Brainstem

Front 1

Q

Back 1

A

Hint 1

note

Front 2

What does the superior and inferior colliculus do?
Where are they located?

Back 2

Dorsal, rostral surface of brainstem
Separated from midbrain by cerebral aqueduct
Function: SC--> eye movements,visual attention; IC--> auditroy processing

Hint 2

081613_FM201_L_Brainstem101

Front 3

CST travels in what part of the brainstem? What other tract travels with it?

Back 3

Medulla and pons: Splits at the 2 cerebral peduncles,then comes together at ventral medial surface at pons
Course: From cerebral peduncles --> base of pons --> Medullary pyramids
CBT (corticobulbar tract) travels with the CST from motor cortex --> synapses at the appropriate CN motor nuclei along its course in the brainstem (no oculomotor)

Hint 3

081613_FM201_L_Brainstem101

Front 4

What are the cerebellar circuitry in the brainstem?
Location of these brainstem nuclei containing cerebellar circuitry?

Back 4

Medulla: Inferior olive (rostral medulla) --> laterally located, dorsal to CST
Pons: Pontine nuclei/griseum pontis
Midbrain: Red nucleus
* All 3 are located VENTRALLY in brainstem and have connections to cerebellum via cerebellar peduncles

Hint 4

081613_FM201_L_Brainstem101

Front 5

How does the cerebellar circuitry in the brainstem get to the cerebellum? Location?

Back 5

CEREBELLAR PEDUNCLES: axons traveling to and from cerebellum
Medulla: Inferior olive --> ICP: dorsal section
Pons: Pontine nuclei --> MCP: dorsal section
Midbrain: Red nuclei --> SCP: dorsal section but double

Hint 5

081613_FM201_L_Brainstem101

Front 6

Testing cerebellar function

Back 6

Tandem gait, heel-shin, nose to finger, coordinate rhythm of rapid, alternatingmovements

Hint 6

081613_FM201_L_Brainstem101

Front 7

What axons/tract forms the inferocerebellar peduncle?

Back 7

Dorsal spinocerebellar-joint/limb position from lower limb
Cuneocerebellar- joint/limb position of upper limb

Hint 7

081613_FM201_L_Brainstem101

Front 8

When do you see the cerebral peduncle in a myelin section first? What region?

Back 8

Midbrain --> split in too
Lots of white matter --> CST, CBT, CPT

Hint 8

081613_FM201_L_Brainstem101

Front 9

What cranial nerves are attached near midline of brainstem? What CN to what region

Back 9

3-medial midbrain
4- pons-midbrain jnctn (but dorsal exit)
6-medial pons-medulla jnctn
12- medial medulla

Hint 9

081613_FM201_L_Brainstem101

Front 10

What CNs are attached to pons? What CN to what region of pons?

Back 10

5- (lateral) midpons
6 (medial),7-8 (lateral)- ponto-medullary jnctn

Hint 10

081613_FM201_L_Brainstem101

Front 11

What CNs are attached to medulla? What CN to what region?

Back 11

9-10-lateral medulla
12-medial medulla

Hint 11

081613_FM201_L_Brainstem101

Front 12

What is the only CN attached to the dorsal brainstem? What else is special about this?

Back 12

CN4- trochlear- only CN where motor neurons leaving the brainstem go to CONTRALATERAL side on exit

Hint 12

081613_FM201_L_Brainstem101

Front 13

Where is the motor and sensory nuclei located in brainstem?

Back 13

Motor- medial dorsal
Sensory- lateral, even more dorsal

Hint 13

081613_FM201_L_Brainstem101

Front 14

Sensory nuclei in the brainstem receive info from where?

Back 14

Cranial nerves

Hint 14

081613_FM201_L_Brainstem101

Front 15

Difference between somatic and branchial motor nuclei?
FUNCTION/LOCATION in the brainstem

Back 15

Somatic- 3,4, 6,12 --> move extraocular muscles and tongue; NUCLEI medial
Branchial- 5,7,9,10 --> move muscles of mastication, facial expression, pharynx, larynx; NUCLEI more LATERAL, VENTRAL

Hint 15

081613_FM201_L_Brainstem101

Front 16

Is there a motor nucleus at every transverse section we cut of the brainstem?

Back 16

No, the motor nuclei are interrupted

Hint 16

081613_FM201_L_Brainstem101

Front 17

What is the UMN tract of the brainstem (not corticospinal)?
What tract gives information to the motor nuclei of the cranial nerves?

