Neuroanatomy Exam 2

direct light reflex What happens if you shine light in the one eye, it goes down the optic tract to get to the EW nucleus and comes back so that the same eye constricts

constriction of pupil in same eye that shine light in

trigeminal nerve nucleus

continuation of the substantia gelatinosa of the spinal cord

Horizontal canals and utricle

control horizontal eye movement

Vertical semicircular canals & saccule

control vertical eye movement

stapedius muscle

controlled by facial nerve, facial motor nucleus does similar action as the tensor tympani of the eardrum - keeps oval window membrane from vibrating too much

medial vestibulospinal

controls the vestibulocollic (head-righting) reflex found medially descended bilaterally - activated on one side and inhibited on the other orient head & neck -- excite or inhibit depending on direction

ganglionic cell axons

converge on the optic disc

trigeminal motor nucleus

cranial nerve nucleus Innervating the muscles of mastication (chewing)

facial nucleus

cranial nerve nucleus located at the same level as abducens nucleus, more anterior and lateral

abducens nerve

cranial nerve nucleus located in the caudal pons, controls the nerve that innervates the lateral rectus muscle

medial longitudinal fasciculus

crossed tracts with ascending and descending fibers; links CN III, IV, VI, VIII to integrate eye and head movements

peripheral vision

Detect low light in what area?

L/R up/down

conjugate movements of the eye (4)

Inferior cerebellar peduncles

connect cerebellum to medulla

Superior cerebellar peduncles

connects cerebellum to midbrain

consensual light reflex

constriction of pupil in contralateral eye that shine light in

(this is rare, but would affect dorsal and caudal medulla) gracile and cuneate tubercle spinal trigeminal nucleus and tract

which nuclei/tracts does the PSA supply? (2)

Motor -- anterior, closer to midline Sensory -- posterior

which part of the caudal brainstem is motor and which is sensory?

Motor -- medial (so lesion in the medial part would probably be motor) Sensory -- lateral (so lesion in lateral part would probably be sensory)

which part of the medulla/pons is motor and which is sensory?

Motor -- anterior Sensory -- posterior At this point it returns to the similar positioning that it had in the spinal cord

which part of the midbrain is motor and which is sensory?

basal plate (anterior) - motor alar plate (posterior) - sensory

which part of the spinal cord is motor and which is sensory?

superior --> out of inferior --> into

which peduncle carries info out of the cerebellum, which one carries info into?

same side

which side of semicircular canal is excited with angular movement?

central retinal artery (from ophthalmic artery, from internal carotid artery) optic nerve (CN II)

which structures enter and exit through the optic disc?

medial lemniscus (LE) ALS (spinothalamic) part of lateral lemniscus

which tracts do the quadrigeminal artery supply? (2)

corticonuclear frontopontine corticospinal medial lemniscus (head & UE)

which tracts does the PCA supply? (4)

Spinomesencephalic

while ALS is traveling to the thalamus, some fibers stop and branch to periaqueductal gray (important for pain processing)

spinotectal

while ALS is traveling to the thalamus, some fibers stop and branch to superior colliculus

pons proper (basilar pons)

anterior bulge of the pons

labyrinthine a. branches from AICA

blood supply vestibular and cochlear neurons and inner ear

conductive

bony ear ossicles disrupted, causing hearing loss

conjugate eye movements

both eyes moving the same way

amblyopia

brain fails to process vision in one eye If strabismus is untreated, then it is easier to use only one eye eventually, you will subconsciously just focus with one eye and ignore the other

peripheral retina

can see with this, but much less discriminating than the fovea

Inferior brachium of the inferior colliculus

carries information FROM the inferior colliculus (of the brainstem) TO the medial geniculate body of the thalamus

Meyer's loop

carries information from inferior retina (superior visual field) to the lingual gyrus of the visual cortex (lingual gyrus is below the calcarine sulcus) Arcs rostrally into temporal lobe before traveling caudally to the lingual gyrus

lateral lemniscus

carrying information from the cochlear nucleus once it hits its nucleus, has fibers going on either side (so if lesion at level of the nucleus would likely result in partial hearing loss)

bilateral fixed pupils, no reflex

central herniation, but pressure on EW nucleus would cause

hemiplegia

central herniation, but pressure on corticospinal tracts would cause

expressive aphasia

central herniation, but pressure on lateral parietal layer would cause

decorticate posture (arms flexed, legs extended) Above red nucleus

central herniation, but upper midbrain damage would cause

decerebrate posture (extensor input to arms and legs - vestibular influence) No longer have input from red nucleus

central herniation, but upper pontine damage would cause

cistern

cistern located anteriorly; contains CN III & upper portion of the basilar artery

Vitreaous body ( posterior chamber)

clear gelatinous mass filling eyeball, behind the lens and in front of the retina

spiral ganglion

cochlear ganglion

sensorineural

cochlear receptors or cochlear nerve disrupted, causing hearing loss

acoustic startle reflex (reticulospinal)

collaterals from lateral lemniscus to V & VII dampen sound sudden loud noise to RF to CN V and SC

geniculate ganglion

collection of sensory neurons of the facial nerve located in the facial canal of the head

oculomotor nerve -- CN III

exits at the medial edge of each crus (anteriorly) and passes through the interpeduncular fossa

trochlear n -- CN IV

exits in under the inferior colliculi (posteriorly) wraps around and goes through the ambient cistern, cavernous sinus, and through the superior orbital fissure

trochlear n.

exits just caudal to the inferior colliculus, marking the pons-midbrain junction on the posterior surface of the brainstem

Receiving bilateral input to upper face, but only contralateral up lower face upper face (frontalis and orbicularis oculi) --> both cortex innervate all other facial expression muscles -- only contralateral from cortex

explain the corticonuclear input to the face

internal acoustic meatus

facial nerve exits the skull via which foramina?

Apperceptive agnosia

fail to recognize shape & copy

frontopontine fibers

fibers given off by the corticospinal tract that terminate on basilar pons (on nuclei) and would then cross into middle cerebellar peduncle

Rhomboid fossa

floor of the 4th ventricle

perilymph

fluid between the semicircular duct and the bony labyrinth

aqueous body

fluid filled chamber in front of the lens

endolymph

fluid inside of the semicircular duct

smooth pursuit

for watching a specific target Head is still Eyes follow moving object Conjugate movement Voluntary

Meninges form a sleeve (include subarachnoid space) around the optic n. So there is CSF surrounding the optic nerve

form a sleeve (include subarachnoid space) around the optic n.

gracile and cuneate tubercles

found at the rostral end of the gracile and cuneate fasciculi, NOT inside 4th ventricle neurons come up and synapse in the here

sclera!

found behind the choroid

spinal trigeminal nucleus

found in the region that was considered the dorsal horn of the spinal cord (below the pyramidal decussation at the spinomedullary transition)

pontine nuclei

found in the ventral pons and responsible for coordinating movement

optic radiations

from the lower quadrant arch directly caudally through retrolenticular limb of internal capsule

caudal - heart rate, BP, blood pH rostral - taste

function of the caudal solitary nucleus? rostral?

proprioception

function of the mesencephalic nucleus

Edinger Westphal Nuclei (CN III)

general visceral efferent nucleus that provides parasympathetic neurons that go to eye and cause it to constrict & focus

the sup. colliculus

gets info about what is happening in periphery, but also moving eyes to that position (input from tectobulbar tract)

Parieto-, occipito-, and temporo-pontine fibers

info coming from different lobes of the brain down to the pontine nuclei basically info coming down to the cerebellum to provide more info about what you want to do in order to fine tune those things

proprioception, discriminative touch, and vibration

info that is carried by the dorsal column tracts

Lateral vestibulospinal tract

initiated by lateral and inferior vestibular nuclei vestibulospinal reflex ipsilateral - comes down to spinal cord and excite LE and trunk extensor muscles lean toward the side, extend same side gives feedback from the vestibular system → very important for balance

stapedius

inner ear muscle, dampens sounds by limiting vibrations

facial nerve

innervates muscles of the face taste, sensation around the ear has a parasympathetic component but MOST of the nerve carries motor neurons

abducens nerve -- this is the only thing the abducens does at the eye

innervates the lateral rectus muscle

CN III

innervation of the levator palpebrae superioris

CN VII close eyelid

innervation of the orbicularis oculi? function?

