Term
| Which corticobulbar pathways are unilateral and crossed? |
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Definition
| motor to lower face, tongue, uvula/soft palate, trapezius |
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Term
| are fasiculations indicative of an upper or lower motor neuron? |
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Definition
| lower - indicate hypersensitivity to ACh |
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Term
| What is Weber's syndrome (anterior alternating hemiplegia)? |
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Definition
| lesion of the ventral midbrain that impacts corticospinal with/without corticobulbar tracts, and the NERVE of CN III. ipsilateral ophthalmoplegia, contralateral hemiplegia of body +/- contralateral hemiplegia of lower face, tongue, trapezius. |
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Term
| What is Claude's syndrome? |
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Definition
| Weber's syndrome (with corticobulbar involvement) + contralateral ataxia. |
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Term
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Definition
| rapid jerky focusing on new objects |
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Term
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Definition
| tracking followed by jerking as you focus on another object |
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Term
| what controls the occulomotor nuclei during vergence? |
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Definition
| The supraocculomotor nucleus. |
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Term
| Describe the neural pathways used to look to the left |
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Definition
| UMN's from RIGHT frontal eye field -> LEFT paramedial pontine reticular formation (PPRF) -> left abducens nucleus L. abucens nucleus activates L. CN VI and projects to R. occulomotor nucleus via MLF, to activate R. CN III (rectus medius) |
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Term
| describe process of looking up? |
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Definition
| BILATERAL frontal eye fields -> rostral insterstitial nucleus of the MLF (medial longitudinal fasciculus) -> occulomotor/trochlear nuclei |
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Term
| What is Perinaud syndrome? |
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Definition
| paralysis of upward gaze (compression of superior colliculus - major visual reflex/control area) |
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Term
| What is the reticular formation? |
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Definition
| A heterogenous population of small "dustlike" brainstem nuclei that control muscle tone, respiration, consciousness, pain perception, cardiovascular function, motor coordination, . |
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Term
| What connects the pons to the cerebellum? Ipsilateral or contralateral? |
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Definition
| Pontocerebellar fibers (visible ventrally) connect L. pons to R. cerebellum, via middle cerebellar peduncle. |
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Term
| What are symptoms of middle alternating hemiplegia? |
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Definition
| ipsilateral VI ophthalmoplegia, contralateral somatic hemiplegia. If corticobulbar involvement, no tongue/trap function contralateral (lower face is spared; VII fibers have already left corticobulbar tract at level of abducens nucleus). |
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Term
| What nuclei does the riMLF project to? |
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Definition
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Term
| What is the labyrinthine artery a branch of? Which CN's does it supply? |
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Definition
| AICA -> supplies VII and VIII |
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Term
| What's a Marcus Gunn pupil? |
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Definition
| Relative Afferent Pupil Defect - eye appears to dilate (really just reacts to no stimulation) when light is moved from unaffected to affected eye. |
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Term
| argyll robertson syndrome |
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Definition
| no pupil constriction during light tests, but constriction present during accomodation. B/c lesion is in pre-tectum (which controls E-W nucleus during light response), and frontal eye fields can bypass pretectum during accomodation constriction |
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Term
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Definition
| damage to descending sympathetics (->superior cervical ganglion -> internal carotid plexus) causes ptosis (superior tarsal muscle), anhydrosis, pupillary constriction |
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Term
| posterior communicating artery aneurism |
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Definition
| loss of pupillary control but not occulomotor control - pupillary fibers are central in CN III |
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Term
| What are the three parts of the trigeminal nucleus? Functions? |
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Definition
| Mesencephalic carries proprioceptive info from mastication muscles with NO intervening ganglion (thus these are 1ary neurons); principle nucleus carries MVP from face; spinal nucleus temperature/ crude touch from entire face/oral cavity (inputs from V, VII, IX, X) |
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Term
| how does the cortex receive proprioceptive info about the masseter muscles? |