Back 17

CorticoBULBAR tract (provide all motor info EXCEPT EXTRAOCULAR--> no CB tract to CN3,4,6)

Hint 17

081613_FM201_L_Brainstem101

Front 18

What is the blood supply to the BRAINSTEM? Does a stroke take out all regions?

Back 18

Vertebro-basilar system
VERTEBRAL, Ant spinal, PICA: to CAUDAL and ROSTRAL MEDULLA
BASILAR, AICA: to CAUDAL PONS
BASILAR, pontine, SCA: to MID, ROSTRAL PONS
BASILAR, PCA: to MIDBRAIN (PCA is lateral)
Stroke could take out medial and spare lateral:
MEDIAL- PARAMEDIAN PENETRATING
LATERAL- CIRCUMFERENTIAL PENETRATING

Hint 18

081613_FM201_L_Brainstem101

Front 19

What is the function of the reticular formation?
Where is it in the brainstem?
What happens if you lesion here?

Back 19

Reticular formation- central core of brain stem (nuclei and axons)
Function at MIDBRAIN: consciousness --> Lesion= not fatal
Function at MEDULLA: VITALS (respiration, HR control)-->lesion=death

Hint 19

081613_FM201_L_Brainstem101

Front 20

UMN and LMN saga continues in the brainstem for CN
T or F

Back 20

tRUE -->same sx

Hint 20

081613_FM201_L_Brainstem101

Front 21

If the tongue deviates to the left --> is the lesion ipsilateral or contralateral?

Back 21

Ipsilateral LMN issue

Hint 21

081613_FM201_L_Brainstem101

Front 22

Why might one have CN3,4,6,12 motor sx (eye/tongue) and bodily motor sx too (neck down)?

Back 22

Medialy located CN motor nuclei (3,6,12) send axons ventrally and medially -->traveling very close (lateral) to CST
A medial brainstem stroke could take out both of these MOTOR tracts

Hint 22

081613_FM201_L_Brainstem101

Front 23

CN3 palsy may cause what else other than vision problems?

Back 23

CN3 controls many extraocular muscles AND LPS (OPENS EYELID) --> full ptosis (not half like Horners)
PSNS fibers travel on CN3 fibers --> PSNS lesion= blown pupil

Hint 23

081613_FM201_L_Brainstem101

Front 24

Why does pain from middle ear, pharyn, larynx feel sharp and well localized (like somatic pain)

Back 24

Pain fibers from CN7,9,10 join the spinal5tract and get processed at spinal5 nucleus as if they were somatic sensation

Hint 24

081913_FM201_L_Brainstem2-Trigeminal

Front 25

What part of the brainstem do you find motor nuclei?

Back 25

Medial- near the midline

Hint 25

081913_FM201_L_Brainstem2-Trigeminal

Front 26

When motor neurons leave the brainstem, are they going to the same side or opposite?

Back 26

All cranial motor neurons leaving the brainstem go to IPSILATERAL skeletal muscle EXCEPT TROCHLEAR (CN4)

Front 27

What part of the brainstem do you find sensory nuclei?

Back 27

Lateral, dorsal
Some are more distinct, some run throughout the brainstem (CN5)

Hint 27

081913_FM201_L_Brainstem2-Trigeminal

Front 28

When sensory info from sensory ganglion cells of cranial nerves enter the brainstem- are they crossed or uncrossed?

Back 28

UNCROSSED- all the sensory ganglion will also synapse in the IPSILATERAL side of the brainstem

Hint 28

081913_FM201_L_Brainstem2-Trigeminal

Front 29

What are the 3 sensory nuclei in brainstem and what CNs provide info to each?

Back 29

. Somatic sensory: CN 5,7,9,10 -->all of face, inside nose, mouth, eye, until middle ear, pharynx,larynx
. Visceral sensory: taste (CN 7, 9,10) inputs from viscera for cardiac, resp, dig fnctns: NUCLEUS SOLITARIUS
. Vestibulocochlear: CN8

Hint 29

081913_FM201_L_Brainstem2-Trigeminal

Front 30

What is the visceral sensory nuclei in the brainstem?

Back 30

Visceral sensory: taste (CN 7, 9,10) inputs from viscera for cardiac, resp, dig fnctns: NUCLEUS SOLITARIUS

Hint 30

081913_FM201_L_Brainstem2-Trigeminal

Front 31

Where are the preganglionic parasympathetic neurons/axons in the brianstem?