Medial longitudinal fissure (MLF)

interconnects extraocular (EO) nuclei and vestibular nuclei (so that things can work together)

MLF

interconnects the extraocular nuclei so that you can perform conjugate eye movements

pulse-step firing rate

jump in firing and then holds firm at firing rate seen by extraocular muscles

conjugate eye movements.

motor coordination of eyes that allows for bilateral fixation on a single object (both eyes moving together in same direction)

choroid plexus

suspended from tela choroidea

utricle

this otolith organ has a horizontal orientation

saccule

this otolith organ has a vertical orientation

Horner's syndrome!

this results when pathway from hypothalamus gets interrupted at some point

posterior spinocerebellar tract

this spinocerebellar tract enters at the inferior cerebellar peduncle

anterior spinocerebellar tract

this spinocerebellar tract enters at the superior cerebellar peduncle

ventral (parvocellular) pathways

visual association cortex that is located near the temporal lobe Perceive color & depth, discriminating things Recognize objects

cochlear nuclei inferior cerebellar peduncle (posterior) posterior spinocerebellar tract vestibular nuclei & nerve

which nuclei/tracts does the AICA supply? (4)

paramedian pontine reticular formation (PPRF)

what is horizontal eye movement managed by?

Ventral (parvocellular) pathways Dorsal (magnocellular) pathways

what is included in the visual association cortex?

down and out symptoms dilated pupil in affected eye

what is seen in oculomotor palsy?

middle cerebral artery (MCA), possibly the posterior cerebral artery (PCA), and anterior cerebral artery (ACA) overlap all the way around

what is the blood supply for the dorsal (magnocellular) pathways?

posterior cerebral artery (PCA) and middle cerebral artery (MCA)

what is the blood supply for the ventral (parvocellular) pathways?

Wernicke's - post-rolandic Broca's - pre-rolandic

what is the blood supply of Wernicke's & Broca's areas? (separate)

thalamogeniculate branches of the PCA

what is the blood supply to the LGN?

PCA (medial group of anterior branches off of posterior cerebral artery) Quadrigeminal artery

what is the blood supply to the midbrain? (2)

Posterior inferior cerebellar artery (PICA) Anterior inferior cerebellar artery (AICA)

what is the blood supply to the vestibulocochlear nuclei?

Innervated by CN III (EW) Function -- accommodation of the lens

what is the ciliary muscle innervated by? what does it do?

with a lesion of facial nerve as emerging from stylomastoid foramen, the mimetic muscles cannot function but if in the midbrain (corticobulbar level) you would be able to control upper part of the face (still losing lower face function)

what is the difference with a lesion of facial nerve as emerging from stylomastoid foramen, vs. if in the midbrain (corticobulbar level)?

crude touch, pain, temperature (ascending)

what is the function of the ALS?

motor control (descending)

what is the function of the corticospinal tract?

Important to parasympathetic visceromotor & sensory functions: -supplies the parotid gland -sensory component deals with regulation of BP and pH of blood processing info of taste from posterior ⅓ of tongue

what is the function of the glossopharyngeal nerve?

auditory processing

what is the function of the inferior colliculi?

proprioception; discriminative touch (somatosensation) - ascending

what is the function of the medial lemniscal system?

unconscious proprioception (ascending) Below cortical level, provides ongoing sensation about what is contributed to cerebellum so that fine motor control is being monitored

what is the function of the spinocerebellar tracts?

pyramid hypoglossal nucleus & nerve medial lemniscus

which nuclei/tracts does the ASA supply? (3)

Flex head → activate anterior canals, inactivate posterior canal

what movement would activate the anterior canal?

to the side Moving head to left would move the bone to the left, endolymph lags behind and moves the crista ampullaris, which causes an increase in firing of the hair cells

what movement would activate the horizontal canal?

Extend head diagonally → activate same side, inactivate opposite side superior canal

what movement would activate the posterior canal?

Vocalis - controls air through vocal cords

what muscle does the vagus nerve innervate?

superior oblique

what muscle of the eye does the trochlear n. innervate?

supply the intrinsic muscles of the tongue -Genioglossus -Hyoglossus -Styloglossus

what muscle(s) does the hypoglossal n. supply?

Oculomotor - medial rectus Abducens - lateral rectus excite contralateral abducens which will excite ipsilateral oculomotor; inhibit ipsilateral abducens move eyes in parallel opposite to head rotation

what muscles and nuclei are involved in the vestibulo-ocular reflex? how does this work?

Muscles of mastication (temporalis, masseter, medial & lateral pterygoid) tensor veli palatini tensor tympani (keeps eardrum from beating so hard, incus) part of digastric

what muscles are innervated by the trigeminal motor nucleus?

Superior oblique pulling down (trochlear) Lateral rectus pulling out (abducens) Both of these muscles are unopposed

what muscles are involved in down and out symptoms?

extraocular and intraocular muscles (besides lateral rectus and superior oblique)

what muscles do the oculomotor n. innervate?

facial

what other nerve travels with the ophthalmic division to get to the lacrimal gland

PAG

what parts of the brainstem do the spinomesencephalic fibers (of the spinothalamic tract) mainly go?

to the medulla and pons

what parts of the brainstem do the spinoreticular fibers (of the spinothalamic tract) mainly go?

sup colliculus

what parts of the brainstem do the spinotectal fibers (of the spinothalamic tract) mainly go?

the semicircular canals

what structure is affected in someone with nystagmus?

cerebellar tracts and the corticospinal tract

what tracts are found in the basilar pons?

(lateral to medial) parieto-, occipito-, and temporopontine fibers (most lateral) corticospinal corticobulbar frontopontine (most medial)

what tracts are found in the crus cerebri? (4)

spinothalamic, spinoreticular, spinomesencephalic tracts

what tracts are found within the ALS? (3)

in cerebellum --> affect same side way up --> getting info from both sides

what would a lesion to the anterior spinocerebellar tract in the cerebellum do? what if it was on the way up?

Tongue muscle points to the side of the lesion because the genioglossus muscle on the intact side pulls the tongue forward

what would be the effect of a hypoglossal n. lesion?

Don't have the connection between the oculomotor and the abducens Example: L eye is affected; during a right gaze the lateral rectus contracts but medial rectus contracts only intermittently while the lateral rectus contracts this is because it is not directly connected to the abducens nucleus, oculomotor is not directly affected may cause double vision when looking to the side still able to converge (crossing of the eyes) for close vision since nothing is wrong with oculomotor nuclei (and can communicate directly across the midline with each other

what would happen with a lesion to the MLF?

Preganglionic cell body in the Edinger Westphal nucleus Postganglionic cell body in the Ciliary ganglion Using it when in bright light and relaxed -- iris doesn't need to be open all the way, contracting ciliary muscles so they can properly see the images on the screen

when and what is used by the parasympathetic system in the eye?

accessory

which nuclei are associated with the accessory nerve?

solitary spinal trigeminal superior salivatory

which nuclei are associated with the facial nerve?

inferior salivatory solitary nucleus nucleus ambiguus

which nuclei are associated with the glossopharyngeal nerve?

hypoglossal nucleus

which nuclei are associated with the hypoglossal nerve?