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Definition
| 1ary neurons in mesencephalic nucleus -> trigeminal motor nucleus -> contralateral ventral trigeminothalamic tract |
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Term
| What is the difference between the ventral and dorsal trigeminothalamic nuclei? |
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Definition
Ventral = face information + oral pain/crude touch
dorsal = oral MVP |
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Term
| What are the inputs to spinal nucleus of V? |
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Definition
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Term
| Difference in symptoms between unilateral corticobulbar lesion and unilateral motor nucleus of V lesion? |
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Definition
corticobulbar - no effect, input is bilateral to motor nucleus
motor nucleus - ipsilateral paralysis of mastication muscles |
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Term
| What are the inputs for the superior salivatory nucleus? |
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Definition
| affarents from CN's V, VII, IX, X (taste, pain, temperature -> tears and saliva) |
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Term
| What is the innervation pattern for the face musculature (crossed/uncrossed, unilateral/bilateral)? |
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Definition
Upper face is bilateral (includes orbicularis oculi)
lower face is unilateral and crossed |
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Term
| What neurons affect the motor nucleus of VII to drive the corneal (blink) reflex? |
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Definition
visual stimuli -> superior colliculus
tactile stimuli -> trigeminal ganglion |
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Term
| what drives the stapedius reflex? |
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Definition
| superior olivary nucleus -> motor nucleus of VII |
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Term
| What is the auditory pathway? |
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Definition
VIII spiral ganglion -> ventral cochlear nucleus -> lateral lemniscus -> inferior colliculus -> medial geniculate nucleus of thalamus.
BRANCH: Ventral coch. n. -> superior olive -> trapezoid body (crossing structure) -> contralateral lateral lemniscus |
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Term
| Which nuclei and pathways right the body/neck during a fall? |
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Definition
body: lateral vestibular nucleus -> ipsilateral vestibulospinal tract -> ipsilateral muscles
neck: medial vestibular nucleus -> ipsilateral medial vestibulospinal tract -> ipsilateral cervical neurons -> BIlateral cervical muscles |
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Term
| What are the functions of the pretectum? Superior colliculus? |
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Definition
pretectum -> pupillary light response/lens accomodation
superior collicululs-> head turning, reflexive eye movements, vertical gaze (compression leads to parinaud syndrome)
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Term
| What is most at risk of being injured in glaucoma? |
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Definition
| optic nerve just caudal to optic disc |
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Term
| What vasculature supplies the inner retina? Outer? |
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Definition
| Inner-> central retinal vein. Outer ->posterior ciliary arteries which form the choroid plexus (these arteries also supply iris and ciliary bodies) |
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Term
| What connections are made in the outer plexiform layer? |
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Definition
| horizontal-photoreceptor-bipolar |
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Term
| What cell connections are made in the inner plexiform layer? |
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Definition
| ganglion-bipolar-amacrine |
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Term
| who can absorb aqueous humour? |
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Definition
| canal of schlemm, iris (uveoscleral outflow), trabecular meshwork |
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Term
| what are the three glial populations of the retina? |
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Definition
| muller glia (electrolyte homeostasis, contribute to limiting membranes), microglia, astrocytes |
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Term
| what is the function of the melanopsin-containing ganglion cells? |
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Definition
| circadian rhythm + pupillary light reflex |
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Term
| explain one reason why the neurons can show similar details in different lighting conditions |
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Definition
| "on" and "off" cones respond to CHANGES (increase and decrease, respictively) in the amount of light |
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Term
| Which photoreceptors increase neurotransmitter secretions during increasing photostimulus? Which bipolar neurons depolarize in response to photoreceptor decrease in neurotransmitter release? |
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Definition
| ALL photoreceptors hyperpolarize during increasing photostimulus, and produce LESS neurotransmitter (glutamate). Bipolar neurons connected to ON cones and to rods depolarize when the photoreceptor to which they are connected is stimulated by light (this causes decrease in photoreceptor neurotransmitter release) |
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Term