Back 31

No distinct nucleus --> scattered between branchial and somatic motor nuclei
More often located in the RETICULAR FORMATION

Hint 31

081913_FM201_L_Brainstem2-Trigeminal

Front 32

Why is there only PSNS nuclei in the brainstem- where is the SNS?

Back 32

Preganglionic sympathetic cell bodies (SNS) are in interomediolateral columns IN THORACIC SC
PSNS output is craniosacral!

Hint 32

081913_FM201_L_Brainstem2-Trigeminal

Front 33

What is trigeminal neuralgia? Why does it happen?

Back 33

Trigeminal neuralgia: pain in the V2,V3 region
Etiology: unknown

Hint 33

081913_FM201_L_Brainstem2-Trigeminal

Front 34

pain and temperature loss on one side of face but opposite side of body?

Back 34

brainstem lesion is SAME side as the facial sensory loss,
between CAUDAL MEDULLA and mid-pons
STT CROSSES AT ANTERIOR WHITE COMMISSURE IN SC (crossed already)
between MID-PONS and CAUDAL MEDULLA, is the IPSILATERAL SPINAL5TRACT (not crossed yet)

Hint 34

081913_FM201_L_Brainstem2-Trigeminal

Front 35

PAIN AND temperature loss on one side of face AND SAME side of body?

Back 35

brainstem lesion is OPPOSITE the side of the facial sensory loss ABOVE MIDBRAIN
STT CROSSES AT ANTERIOR WHITE COMMISSURE IN SC (crossed)
TRIGEMINOTHALAMIC TRACT OF P+T CROSSES AROUND MID-PONS (crossed)

Hint 35

081913_FM201_L_Brainstem2-Trigeminal

Front 36

When you whack the trigeminothalamic tract carrying MAIN SENSORY NUCLEUS AXONS from mid-pons up, what other sensation might you lose- why?

Back 36

You may lose 2 point discrimination and limb position from neck down
The trigeminothlamic tract, once crossed travels with the MEDIAL LEMNISCUS (carrying info from POSTERIOR COLUMNS)

Hint 36

081913_FM201_L_Brainstem2-Trigeminal

Front 37

Why would a high cervical cord injury cause P+T loss in the face?

Back 37

because you might whack the spinal5 tract and nucleus located in the caudal medulla. These are located at the level of the decussation (junction between spinal cord and brainstem.

Hint 37

081913_FM201_L_Brainstem2-Trigeminal

Front 38

What tracts carrying similar information (but one from face and one from body) are continuation of each other from cervical cord to brainstem?

Back 38

. Tract of Lisseur and Substantia Gelatinosa (normally carry pain and temp info from body) -->
Tract of Lisseur turns into spinal 5 tract in the caudal medulla
substantia gelatinosa turns into spinal5 nucleus in the caudal medulla

Hint 38

081913_FM201_L_Brainstem2-Trigeminal

Front 39

What is the only nucleus in the brainstem where afferent ganglion cell bodies actually live within the nucleus?

Back 39

Mesencephalic nucleus contains the dorsal root ganglion cell bodies carrying the jaw position sense from CN5

Hint 39

081913_FM201_L_Brainstem2-Trigeminal

Front 40

What 4 nuclei make an extended column throughout the brainstem?

Back 40

CN5-sensory; all of midbrain
N. solitarious (7,9,10)- visceral sensory; all of medulla
N. ambiguus (9.10)- motor; rostral medulla
CN12-motor; rostral medulla

Hint 40

082013_FM201_L_Brainstem3-MotorVisc

Front 41

Why is it that different locations (medial vs. lateral) in the brainstem indicate different vulnarabilities?

Back 41

Because medial vs. lateral brainsteam are supplied by different arteries (one part can be spared in a lesion)
MEDIAL- Somatic motor, CST
LATERAL- Branchial motor, All sensory, STT

Hint 41

082013_FM201_L_Brainstem3-MotorVisc

Front 42

What structures will you find in jnctn of spinal cord and brainstem?

Back 42

Decussation (CST crossing), STT (crossed), NG appearing, spinal5tract and caudal nucleus, solitarious

Hint 42

082013_FM201_L_Brainstem3-MotorVisc

Front 43

What structures will you find in CAUDAL MEDULLA?

Back 43

slit like central canal, CN12,NS and dorsal motor nucleus of the vagus, NG, NC, medial lemniscus, spinal 5 tract nucleus and tract, STT, medullary pyramid

Hint 43

082013_FM201_L_Brainstem3-MotorVisc

Front 44

What structures will you find in ROSTRAL MEDULLA?