Edinger-Westphal nucleus Oculomotor nucleus

which nuclei are associated with the oculomotor nerve?

mesencephalic principal sensory trigeminal motor spinal trigeminal (pars oralis, interpolaris, caudalis)

which nuclei are associated with the trigeminal nerve?

trochlear

which nuclei are associated with the trochlear nerve?

parasympathetic dorsal nucleus nucleus ambiguus solitary nucleus

which nuclei are associated with the vagus nerve?

sup vestibular (just in pons) med/lat/inf vestibular (pons & medulla) dorsal/ventral cochlear

which nuclei are associated with the vestibulocochlear nerve?

oculomotor nucleus and nerve (EW nucleus too?) trochlear red nucleus

which nuclei does the PCA supply? (3)

trigeminal mesencephalic nucleus superior and inferior colliculi trochlear nerve

which nuclei/nerve do the quadrigeminal artery supply? (2)

(supplies medial structures) corticospinal tract medial lemniscus abducens nucleus and nerve

which nuclei/tracts do the paramedian pontin branches of the basilar artery supply? (3)

(affects lateral structures) trigeminal motor & sensory nuceli and nerve facial motor nuclei

which nuclei/tracts do the pontocerebellar angle lesion supply? (2)

spinal trigeminal nucleus ALS vestibular nuclei solitary nucleus and tract nucleus ambiguus

which nuclei/tracts does the PICA supply? (5)

nystagmus

"nonvoluntary rhythmic oscillation of eyes"

vertigo

"perception of body movement" - seem like moving even though environment is not (self vs. environment)

1. anterior, medial 2. basilar pons 3. middle cerebellar peduncle

1. corticopontine fibers coming from the frontal lobe would be coming down through the (anterior/posterior) limb of the internal capsule and then remains (medial/lateral) 2. they then terminate on nuclei that are in the ....... 3. pontocerebellar fibers then cross the midline and go through what to get into cerebellum?

anterolateral sulcus

1st cervical nerve and CN XI (spinal) emerge from here (motor neurons)

Medial Longitudinal Fasciculus (MLF) of the pons

2 way communication between nuclei that supply extraocular muscles Coordinates eye movements so that the eyes will move together

internal arcuate fibers

2nd order neurons originating in the nucleus gracilis and the nucleus cuneatus and sweep across the central medulla as the sensory decussation to the other side of the medulla around/anterior to central gray matter

quadrigeminal plate (2 superior and 2 inferior colliculi)

4 swellings on the tectum (most dorsal region of the midbrain, dorsal to cerebral aqueduct)

oculomotor (CN III)

A proximal posterior cerebral artery aneurysm into the interpeduncular fossa may put pressure on which nerve?

the superior orbital fissure Oculomotor, trochlear, abducens, along with the ophthalmic division of the trigeminal n.

All cranial nerves innervating extraocular and intraocular muscles reach the eyeball through what? what are these nerves?

peripheral

Area that is further away from the occipital pole is what kind of vision?

corticopontine

As coming down through midbrain, these fibers would be on either side of the corticospinal and corticonuclear fibers

The region that was ventral gray matter of the spinal cord now houses cell bodies (i.e. motor neurons) for CN XI (accessory n.) The region of the spinal cord that was the dorsal horn now contains the spinal nucleus of the CN V (trigeminal n.)

At the spinomedullary transition (below the pyramidal decussation), how do the ventral gray matter and dorsal horn change?

tensor tympani muscle

Attached to malleus (bony ossicle) and keeps tympanic membrane from vibrating too hard, reducing volume

saccade down

Bilateral inferior rectus

saccade up

Bilateral superior rectus

Left homonymous hemianopia These come together at the R optic tract, so lesion would be at the optic tract

Both eyes, left visual fields lost what is this called? where would the lesion be?

lateral foramen (of luschka)

CN VII (fascial) & CN VIII (vestibulocochlear) emerge laterally at this level

lens

Clear, convex Inverts and reverses image

vestibulo-ocular reflex

Connects with abducens and oculomotor nucleus via interneurons so they are moving together

Crista ampullares (the ampulla at one end of the semicircular canal)

Contains peripheral afferents of the vestibular pseudounipolar neurons

occulomotor n. (CN III)

Emerges ventrally from the midbrain at the medial edge of each crus and passes through the interpeduncular fossa, coursing between the superior cerebellar and posterior cerebral arteries

Cortical Lesion w/ Sparing of Macular Vision Would be in the cuneus and lingual gyrus has macula sparing because there is overlap in blood supply at the occipital pole

Entire hemiretina, but sparing of the macula occurring what is this called? where would the lesion be? why would there be sparing?

homonymous Lesion would be in the optic nerve (entire retina of the right eye)

Entire right or left visual field is blank what is this called? where would the lesion be?

hyperopia

Flat cornea Light rays hit the retina before they come into focus Glasses magnify to help correct farsightedness?

oculomotor & trochlear

Extraocular nuclei in the midbrain

accessory optic system

Gives input to superior and medial nuclei, can compensate for visual orientation

vestibulo-ocular

Head is moving Vestibular labyrinth induced Vestibular nuclei connect with extraocular nuclei Move eye in equal and opposite directions

corticospinal tract would also lose corticobulbar fibers, corticonuclear fibers trying to go to nucleus ambiguus and motor nucleus of trigeminal and facial Resulting in paralysis throughout your body Have lost everything that allows for communication except for vertical eye movements (function from midbrain)

Hyperextension of the neck, brainstem gets pushed back -- tearing anterior aspect of the brainstem so a torn basilar pons → tearing of which tract? what would this result in?

anterior spinal a.

If begin to have many symptoms (ex: motor on one side, sensory on one side, hypoglossal on one side), which artery would you be suspicious of?

Oculomotor nerve lesion Light came in, stimulated the EW nucleus, but neurons are not going back out appropriately to cause constriction on that side ex: if lesion is on L oculomotor nerve: -light shown in R eye, no direct reflex but have consensual -light shown in L eye, have direct but don't have consensual

If shine light into one eye, get direct light reflex; but other side does not constrict at all (no consensual light reflex), what does this mean?

stereognosis

Images are lined up next to each other (w/ cells coming from alternate eyes) to allow for what?

iris

In front of the lens dilates and constricts - but does not change focus of image on retina changes the amount of light admitted to the eye

spinocerebellar tracts

Info coming from spinal cord and entering into cerebellum

share info with the other side (trapezoid body) more of it crosses and goes up to inferior colliculus, but some ipsilateral as well

Input of cochlear nerves come to synapse in the cochlear nuclei, how does it share info?

macula sparing

Larger area, entire area that includes the fovea is spared somewhat because the area is supplied by calcarine artery (PCA) as well as collateral branches of MCA

sclera

Lateral margin of the cornea is continuous with this

1. Loud sounds (sensitive to them) 2. Salivation 3. Ipsilateral taste

Lesion at the chorda tympani would affect what 3 things?

lesion of facial nerve at the styloidmastoid foramen

Lesion here would affect ipsilateral facial expression (forehead, maxillary, and mandibular muscles)

pterygopalatine ganglion (parasympathetic ganglion)

Lesion here would cause inability to produce tears

geniculate ganglion (ganglion of the facial nerve)

Lesion here would cause loss of all mm & sensory (but would spare tear production and some of the glands in the nose and palatine area)

lose part of each eye (nasal retina area)

Lesion in the middle of the optic chiasm would cause what?

Broca's area

Lesion in this area would cause expressive aphasia

vestibulocochlear and the facial nerve

Lesion putting pressure through the internal acoustic meatus would put pressure on what 2 nerves?

rods!

Main photoreceptor in peripheral retina: cones or rods?

2 nuclei receiving sensory info from trigeminal nerve: Spinal trigeminal nucleus (extends caudally) Mesencephalic nucleus (extends rostrally)

Main sensory nuclei (2) (receives somatosensory info from the face) which way do they extend?

trigeminal nerve

Marks the transition between the basilar pons to the middle cerebellar peduncle

tectobulbospinal

Orienting reflex that tells you that something is happening to your side (tract)?

superior cerebellar artery

besides the quadrigeminal a., what other artery may the trochlear nerve and inferior colliculus be receiving blood from? (overlap)

RAS

Modulatory or arousal - input to vestibular system for upregulation; little more concerned about situation where don't have multiple other inputs

lateral geniculate nucleus

Most of the visual information travels through optic system to this nucleus and then to visual cortex

presbyopia

Normal loss of near-focusing ability that happens with age (begins around 40 years of age) Trouble reading small print Lens is less elastic

superior salivatory nucleus

Parasympathetic -- supplies most of the salivary glands Up by abducens nucleus, but close to the facial nerve as exiting As it gets carried down, branches off before getting to geniculate ganglion

would lose entire facial expression on that side eye would be very dry because have lost innervation to lacrimal duct

Peripheral lesion of the facial nerve such as Bell's Palsy in facial canal would cause what symptoms?

at the midbrain

Portion of the 4th ventricle narrows down to the cerebral aqueduct where?