| what is the effect of a depolarized amacrine cell on cone ON and OFF ganglion cells? |
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Definition
| inhibits OFF ganglion and forms gap junctions with (excites) ON ganglion |
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Term
| what does it mean if a ganglion cell has an ON center/OFF surround pattern of stimulation? |
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Definition
| Bright center stimulus and dark annulus stimulus maximally stimulates the ganglion cell |
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Term
| To which thalamus cells do the midget, parasol, and small-field bistratified cells project? Which lamina? What are the functions of the parasol vs. midget cells? |
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Definition
| To the parvocellular (dorsal lamina), magnocellular (ventral lamina), and (not known) layers of the lateral geniculate nucleus of the thalamus. Parasol cells = where is it. movement sensitive, low acuity. Midget = what is it. Color sensitive, high acuity. |
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Term
| which ganglion cells are sensitive to red/green or blue light? |
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Definition
| midget-> red/green, small-filed bistratified -> blue |
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Term
| what is the primary target of the ganglia cells? |
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Definition
| the dorsal lateral geniculate nuclei of the thalamus |
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Term
| describe the pathway of information from a light beam on the left of a person's head to the thalamus |
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Definition
| crosses to L. nasal and R. temporal retina. Goes through both optic nerves, and at the chiasm the L. nasal fibers cross to the R. dorsal lateral geniculate nucleus, and the R. temporal fibers stay uncrossed |
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Term
| Describe the organziation of the visual cortex |
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Definition
| central vf-> caudal; peripheral -> rostral; R. visual world -> L cortex; superior visual world -> inferior bank of calcarine fissure |
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Term
| What will a lesion of the R. inferior and superior banks of the calcarine fissure produe? |
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Definition
| contralateral homonymous hemianopsia with macular sparing |
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Term
| which layers of visual cortex do dorsal lateral geniculate nuclei neurons project to? How is occular information kept separate from the other eye? |
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Definition
| project to layers IV+ VI; occular information is separated into adjacent occular dominance columns |
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Term
| What are the orientations of the utricle and saccule? |
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Definition
| The utricle is oriented ~ horizontally, and the saccule is oriented vertically. |
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Term
| Which IX/X nuclei have 1ary neurons for taste? Baroreception/chemoreception? |
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Definition
Superior = general sensory
Inferior = baro/chemo, taste |
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Term
| to which neurons/muscles do the caudal nuc. solitarius neurons project to and modulate in the case of a change in either arterial pressure or change in arterial pH? |
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Definition
| To X motor (activates these in case of high blood pressure), to preganglionic sympathetics (inhibits these in case of high blood pressure; effects on both heart rate and systemic vascular resistance), and to intercostal muscles (changes respiration) |
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Term
| Which fibers are handled by the ventral vs. dorsal trigeminothalamic tracts? Are they crossed or uncrossed? |
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Definition
| The ventral tract handles most general sensory information from from the face and is CROSSED. The dorsal tract handles information from the oral cavity and is UNCROSSED. |
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Term
| To which nucleus does the solitareothalamic tract project? Crossed or uncrossed? |
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Definition
| to the VPM of the thalamus, uncrossed. |
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Term
| Which CN XI muscle is primarily affected ipsilaterally by an UMN lesion? Contralaterally? |
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Definition
| UMN lesions affect the trapezius contralaterally and the SCM ipsilaterally. |
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Term
| What is the organization of the LGN and the visual cortex relative to the retina? |
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Definition
| LGN keeps the same lateral orientation as the retina, visual cortex has crossed orientation relative to retina (orientations WITHIN one hemisphere of visual cortex is that of visual world, but remember that the L. visual cortex receives R. visual world info) |
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Term
| Which cell populations in the central visual pathway have concentric (center/surround) receptive fields? |
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Definition
| ganglion cells, dLGN cells, layer IVc cells of visual cortex |
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Term
| Which muscles innervated by CN X have unilateral UMN innervation? |
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Definition
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