test
where could a lesion be present to cause vertigo?
anywhere along the vestibular pathway
what is BPPV?
benign paroxysmal positional vertigo
what is vestibular neuritis? what does this condition present with?
(1) inflammation of the vestibular ganglia or nerve
(2) intense vertigo for days and loss of postural control from weeks to months
what is Meninere’s Disease? what does this condition present with?
(1) excessive fluid and pressure in the endolympahic system
(2) recurrent episodes of vertigo accompanied by fluctuating hearing loss and tinnitus
what is acoustic neuroma? what does this condition present with?
(1) vestibular schwannoma (tumor)
(2) hearing loss, tinnitus, vertigo, LOB
how will a patient following a lesion to the hypoglossal nucleus?
ipsilateral weakness of the tongue (UMN lesion would present with contralateral lesion to the tongue)
what is dysarthria? what can cause this condition?
(1) abnormal articulation of speech
(2) CVA, MS, brainstem lesions, lesions of cerebellar and BG pathways
what is dysphagia? what can cause this condition?
(1) impaired swallowing
(2) neoplasms, esophageal strictures, neural components
what is the main function of olfactory nerve?
olfaction (smell)
what is the main function of optic nerve?
vision
what is the main function of oculomotor?
elevate eye lid; all eye movements except abduction and downward medial rotation; constricts the pupil
what is the function of the trochlear nerve?
downward medial rotation of the eye
what is the function of the trigeminal nerve?
facial sensation; muscles of mastication
what is the function of the abducens nerve?
abducts the eye
what is the function of the facial nerve? (3)
(1) facial expression
(2) taste of anterior 2/3 of tongue
(3) mandibular and sublingual salivary glands; lacrimal gland (and others of nose and palate)
what is the function of the vestibulocochlear nerve? (2)
(1) hearing
(2) position and movement sense
what are the functions of the glossopharyngeal nerve? (3)
(1) swallowing
(2) parotid gland innervation
(3) taste posterior 1/3 of tongue
what are the functions of the vagus nerve?
(1) parasympathetic to most organs
(2) laryngeal muscles (voice)
(3) pharyngeal muscles (swallowing)
(4) conductive system of the heart
what is the function of the spinal accessory nerve?
innervates the SCOM and traps (head turning)
what is the function of the spinal hypoglossal nerve?
intrinsic and extrinsic muscles of tongue
what does the edinger westphal nucleus control?
parasympathetic nucleus of CN 3; causes pupil constriction
what might a patient present with following a lesion to the oculomotor nerve? (4)
(1) eye deviation laterally
(2) diplopia
(3) ptosis
(4) impaired pupillary light and accommodation reflexes
what might a patient present with following a lesion to the trochlear nerve?
difficulty moving eye downward and laterally
what might a patient present with following a lesion to the abducens nerve?
(1) difficulty turning eye outward
(2) medial strabismus
(3) diplopia
what are long tracts in the brain stem?
the long motor and sensory tracts
what is the periaqueductal gray area of the midbrain responsible for? what tract is this a part of?
pain modulation (via spinothalmic tract)
what is the reticular formation responsible for? what tract is this a part of?
conciousness, sleep / wake cycles (via reticulospinal tract)
what is the substantia nigra responsible for?
creates dopamine in the BG
what is the function of the rostral reticular formation?
alertness, consciousness, and arousal
what is the function of the caudal reticular formation?
reflexes, motor, and autonomic functions (respiration and circulatory control)
what systems are involved with consciousness? (4)
(1) sensory
(2) motor
(3) memory
(4) emotional
regarding the subcortical arousal system, what neurotransmitters are used in the upper brain stem neurons? where do their neurons project?
(1) norepinephrine
(2) serotonin
(3) dopamine
Projects to:
-cortical and subcortical forebrain
regarding the subcortical arousal system, what neurotransmitters are used in pontomesencephalic reticular formation neurons? where do their neurons project?
(1) acetylcholine
(2) glutamate
Projects to:
-thalamus, hypothalamus, basal forebrain
regarding the subcortical arousal system, what neurotransmitters are used in posterior hypothalamic neurons? where do their neurons project?
(1) histamine
(2) orexin
Projects to:
-cortical and subcortical targets
regarding the subcortical arousal system, what neurotransmitters are used in the basal forebrain neurons? where do their neurons project?
(1) acetylcholine
Projects to:
-cerebral cortex
regarding the subcortical arousal system, what neurotransmitters are used in the rostral thalamic intralaminar nuclei and medial thalamic nuclei? where do their neurons project?
(1) glutamate
Projects to:
-cerebral cortex
damage to what areas of the brain often results in a coma? (2)
(1) upper brain stem
(2) widespread, bilateral damage to the cortex
what are the first 4 stages of sleep considered? what neurotransmitters control these phases of sleep?
(1) nonREM sleep
(2) neurons of the raphe nuclei release serotonin
what are the 5th stage of sleep considered? what neurotransmitters control these phases of sleep?
(1) REM sleep
(2) neurons of the locus cereleus release norepinephrine
damage to what areas of the brain often results in death?
lower brain stem
what nucleus is responsible for respiration and circulatory control? where is it located?
nucleus soltarius of the medulla
where in the brain is responsible for autonomic respiratory control? what about voluntary respiratory control?
(1) autonomic: medulla
(2) voluntary: forebrain