Edinger Westphal nucleus (traveling with oculomotor nerve) Controlling pupillary light reflex (synapse in ciliary ganglion and control amount of pupil constriction)

Pretectal nuclei project to and synapse in the.. what does this control?

trigeminal ganglion spinal trigeminal nucleus

Primary afferent fibers of CN V conveying pain and non-discriminative touch from the face have their cell bodies in what? BUT what do they synapse in?

optokinetic nystagmus

Scene is moving Eyes move to compensate for the apparent movement of visual scene (400 degrees/sec)

Parasympathetic system - Edinger-Westphal & ciliary ganglion

Sphincter pupillae & ciliary mm. are supplied by....

myopia

Steeper curved cornea The eye is round and larger so the image is formed in front of the retina

would lose muscle of facial expression on lower face (lip droop), BUT would be able to raise eyebrows and close eye because still have ipsilateral innervation of upper face

Supranuclear lesion (above pons where nucleus is, ex: internal capsule or midbrain) would cause what symptoms?

Sympathetic system - superior cervical ganglia

Tarsal & dilator pupillae mm. are supplied by...

facial, trigeminal

Taste coming from anterior ⅔ of tongue is ___________ n., but sensation is ____________ n. (interaction of 2 different nerves)

same side!

Turning towards the semicircular canal increases the excitation on which side?

optic nerve (CN II)

bipolar cells synapse on ganglion cells ganglion cells generate AP and become what?

posterior commissure

The midbrain-diencephalic boundary is formed by this

pars oralis pars interpolaris pars caudalis

The spinal trigeminal nucleus is further divided into what 3 parts from rostral to caudal?

Bitemporal hemianopia Would result from the severance of the nasal retinal connections Lesion would be in the middle of the optic chiasm

The temporal visual field is what is affected what is this called? where would the lesion be?

lower; upper

Upper visual field is projected to the __________ retina lower visual field projects to the ___________ retina

shade

Using perception of ________ to tell you where something is in space

retinal slip

Visual scene moves across retina as the head moves

weakness of ipsilateral trapezius and ipsilateral SCM

a LMN (lower motor neurons) lesion of the accessory nerve would cause what?

weakness of contralateral trapezius and ipsilateral SCM

a UMN (upper motor neurons) lesion of the accessory nerve would cause what?

opsin

a class of protein that, together with retinal, constitutes the photopigments tuned to wavelength

superior quadrantanopia Contralateral visual field, inferior retina = contralateral (R/L) superior quadrantanopia

a lesion in meyer's loop would cause what

contralateral (R/L) inferior quadrantanopia

a lesion in optic radiations would cause what

the lesion is going to be contralateral to origin/symptoms you would be experiencing all the way up the system loss of contralateral pain and temp

a lesion to the ALS would cause what symptoms?

Tela choroidea

a thin membrane arising from the cerebellum and draping down like a tent to the edges of the 4th ventricle

hyperemia

an excess of blood in the vessels supplying an organ

posterior perforated substance

another name for the interpeduncular cistern

sup. orbital fissure

abducens nerve exits the skull via which foramina?

exotropia

abducted eye

esotropia

adducted eye

medial rectus

adducts eye toward the nose

synapses in posterior horn, crosses in AWS (at or within a couple of segments of where it enters) then secondary neuron ascends in the anterolateral system (lateral funiculus)

after the ALS synapses in the posterior horn, what happens?

postcentral gyrus

after the medial lemniscus has synapsed with the VPL/VPM, where does it finally end up?

basal plate

alar or basal plate? --motor, anterior/medial

alar plate

alar or basal plate? --sensory, posterior/lateral

internal capsule

area of white matter between the thalamus and the globus pallidus part of basal nuclei

vestibulocollic (head-righting) reflex

as move baby to the side, their head will come back up -- head wants to remain upright

the fovea!

at occipital pole -- large cortical representation because have one-to-one connection with the cones (precise vision)

Wernicke's area

auditory association cortex interpretation (larger in dominant hemisphere) anterior aspect of the parietal lobe input from primary auditory, visual association, and somesthetic association cortices Reading and writing -- understanding of language

Blood supply → labyrinthine branch of the AICA (or sometimes the basilar artery)

blood supply of semicircular canals

pigment epithelium

back part of the retina before reaching the choroid produces glucose ions to feed the retina protects retina by absorbing excess light rids dead cells

blind spot have a blind spot in each eye

because there are no photoreceptors at the optic disc, what does this create?

choroid!

behind the retina (blood vessels, interstitium, connective tissue)

lateral foramen of luschka

beside the inferior cerebellar peduncle and dumps into the cerebellopontine cistern

superior brachium of the superior colliculus

brings visual information FROM lateral geniculate body of the diencephalon TO the superior colliculus (is integrating info that is visual, auditory, and somatosensory

facial colliculus

bumps on the side of the median sulcus

Central retinal artery occlusive disease Atherosclerosis (most common reason) HTN Most > 60 years old

most sudden and dramatic event that can cause blindness what is it related to?

Only active during acceleration, but stop firing if at constant velocity

describe acceleration vs. velocity in the otolith organs

unmyelinated until they exit the eye

describe myelination of optic nerve

Compare & compensate → one side communicates with other so that if there is lesion on one side, input can still go to the other side and helps to decipher stimulus

describe the contralateral vestibular commuication

Sensation is not a summation of several cones, one cone specific to color Bipolar neuron that synapses onto specific cone

describe the sensation of seeing colors

movement agnosia parietal

difficulty perceiving movement what lobe would be involved here

in toward nose (vergence), out for far vision (convergence)

disconjugate movements of the eye

median sulcus

divides the floor of rhomboid fossa into right and left

striola

dividing line between the hair cells that have kinocilium on side moving toward

pars interpolaris

division of the spinal trigeminal nucleus in the middle, hybrid of the 2

pars oralis

division of the spinal trigeminal nucleus most about crude touch from oral cavity

pars caudalis

division of the spinal trigeminal nucleus most focused on pain (and temperature) from head and neck

all information from the visual field seen by one eye

each optic nerve carries what information

Levator palpebrae superioris

elevates upper eyelid

CN VI, VII, VIII

emerge in a medial-lateral sequence along the pontomedullary junction

scala tympani

ends at the round window

jugular foramen

glossopharyngeal nerve exits the skull via which foramina?

greater petrosal n.

goes to the pterygopalatine ganglion (supplies salivation in area, nasal glands, lacrimal glands) and the submandibular ganglion (supplies submandibular and lingual salivary glands)

substantia gelatinosa

gray matter structure of the dorsal spinal cord primarily involved in the transmission and modulation of pain, temperature, and touch

reticular activating system

grouping of cells within the reticular formation which project to the thalamus and from there to many parts of the cerebral cortex Loose network of neurons that fills in between nuclei and tracts may be responsible for regulating sleep-wake cycles, and it subconsciously activates the cerebral cortex to focus our conscious attention

ciliary body

has smooth muscles that alter lens thickness (parasympathetic)

organ of corti

hearing receptor inside of the scala media; between the scala vestibuli and scala tympani

central herniation

herniation directly down the middle of the brain

uncal herniation

herniation down through tentorium

tonsillar herniation

herniation of the cerebellum down through foramen magnum

striate medullaris

horizontal nerve fibers, divide the floor of the 4th ventricle into rostral and caudal sections & is at the division between the medulla and the pons Straddles the vestibular area (on top of the vestibular nuclei

Located within the temporal bone (petrous part) Located posterior and lateral to the cochlea

how are the semicircular canals located relative to the cochlea? they are within what bone?

Located lateral to the sulcus limitans in the medulla and pons Located posterior and lateral from the solitary nucleus and tract

how are the vestibular nuclei located relative to the following: 1. sulcus limitans 2. solitary nucleus & tract

defects are described by the part you can't see except for an optic nerve lesion

how are visual field deficits described

Right visual field entirely in the L optic tract Left visual field entirely in the R optic tract

how do optic tracts relate to visual fields?

Rods converge 50:1 = low light detection (pulling in low light, especially in the periphery) Cones converge ~3:1 = better definition

how do rods converge with bipolar cells? cones?