Back 44

CN12motor, NA, solitarious, spinal5tract, dorsal motor nucleus of the vagus

Hint 44

082013_FM201_L_Brainstem3-MotorVisc

Front 45

What structures will you find in CAUDAL PONS?

Back 45

CN6,7motor, spinal5tract

Hint 45

082013_FM201_L_Brainstem3-MotorVisc

Front 46

What structures will you find in MID-PONS?

Back 46

CN5motor and main sensory nucleus, mesencephalic nucleus

Hint 46

082013_FM201_L_Brainstem3-MotorVisc

Front 47

What structures will you find in ROSTRAL PONS?

Back 47

CN4motor axons (nucleus is in CAUDAL MIDBRAIN)

Hint 47

082013_FM201_L_Brainstem3-MotorVisc

Front 48

What structures will you find in MIDBRAIN?

Back 48

CN3motor (ROSTRAL MIDBRAIN), CN4motor (CAUDAL MIDBRAIN)

Hint 48

082013_FM201_L_Brainstem3-MotorVisc

Front 49

What CNs carry PSNS axons? Where are the PSNS nuclei for each one?

Back 49

CN3- PSNS Nuclei are in the vicinity of the CN3motor nucleus (ROSTRAL MIDBRAIN)- onthe boards, call this edinger-westphal
CN7-PSNS nuclei are in the salivatory nucleus (location unimp)
CN9- PSNS nuclei are in the salivatory nucleus (location unimp)
CN10- Dorsal motor nucleus of the vagus in ROSTRAL MEDULLA
More PSNS scattered around in the reticular formationof ROSTRAL MEDULLA

Hint 49

082013_FM201_L_Brainstem3-MotorVisc

Front 50

So when CN3 nucleus is busted, the PSNS is often busted too- what are the clinical sx?

Back 50

UNILAT
. PSNS busted- full mydriasis
. CN3 busted- eye is down and out at rest (SO3LR4 OK), visual issues (diplopia,blurry vision), full ptosis (due to LPS being busted too CN3)

Hint 50

082013_FM201_L_Brainstem3-MotorVisc

Front 51

Why do unilateral CBT lesion have little effect? What is the effect? How would it be different in an LMN lesion?

Back 51

. All cranial nerves except CN7 going to lower face gets BILATERAL HEMISPHERIC input EXCEPT FOR CN7 lower face neurons (smile, puff out cheks etc)
. Thus in UMN (CBT) lesions between cortex and LMN, you see weakness of LOWER FACE, forehead is spared
. In an LMN lesion, the weakness would affect the WHOLE SIDE OF FACE, followed by significant ATROPHY

Hint 51

082013_FM201_L_Brainstem3-MotorVisc

Front 52

What else other than a UMN lesion can take out CN7 commonly? How to distinguish this from a UMN lesion?

Back 52

Most common CN7 palsy=Bell's palsy (PNS issue) --> recoverable
R/O UMN lesion --> it would be accompanied by loss of sensation or other clues, not just a single sx

Hint 52

082013_FM201_L_Brainstem3-MotorVisc

Front 53

When a brainstem lesion takes out CN6, why is 7 also gone?

Back 53

CN7 a branchial motor nerve does a loop around 6 before heading out

Hint 53

082013_FM201_L_Brainstem3-MotorVisc

Front 54

What is the most important function of the middle ear cavity?

Back 54

Air-fluid interface from middle to inner ear= 30 DB loss
The bones make up for this loss so the sound is not dampened

Hint 54

082313_FM201_L_EAR_rev

Front 55

What organs of the vestibular system detect what type of head position?

Back 55

Utricle macula: horizontal plane- linear acceleration--> stereocilia here are horizontal
Saccule maccula: vertical acceleration --> stereocilia here are lateral
Semicirc canal cristae: angular acceleration

Hint 55

082313_FM201_L_EAR_rev

Front 56

What happens if the otoconia on top of the gelatinous cupula in the utricle and sacule fall out of place?

Back 56

BPV- Benign positional vertigo --> need to get them inplace

Hint 56

082313_FM201_L_EAR_rev

Front 57

What is the tonotopic organization of the basilar membrane of the cochlea?

Back 57

High freq sounds --> base of cochlea (thick and dense,narrow, stiff)
Low freq sounds --> apex of cochlea (wide, thin and floppy)

Hint 57

082313_FM201_L_EAR_rev

Front 58

Is there only one stereocilia per hair cell?

Back 58

No, many stereocilia per hair cell

Hint 58

082313_FM201_L_EAR_rev

Front 59

How do hair cells work? What happens to the stereocilia to make it send a signal?