Just go down to the brainstem, but supplying the motor nuclei of the head and neck follow same initial pathway as the corticospinal tract: -from precentral gyrus -through internal capsule -through midbrain crus cerebri -terminate on cranial nerve motor nuclei

how do the corticobulbar fibers run?

via the arcuate fasciculus

how does information project from Wernicke's area to Broca's area?

basilar membrane vibrates up and down at specific frequencies pushes hair cells against the tectorial membrane each part of the cochlea has specific frequencies that it is sensitive to; when it gets to place where it is sensitive it pushes it sufficiently to cause depolarization of the hair cells causes nerve to carry that info back

how does the organ of corti allow for hearing?

medulla: UE posterior, LE anterior transitions in the pons midbrain: UE more medial, LE more lateral

how does the orientation of the medial lemniscus change throughout the brainstem?

Tectospinal -- cervical spine (turn head to look at stimulus) Tectobulbar -- gaze centers (move eyes to look at stimulus) Tectopontine -- cerebellum (project to cerebellum from pontine nuclei

how does the superior colliculus help to direct attention? (3)

100-700 degrees/sec

how fast are saccadic eye movements?

30-100 degrees/sec to keep object on foveas

how fast are smooth pursuit eye movements? why?

Lesion in the MLF so the nuclei are not connected, then may have lag of the oculomotor (giving you double vision)

how may an MLF lesion affect the vestibulo-ocular reflex?

medial lemniscus

hugs the midline posterior to the pyramids with the tectospinal tract at the level of the medullary olives

hypoglossal canal

hypoglossal nerve exits the skull via which foramina?

If an optic tract is blocked, may have a reduced amount of input to the EW nuclei → resulting in both eyes getting a reduced amount (but not in full) No transmission of light via damaged optic tract Still transmits light through undamaged optic tract

if have relative afferent pupil defect, what does this mean?

night blindness can't see shades of grey

if have too few rods

ipsilateral to lesion (ipsilateral sensory loss) contralateral to the lesion (contralateral sensory loss)

if lesion is at or below the nucleus gracilis/cuneatus (in/below medulla) then symptoms would be... if has already crossed (above medulla), then symptoms would be...

color blindness

if missing certain color molecules in the cones

retinal detachment Can't see the part that has become detached, blind spot, flashes of light, floaters that drift through vitreous

if retina detaches from pigment epithelium, what is this called? what are the symptoms?

optic nerve lesion

if shine it in one eye and there was no constriction in that eye that would indicate....

symptoms would be contralateral to lesion loss of contralateral motor control

if there is a lesion in the corticospinal tract above pyramidal decussation (ex: midbrain) how would symptoms manifest?

symptoms would be ipsilateral to lesion loss of ipsilateral motor control

if there is a lesion in the corticospinal tract below pyramidal decussation (ex: lateral spinal cord) how would symptoms manifest?

inferior rectus

if they eye is abducted, which muscle points it down?

raphe nuclei

important cell groups in the reticular formation, clustered in the midline of the medulla, pons, and midbrain many of these neurons synthesize serotonin and give rise to bilateral spinal projections to have inhibitory action on nociceptive neurons in laminae I and II

intermediate reticular zone

in medulla, the autonomic zone of the reticular formation; assists in regulation of visceral, CV, and respiratory functions

accessory cuneate nucleus

in the caudal medulla, this carries information from UE that goes into the cerebellum via the inferior cerebellar peduncle

posterolateral

in the midbrain, the MLS moves laterally but maintains the same orientation as in the pons so that the fibers for the lower extremity (from the nucleus gracilis) that were ventral in the medulla are now oriented HOW to those from nucleus cuneatus?

object agnosia

inability to recognize objects

sulcus limitans

indentation dividing sensory nuclei from the motor nuclei

nucleus ambiguus

large group of motor neurons providing innervation to the muscles of the soft palate, larynx, and pharynx (CN IX, X, XI)

middle

largest, most lateral cerebellar peduncle, only carries pontocerebellar neurons

the abducens nucleus

lateral rectus m. is supplied by..

vagal

lateral trigone that covers motor nucleus of vagus nerve

area postrema

located along the caudal margins of the 4th ventricle and serves as a chemoreceptor that triggers vomiting if it detects a toxin in the CSF (medic center)

reticular formation (formed by the tegmentum)

located between the pons proper and the 4th ventricle the central core of the brainstem and mediates level of consciousness

reticular formation

located in the central part of the brainstem, these neurons have long dendrites that enable them to receive and integrate synaptic inputs from most of the systems contacting the brainstem

principal trigeminal sensory nucleus

located next to the motor nucleus carries info from all over the face discriminative touch other ganglions hang off of this that have nothing to do with it (ex: pterygopalatine ganglion, maxillary nerve of trigeminal)

to provide sensation to the face does NOT carry parasympathetic nerves

main function of the trigeminal nerve

inf. colliculus

major synaptic relay for auditory info

for the body -- Ventral posterolateral (VPL) nucleus for the head -- Ventral posteromedial (VPM) nucleus

medial lemniscus gets up to thalamus and synapses which what? head vs. body?

contralateral

medial lemniscus is (ipsilateral/contralateral) to its cell of origin in the medulla

hypoglossal trigone

medial, motor trigone

the oculomotor nucleus

medial, superior, inferior rectus, inferior oblique, levator palpebrae are supplied by

macula

middle at intersection of quadrants, wide area that has good vision

choroid

middle, vascular layer of the eye, between the retina and the sclera

the cerebellum

modulates the vestibular nuclei as compensation for imbalance, don't want to do it excessively (gives you input for this proprioception)

vergence Medial recti as move nearer Lateral recti as move further away

movements move the eyes in opposite directions (back together or out to focus on something in the distance) Head is not moving but the extraocular muscles must be simultaneously activated to both fovea on the target -- NOT conjugate (disconjugate or disjunctive)

superior rectus inferior rectus medial rectus inferior oblique

muscles of the eye innervated by CN III

lingual nerve

nerve coming from tongue and mucosa

alveolar nerve

nerve from teeth & lip

mandibular

nerve that carries input from lower lip, skin of mandible and chin, mandibular teeth, lining of the oral cavity, anterior ⅔ of the tongue, TMJ

ophthalmic

nerve that carries input from skin of forehead, cornea, eyelid, paranasal sinuses some proprioceptive input

maxillary

nerve that carries input from the upper lip, skin of maxilla, maxillary teeth, nasal mucosa, palate

oculomotor

nerve that exits ventrally from the interpeduncular space/fossa between the cerebral peduncles at the level of the superior colliculi

cochlear nuc

nuclei located in dorsolateral part of the medulla

vestibular nuc

nuclei located lateral to the sulcus limitans

2 vestibular nuclei (med/inf) 2 cochlear nuclei (ant/post)

nuclei that surround the inferior cerebellar peduncles

central

nucleus or pathways disrupted, causing hearing loss

during development (critical period - within first 2 years)

ocular dominance and stereognosis is most important when?

superior orbital fissure

oculomotor nerve exits the skull via which foramina?

cribriform plate

olfactory nerve exits the skull via which foramina?

homonymous

on same visual field side

otoconia

on top of the otolith membrane, giving it weight Stimulates hair cells by pulling the membrane with it during movement

olfactory

only CN that can regenerate

trigeminal mesencephalic nucleus

only case in the midbrain where you have the cell bodies of the sensory neuron within the CNS the rest have them out in the ganglia found on the side of the PAG

mesencephalic nucleus

only nucleus within brainstem that has primary cell bodies located within the CNS

cataract Replacement restores light but can't alter thickness, so can't adjust vision using plastic lens

opaque lens (cloudy)

optic canal

optic nerve exits the skull via which foramina?

dorsal horn (lamina VII and VIII)

origin of the somatosensory and viscerosensory information that reaches the reticular neurons (anterolateral reticular nucleus)

uncus

part of parahippocampal gyrus

intermediate nerve

part of the facial nerve that exits through the internal acoustic meatus

lateral reticular nucleus

part of the reticular formation that projects to the cerebellum

diplopia

perception of 2 images of the same object direction of double vision depends on the visual axes, this is the functional result of the 2 visual axes

monocular area

peripheral area seen by one eye

rods and cones

photoreceptors

substantia nigra

pigmented nucleus found in the midbrain that contain dopamine and communicate with basal nuclei separating the 2 regions of the cerebral peduncles

loss of vision in that eye

pressure on optic nerve would cause what?

rostral solitary nucleus

processing info of taste from anterior ⅔ of tongue (sensory part of facial nerve) cell body located in the geniculate ganglion and ends here

in the trigeminal motor nucleus

proprioceptive information from the mandibular nerve comes in, loops down to motor neurons in what nucleus for feedback loop?

principal nucleus of the thalamus

provides information about sensation on your face and head that is then added into medial lemniscus

stapes

pushes the oval window on the cochlea -- starts a wave in the perilymph in scala vestibuli to the apex, through the helicotrema (opening between scala vestibuli and scala tympani) and then down again through the scala tympani

dorsal (magnocellular) pathways?

visual association cortex that is located in the parietal lobe tells you where the object is and where the object is moving (up/down, L/R)

Saccadic

rapid eye movement for finding a new target Head is still Eyes scan to new position (no object) refocus at new position voluntary

At level of the olives (rostral), central canal has expanded into 4th ventricle

region of the open medulla

lateral reticular region

regions of reticular activating system (RAS) in the cerebellum that function to make the cerebellum more active and fine tuned to react quickly

Gigantocellular reticular region

regions of reticular activating system (RAS) in the medulla that receives information from the ALS and is respondible for HR and respiratory function

saccular maculae

respond to up and down movement (acceleration)

inferior olivary nucleus

responsible for external expansion of the olives

maculae gravity - pulling down on hair cells

responsible for linear accelerations OR gravity of the otolith organs how does gravity affect it?

cones

retinal cells, receptors for color Specialized for red, green, and blue -- very discriminatory

rods

retinal cells, receptors for light diffuse -- poor discrimination

Anterior medullary velum and the cerebellum

roof of the 4th ventricle

posterior ciliary artery

runs in the choroid that is surrounding the retina, providing it with nutrients

lateral (slightly tilted anterodorsal

semicircular canal that is horizontal to the petrosal ridge

posterior

semicircular canal that is parallel to the petrosal ridge

anterior

semicircular canal that is perpendicular to the petrosal ridge

retrolenticular

sends information straight back from the superior retina

corneal reflex

sensation of eyeball is from trigeminal nerve, but synapses with facial motor nucleus to cause closing of the eye would be unable to close eye when putting something close to eye would indicate peripheral lesion

semicircular canals

senses angular (rotational acceleration)

otolith organs (utricle, saccule)

senses linear acceleration

the spinal trigeminal nucleus

sensory for the skin of the external acoustic meatus cell body in the geniculate ganglion, comes down to here

maculae

sensory organs of otolith organs

basilar membrane

separates the scala tympani from the scala media

solitary nucleus

series of sensory nuclei; receives taste afferents from the facial (VII), glossopharyngeal (IX), and vagus (X) Longer nucleus that extends from the medulla up into the pons

interneurons

sharpen the edges of images mostly by inhibition

Cochlear and vestibular nuclei

sit dorsolaterally from inferior pons to superior medulla

superior brachium superior colliculus pretectal nuclei

small bundle of neurons bypass the LGN and branch through the _____________ _____________ to terminate on the _____________ _____________ (w/ some also projecting on the _____________ nuclei

fovea

small depression in middle of macula; where the best visual discrimination is seen

spinovestibular

small fibers/tract close to posterior spinocerebellar tract comes up to give proprioception to vestibular nuclei so that you know where you are

spinoreticular fibers (AL/ST) and spinal cranial nerves heart rate and respiration, pressure can cause apnea

somatosensory and viscerosensory information reaches the reticular neurons (anterolateral reticular nucleus) via WHAT? these cells are important in the control of what? what would happen if pressure affected this area?

anopia

something missing in visual field

the jugular foramen

spinal accessory nerve exits the skull via which foramina?

cerebral peduncle (crus cerebri)

stalk of nervous tissue connecting the cerebral cortex to the brainstem, spinal cord, and the pons nuclei

the trochlear nucleus

superior oblique m. is supplied by...

Edinger Westphal

supplies preganglionic neurons to control constriction of the pupil (pupillary light reflex) located next to the oculomotor nucleus and travel with the CN III -- anteriorly out of the interpeduncular fossa on the front side of the cavernous sinus and then superior orbital fissure Preganglionic neuron then synapses on the ciliary ganglion -- then have the postganglionic neurons going to the sphincter pupillae and the ciliary muscles

Superior salivatory nucleus

supplying the salivary nuclei of the mouth

retina

surrounds the back of the eye

crosses immediately, goes up into the pons, crosses again and comes back to the same side in the cerebellum enter through the SCP and then goes back to the same side

the anterior spinocerebellar tract ascends in the spinal cord in what area? when and where does it cross? how does it enter the cerebellum?

flexible, low

the apex of the cochlea is more (flexible/stiff) allows for reception of (low/high) tones

binocular zone

the area that both the R & L eye see together

stiff, high stiffens with age

the base of the cochlea is more (flexible/stiff) allows for reception of (low/high) tones

Choroid epithelium (pigment epithelium)

the base of the retina → where cones and rods are sticking into it

temporal retina

the binocular zone is the area projected to and seen by the .....

visual field

the central and peripheral areas seen by that one eye (R/L)

gray matter outer portion contains white matter

the central portion of the medulla at the level of pyramidal decussation contains

from the thalamus to the upper thoracic spinal cord

the descending sympathetic pathway has to travel where?

Anterior inferior cerebellar artery (AICA) May also receive some from the PICA

the dorsal and ventral cochlear nuclei are supplied by which artery?

Not formed by the facial nucleus, formed by the abducens nucleus BUT facial nerve comes up and around the abducens nucleus before it exits from the pontomedullary junction (branchial motor intervention)

the facial colliculus are formed by which nuclei?

facial motor nucleus

the facial nerve carries motor neurons from the what nucleus?

in the internal genu of the facial canal, lateral to where greater petrosal nerve comes off, but before tympanic cavity

the geniculate ganglion is located where?

visual agnosia

the inability to recognize a visual stimulus despite the ability to see and describe it

nasal retina

the monocular zone is the area projected to and seen by the .....

trochlear (CN IV)

the only cranial nerve that emerges from the posterior brainstem

infundibular stalk and pituitary gland

the optic n. is rostral to what?

the facial nucleus

the orbicularis oculi m. is supplied by

strabismus

the physical misalignment of the eyes

obex

the point at which the 4th ventricle narrows to become the central canal of the spinal cord decussation of sensory fibers happens at this point

middle cerebellar peduncles

the pontine nuclei cross midline forming this on their way to the cerebellum

lateral funiculus remains uncrossed and centers into the cerebellum ICP

the posterior spinocerebellar tract ascends in the spinal cord in what area? when and where does it cross? how does it enter the cerebellum?

Pain, temperature, crude touch

the spinal trigeminal nucleus senses what?

quadrigeminal cistern

the subarachnoid space immediately dorsal to the colliculi

interpeduncular cistern

the subarachnoid space of the interpeduncular fossa Contains oculomotor n. (CN III) and the upper part of the basilar artery

tectospinal tract

the superior colliculus initiates what tract?

Sound -- inf. colliculus Visual -- through brachium of superior colliculus from thalamus Touch -- info comes up medial lemniscus, contributing information to superior colliculus

the tectobulbospinal tract integrates what kind of info? from where?