Back 59

Stereocilia on a hair cells are connected by tip-links (proteins)
Moving the tip-links --> short to long will open up the K+ channels (remember these are in endolymph) --> K+ influx= generation of SIGNAL!

Hint 59

082313_FM201_L_EAR_rev

Front 60

In the reticular lemina of Organ of corti, how many rows of hair cells are there?
What is their output- where is it going?

Back 60

. 1 row of inner hair cells--> 95% spiral ganglion cells are connected here (Type 1 afferents)
. 3 rows of outer hair cells --> 5% spiral ganglion cells connected here (Type 2 afferents)

Hint 60

082313_FM201_L_EAR_rev

Front 61

What are the efferents to the hair cells?

Back 61

. Efferents from brain can go either to IHC or OHCs

Hint 61

082313_FM201_L_EAR_rev

Front 62

If IHCs send most input to the brain, what is the function of the OHCs?

Back 62

Receive lots of efferents from the brain -->
Fine tunes the signal--> 306 vs 304 hz?
Resolution of hearing (ie: filtering out background/extra noise=cocktail party syndrome)

Hint 62

082313_FM201_L_EAR_rev

Front 63

What things can cause sensorineural damage?

Back 63

1- Noise (includes presbyacusis= cumulative nosi damage seen in the old)
2- Biochemical (Ototoxic drugs= aminoglycosides, cisplatin, loop diuretics- often hit OHCs)
3- Genetic (gap junction (connexin) mutations, cytoskeletal proteins in hari cells)

Hint 63

082313_FM201_L_EAR_rev

Front 64

Two treatments for hearing loss?

Back 64

1- Conductive hearing loss- hearing aids
2- Sensorineural hering loss- cochlear implants (if the problems is in cochlea)

Hint 64

082313_FM201_L_EAR_rev

Front 65

where are the distal and proximal ends of the spiral ganglion cells located?

Back 65

Distal: Synapse on hair cells
Proximal: Join cochlear nerve --> to brainstem

Hint 65

082613_FM201_L_CentralAuditory

Front 66

Which compartment of the cochlea are the hair cells located? What are the two compartments above and below it?

Back 66

Hair cells are in the scala medialis
Above compartment: scala vestibuli
Below compartment: scala tympani

Hint 66

082613_FM201_L_CentralAuditory

Front 67

What type of fluid fills the scala medialis? Do spiral ganglion cells synapse in this fluid?

Back 67

ENDOLYMPH fills scala medialis- it's high in K+
The area where spiral ganglion cells synapse is called PERILYMPH-low in K+

Hint 67

082613_FM201_L_CentralAuditory

Front 68

What is the sensory and motor functions of the hair cells?

Back 68

. Inner hair cells: SENSORY --> conveys frequency(pitch) and intensity (amplitude) info to CNS (in an economical way)
. Outer hair cells: MOTOR --> shortens/lengthens to provide sensitivity (FINE TUNE) to INNER HAIR CELLS (amplify low-intensity sound ora particular freq)

Hint 68

082613_FM201_L_CentralAuditory

Front 69

The cochlea transmits what TWO type of sound information?

Back 69

FREQUENCY (PITCH)
Intensity (AMPLITUDE)

Hint 69

082613_FM201_L_CentralAuditory

Front 70

How do we localize sound? Which nucleus? Where is it located?

Back 70

. HORIZONTAL SOUND LOCALIZATION done by TIME OF ARRIVAL @ SUPERIOR OLIVES
. Superior olives= pons (one of pontin nuclei) --> on the path of lateral lemniscus (on the way to inferior colliculus)
. After partially crossing, some axons from the cochlear nucleus will go to superior olives and some will go on to inferior colliculi

Hint 70

082613_FM201_L_CentralAuditory

Front 71

What are the roles of the efferents in the auditory system?
Where do we find these? (in between what structures?)

Back 71

. FUNCTION: To fine-tune the system:
ie: efeerents to the OUTER HAIR CELLS --> inhibit too much jiggling at the outer hair cells
. WHERE DO THEY EXIST: brainstem/thalamus; between auditory structures in brainstem; pontine auditory nuclei --> organ of Corti

Hint 71

082613_FM201_L_CentralAuditory

Front 72

What controls the STAPEDIUS MUSCLES and TENSOR TYMPANI?
What nucleus controls the responseof these muscles?
What are the roles of these muscles?