Vestibulo-ocular reflex Optokinetic response

these 2 reflex eye movements stabilize the eye while the head moves

Postganglionic neurons

these control sphincter pupillae muscles of iris for constriction in bright light

Superior & inferior rectus

these muscles move eye up and down when it is abducted

inferior oblique - moves eye up superior oblique - moves eye down

these muscles move eye up and down when it is adducted

ultricular maculae

these respond to the acceleration of the head or movement to the side or forward/back

conjuctiva

thin lining over cornea

anterior medullary velum

thin membrane holding in CSF and covers rostral part of pons

EW

this nucleus sends parasympathetic preganglionic neurons with the oculomotor nerve to synapse in parasympathetic ciliary ganglion

Cerebellar tonsils Medullary reticular formation (control of HR, breathing)

tonsillar herniation would affect what things?

post. trigeminothalamic tract

tract of the spinal trigeminal nucleus travels ipsilateral; carries oral mucosa sensation

ant. trigeminothalamic tract

tract of the spinal trigeminal nucleus travels with the medial lemniscus and terminates in ventral posteromedial (VPM) thalamus once it comes in through the spinal trigeminal or chief sensory, crosses and travels with the medial lemniscus goes up to sensory cortex that is most lateral VPL → UE, LE, and trunk

corticobulbar (nuclear)

tract that innervates CNS of brainstem

optic tract

travels anterolateral to the cerebral peduncles (around ambient cistern) and terminates in the lateral geniculate nucleus (LGN)

V1 - superior orbital fissure V2 - foramen rotundum V3 - formanen ovale (all motor neurons exit through the foramen ovale since muscles that they are going to are going to the mandible)

trigeminal nerve exits the skull via which foramina? (3 parts)

superior orbital fissure (SOF)

trochlear nerve exits the skull via which foramina?

prosopangnosia occipitotemporal cortex (fusiform gyrus)

unable to recognize people by looking at the face what would be involved in this

CN III corticospinal tract

uncal herniation would affect what things?

jugular foramen (JF)

vagus nerve exits the skull via which foramina?

superior and medial

vestibular ganglia mainly input from semicircular canals and saccule important to have this info and match it up with the eye movement

medial, lateral, and inferior

vestibular ganglia receiving input primarily otolith organs some semicircular canal pairs also giving information encode both angular and linear components of head movement (balance)

scarpa's

vestibular ganglion

vestibulo-ocular reflex!

vestibular system is telling the head which direction you are moving and the eyes move in equal and opposite directions

internal acoustic meatus (IAM)

vestibulocochlear nerve exits the skull via which foramina?

Inferior and superior cerebellar peduncles

walls of the 4th ventricle

CN III (oculomotor) CN IV (trochlear)

what 2 cranial nerves are associated with the midbrain?

the crossing of the pontocerebellar fibers

what allows you to ID x-sections of the pons

One end is getting info about proprioception, the other end is going to the motor nucleus of the trigeminal

what are the 2 routes of the trigeminal mesencephalic nucleus?

anterior trigeminothalamic tract posterior trigeminothalamic tract

what are the 2 tracts of the spinal trigeminal nucleus?

mesencephalic nucleus principal trigeminal sensory nucleus spinal trigeminal nucleus

what are the 3 parts of the sensory trigeminal nucleus from rostral to caudal?

V1 - ophthalmic V2 - maxillary V3 - mandibular

what are the 3 trigeminal divisions?

1. Temporal branch → frontalis, orbicularis oculi 2. Zygomatic branch → zygomaticus 3. Buccal → orbicularis oris, buccinator 4. Marginal mandibular → chin area, platysma 5. Cervical → platysma

what are the 5 branches of the facial nerve that emerges from the styloidmastoid foramen and what do they innervate?

Afferent (sensory) - trigeminal n., senses the cornea Efferent (motor) - facial n., orbicularis oculi

what are the afferents and efferents of the blink reflex?

AICA (anterior inferior cerebellar artery) PICA (posterior inferior cerebellar artery) ASA (anterior spinal artery) PSA (posterior spinal artery)

what are the arteries that supply the medulla? (4)

basilar artery (paramedian pontine branches) pontocerebellar angle lesion

what are the arteries that supply the pons? (2)

Pineal gland Inferior/superior colliculi

what are the borders of the superior (quadrigeminal) cistern

Glossopharyngeal (CN IX) Vagus (CN X) Accessory (CN XI) Hypoglossal (CN XII)

what are the cranial nerves associated with the medulla?

CN V (trigeminal) CN VI (abducens) CN VII (facial) CN VIII (vestibulocochlear)

what are the cranial nerves associated with the pons? (4)

lateral vestibulospinal tract medial vestibulospinal (travels in the MLF)

what are the descending efferents of the vestibulocochlear system?

CN V (spinal trigeminal) -- motor nucleus and tracts CN XI (accessory) -- exits through anterolateral sulcus

what are the motor neuron groups of the caudal medulla

smooth muscles situated in both eyelids Travel with CN III & V Function -- open eyelid Superior tarsal muscle → superior eyelid, sympathetic postganglionic n. Purpose of this is to make sure that you have as much light as you can and see as much as possible Would still be able to open your eye part way because of this if have some sort of oculomotor palsy

what are the tarsal muscles innervated by? what does it do?

Parasympathetic - craniosacral Sympathetic - thoracolumbar

what areas of the spinal cord relate to the parasympathetic nervous system? sympathetic?

Temporal retina of each eye hugs their respective sides of optic chiasm Nasal retina crosses in the chiasm

what do the temporal and nasal retina do in the optic chiasm

Goes through the optic canal with the optic nerve

what does the central retinal artery travel with? through what?

comprises medial/lateral vestibulospinal tracts, influences muscle tone for balance and posture

what does the descending portion of the medial longitudinal fasciculus do? what tracts does it include?

Trochlear nerves (exiting) Great cerebral vein Distal branches of the posterior cerebral arteries

what does the quadrigeminal cistern contain?

sphincter pupillae & ciliary muscle

what eye muscles are affected by the parasympathetic system?

pupillary dilator & tarsal muscles

what eye muscles are affected by the sympathetic system?

This contains fibers from CN V (trigeminal), CN IX (glossopharyngeal), & CN X (vagus) Carries sensory information about crude touch, pain, and temperature from the ipsilateral face

what fibers does the spinal trigeminal nucleus carry? what kind of info does this carry?

motor SCM, trapezius → turns the head

what function does the spinal accessory nerve have?

contralateral (R/L) homonymous hemianopia both eyes are working, but only see the R or L side of each eye

what happens if optic tract is interrupted?

If the intracerebral pressure (ICP) increases (ex: hemorrhage, too much CSF) → pushes forward optic disc and becomes blurred, difficult to see

what happens to the optic disc if intracerebral pressure increases?

Occurs with a constricted pupil due to a loss of sympathetics to the eye

what happens to the pupil with ptosis caused by Horner's syndrome?

Occurs with a dilated pupil due to a loss of innervation to the sphincter pupillae

what happens to the pupil with ptosis caused by lesion to the oculomotor n.?

rate goes down

what happens to the rate when bend away from the kinocilium?

rate goes up

what happens to the rate when bend torward the kinocilium?

Won't be deaf if have accident that injures the temporal lobe, but may have some hearing loss A rostral lesion would especially affect more of the low frequencies

what hearing loss would be present from injury to temporal lobe?

visual processing, multisensory reflex processing The most superficial layers are dedicated to vision The deeper layers integrate information from vision, hearing, and somatosensory to alert the brain to pay attention to the stimulus

what is the function of the superior colliculi? superficial layers? deeper layers?

Important to parasympathetic visceromotor & sensory functions -roams all over the internal part of the body -sensory component deals with regulation of BP and pH of blood

what is the function of the vagus nerve?

CN 3 and 4 - eye movement Contralateral UE movement Contralateral discriminative touch

what is the functional loss from a lesion in the PCA? (3)

contralateral paralysis contralateral discriminative touch double vision - ipsilateral (lateral rectus paralysis)

what is the functional loss from a lesion in the paramedian pontin branches of the basilar a.? (3)

proprioception of the face (mesencephalic) contralateral pain and temp (ALS) contralateral discriminative touch from LE (medial lemniscus) subtle eye movement - may have diplopia (trochlear nerve) partial hearing (lateral lemniscus

what is the functional loss from a lesion in the quadrigeminal a.? (3)

ipsilateral hearing loss some loss of balance - lose info coming into cerebellum about balance

what is the functional loss from a lesion to the AICA? (2)

contralateral paralysis (motor control) ipsilateral tongue movement (tongue points tot he side of the lesion) contralateral discriminative touch

what is the functional loss from a lesion to the ASA? (3)

wallenburg's syndrome/lateral medullary syndrome (acute ischemic infarct of the lateral medulla) contralateral loss of pain sensation from the body (info not getting to cortex) ipsilateral loss of pain sensation from the face some loss of balance loss of taste (rostral solitary nucleus) BP imbalance (caudal solitary nucleus) hoarseness and dysphagia

what is the functional loss from a lesion to the PICA? (7)

ipsilateral UE and LE discriminative touch ipsilateral face pain & temp

what is the functional loss from a lesion to the PSA? (3)

ipsilateral loss of pain/temperature to the face AND ipsilateral loss of mastication (trigeminal) contralateral body pain & temp loss of facial motor (ipsilateral side of face sags)

what is the functional loss from pontocerebellar angle lesion? (3)

1. reflex control of CV and respiratory systems 2. reflex control of swallowing and vomiting 3. important in phonation (control of tongue, larynx, and pharynx)

what is the functional significance of the medulla? (3)

1. coordinate eye movements 2. pupillary light reflex 3. consciousness and arousal (reticular formation)

what is the functional significance of the midbrain? (3)

1. Reflex control of respiratory system 2. Eye movement, coordinated movement of the eyes and head 3. Corneal reflex

what is the functional significance of the pons? (3)

ascends in dorsal columns (fasciculus gracilis/cuneatus)

what is the location of the medial lemniscal system?

Mostly from the posterior cerebral artery -- calcarine branch Laterally -- MCA... small overlap here between MCA and PCA

what is the main blood supply of the primary visual cortex?

Patient complaint of diplopia when looking to the left (abducting - lateral rectus) 2 different pictures (one looking straight ahead and one to the left)

what is the main symptom of abducens palsy?

Patient complains of vertical diplopia → when looking up or down seeing 2 different images

what is the major complaint with trochlear nerve palsy?

peripheral sensory receptors dorsal root ganglion, synapse in posterior horn

what is the origin of the ALS?

primary motor cortex (precentral gyrus)

what is the origin of the corticobulbar fibers?

primary motor cortex (precentral gyrus) LE -- close to the longitudinal fissure UE, head, & neck -- more lateral

what is the origin of the corticospinal tract? UE vs. LE?

sensory receptors (ex: end of fingers) primary cell body of the pseudounipolar neuron in the DRG (primary neuron doesn't synapse in the spinal cord, just brings info up dorsal column)

what is the origin of the medial lemniscal system?

comes from cortex, through the internal capsule Goes through midbrain crus cerebri, basilar pons, then becomes medullary pyramid Cross in the pyramidal decussation to become the lateral corticospinal tract in the spinal cord Location of tract → lateral corticospinal tract

what is the path taken by the corticospinal tract?

1. internal acoustic meatus 2. facial canal 3. greater petrosal n. 4. genu 5. chorda tympani 6. styloidmastoid foramen

what is the path taken by the facial nerve upon exiting the skull?

Travel with CN V Function -- increase light

what is the pupillary dilator muscle innervated by? what does it do?

this receives input primarily from the cerebral cortex (motor cortex) and projects to the contralateral cerebellum important when learning something new

what is the purpose of the inferior olivary nucleus that is contained in the olives of the medulla?

90

what is the resting constant firing of the kinocilium

in the trigeminal ganglion

what is the somatosensory nucleus associated with the maxillary nerve?

Innervated by CN III (EW) Function -- reduce light, narrows the opening of the pupil

what is the sphincter pupillae muscle innervated by? what does it do?

Change the lens curvature (focusing on different places) Pupil diameter changes

what is vergence coupled with?

rostral interstitial nucleus of the MLF

what is vertical eye movement managed by?

Horner's syndrome

what may be a result of injury to the descending sympathetic pathway

Has preganglionic cell body, but starts in the intermediolateral cell column of the spinal cord (between the dorsal and ventral horn) Comes out and goes up to the superior cervical ganglion to get to the postganglionic cell body Main thing you want to be able to do is dilate the pupil (dilator pupillae) Using it if in low light, excited, or have had too much coffee might be using the dilator pupillae

when and what is used by the sympathetic system in the eye

ptosis

when the upper eyelid droops over the eye

macula and fovea

where are more cones found?

on the cuneus

where do optic radiations terminate?

in the VPL or VPM of the thalamus finally synapse in the postcentral gyrus

where does the ALS terminate?

comes straight down and exits at the pontomedullary junction, close to the midline

where does the abducens nerve exit the brainstem

closest to midline @ pontomedullary junction

where does the abducens nerve originate?

fibers loop around abducens nucleus before exiting brainstem on ventrolateral surface of the caudal pons (near pontomedullary junction)

where does the facial nerve exit the brainstem

more medial, between the olive and inferior cerebellar peduncle @ lateral foramen

where does the facial nerve originate?

rostral, in the sulcus dorsal to the olive (ventrolateral sulcus)

where does the glossopharyngeal nerve originate?

anteriorly, between the olive and the pyramid (rostral medulla)

where does the hypoglossal nerve exit from the brainstem?

b/t the olive and pyramid

where does the hypoglossal nerve originate?

b/t cerebral peduncles (interpeduncular cistern)

where does the oculomotor nerve originate?

to visual association cortex

where does the primary visual cortex project?

caudal, in the sulcus dorsal to the olive (ventrolateral sulcus)

where does the spinal accessory nerve originate?

crosses immediately in midbrain and remains medial descends to cervical spinal cord to turn head to stimulus tectobulbo portion of the tract → goes down to the reticular formation to up-regulate (activating it a bit more)

where does the tectobulbospinal tract run?

at pontocerebellar angle (into the middle cranial fossa)

where does the trigeminal nerve exit the brainstem

b/t basilar pons and middle cerebellar peduncle

where does the trigeminal nerve originate?

caudal to inferior colliculi (ambient cistern)

where does the trochlear nerve originate?

middle, in the sulcus dorsal to the olive (ventrolateral sulcus)

where does the vagus nerve originate?

more lateral, between the olive and inferior cerebellar peduncle @ lateral foramen

where does the vestibulocochlear nerve originate?

in the facial canal

where is scarpa's ganglion located?

anterior temporal lobe periamygdaloid cortex and piriform cortex alongside the ambient cistern amygdala is in the anterior part of the temporal lobe (vulnerable)

where is the primary olfactory cortex located?

orbitofrontal cortex Integrate to create flavor -input to the hypothalamus -- tell you about feeding -input to the hippocampus (to entorhinal cortex) -- experience of what you're eating

where is the secondary olfactory cortex? what is its purpose? what does it communicate with? (2)

on anterior horn motor neuron that will then go out to the body

where is the termination of the corticospinal tract?

continues until it synapses in the nucleus cuneatus or nucleus gracilis (medulla)

where is the termination of the medial lemniscal system?

medial

where is the trigeminal motor nucleus relative to the chief sensory nucleus of the trigeminal?

optic chiasm

where the optic nerves converge

styloid mastoid foramen

where the rest of the facial nerve emerges from the skull, divides into 5 branches, and innervates the muscles of facial expression

the ambient cistern, anterolateral to the crus cerebri

which cistern is the optic tract in?

bilaterally on CN V, VII, and nucleus ambiguus crossed: CN VII (lower face) & most of XII -- some that go to both sides but primarily crossed

which cranial nerve motor nuclei do the corticobulbar fibers terminate on?

CN III, IV, & VI Allows conjugate eye movement to be coordinated with head movement

which cranial nerves do the vestibular nuclei project to? why?

rods outnumber cones by 20:1

which is more abundant, rods or cones?

medial vestibular nucleus

which main nucleus is connecting with abducens and oculomotor so they move together

lateral rectus

which muscle of the eye does the abducens innervate?

CN V, VII, IX, and X (primarily V)

which nerves does the spinal trigeminal nucleus receive input from?

CN IX (glossopharyngeal) CN X (vagus) CN XI (spinal accessory)

which nerves emerge from the postolivary sulcus

abducens

which nuclei are associated with the abducens nerve?

spinoreticular Lesion here would cause drop in HR and respiratory rate and could be fatal

while ALS is traveling to the thalamus, some fibers stop in the medulla and branch to synapse with reticular formation (HR, respiratory function)

Squinting helps to see better because you are limiting the number of receptors that are being stimulated

why does squinting help to see better

no activation of sweat glands

why may anhidrosis occur?

no dilator

why may miosis (pupil constriction) occur?

no tarsal

why may ptosis occur?

Receives bilateral input from both sides of cortex → so won't fully lose muscles of mastication if have a stroke because still have ipsilateral innervation

will you lose full function to muscles of mastication if you have a stroke?

the fovea

would see the best part, right in the middle of the binocular zone