Back 72

. Both tensor tympani CN5, stapedius CN7 close in response to CERTAIN SOUNDS
. This reflex is processed at the SUPERIOR OLIVE
. Role : NOT PROTECTION FROM LOUD SOUNDS, possible to filter out low frequency background/extra noise (ie: bells palsy patients complain of hyperacusis)
. Tensor tympani also contracts before we chew/speak --> filters out our own noise or in response to VISUAL STIM

Hint 72

082613_FM201_L_CentralAuditory

Front 73

What parts of the auditory system have tonotopic organization?
What is the role of this?

Back 73

.Tonotopic organization: starts at basilar membrane (freq) and continues all the way to cortex
. Role of tonotopy: language? use for cochlear implants!

Hint 73

082613_FM201_L_CentralAuditory

Front 74

If there is loss of hearing in one ear --> where is the UNILATERAL lesion?
What type of damage is likely to produce that lesion?

Back 74

. Peripheral to the cochlear nuclei - anything ROSTRAL to this has crossed axons
. Conductive loss: external (ear wax) /middle ear (otitis, sclerosis, perf)
. Sensorineural loss: cochlea (ototoxic drugs), 8th nerve (tumor), cochlear nuclei (lateral brainstem infarct)

Hint 74

082613_FM201_L_CentralAuditory

Front 75

What is you had a UNILATERAL lesion ROSTRAL to the cochlear nucleus- what would this cause?

Back 75

. Unilateral lesion ROSTRAL to the COCHLEAR NUCLEUS will produce
1) INABILITY TO LOCALIZE SOUND
2) INABILITY TO FILTER OUT BACKGROUND NOISE

Hint 75

082613_FM201_L_CentralAuditory

Front 76

Where in the brainstem do you find the vestibular and cochlear nucleus, superior olive?

Back 76

. Vestibular starts at ROSTRAL MEDULLA---> CAUDAL PONS
. Cochlear around here too --> a little above the ROSTRAL MEDULLA
. Superior olive (localize sound) --> appears between ROSTRAL MEDULLA and CAUDAL PONS --> lateral lemniscus is not visible before the midbrain but it's there
. Can see LATERAL LEMNISCUS in MIDBRAIN as the stem of the wine glass going into the ICP

Hint 76

082613_FM201_L_CentralAuditory

Front 77

Where is the thalamus in relation to the midbrain?

Back 77

Anterior and superior to it BUT posterior thalamus hugs the midbrain

Hint 77

082613_FM201_L_CentralAuditory

Front 78

What is the role of the vestibular system?
What are the long tracts used to accomplish these?

Back 78

. Detects position of head in space (vestibular nuclei) --> adjusts
1) posture, muscle tone (output via VESTIBULOSPINAL tracts) and
2) eye movements (MEDIAL LONGITUDINAL FASCICULUS=MLF)

Hint 78

082713_FM201_L_EyeMovements

Front 79

What is the gelatinous cupula?

Back 79

Membrane that the stereocilia of the vestibular system are attached to --> denser than the endolymph

Front 80

What structures in the vestibular system are responsible for linear acceleration and head tilt?
What is the name of the sensory patch of epithelium here?
What other important structure is here (that is not in the semicircular canals)?

Back 80

. Utricle and saccule= LINEAR ACCELARATION, HORIZONTAL HEAD TILT
. Sensory epithelium=maculae
. Stereocilia are attached to a membrane called GELATIONOUS CUPULA
. The calcium carbonate crystals IN MACULAE= OTOCONIA (embedded in gelatinous cupula

Hint 80

082713_FM201_L_EyeMovements

Front 81

What structures in the vestibular system are responsible for angular acceleration?

Back 81

. Semicircular canals= ANGULAR ACCELERATION
. Sensory epithelium=cristae ampularis
. Membrane that stereocilia are embedded in= GELATINOUS CUPULA
. No otoconia here

Hint 81

082713_FM201_L_EyeMovements

Front 82

What is the role of the otoconia in the utricle and saccule?

Back 82

. When there's a tilt, membrane (gelatinous cupula) flops over
. Otoconia (the crystals)= weight;make sure that the GC stays flopped over
. Ensures that the stereocilia are getting the signal

Hint 82

082713_FM201_L_EyeMovements

Front 83

What are the inputs to the vestibular nuclei?

Back 83

1) Vestibular ganglio cells (head movements etc)
2) Cerebellum (vestibular)
3) Cervical spinal cord (about neck muscle activity)
* can't tell where the lesion is just because of a vestibular problem

Hint 83

082713_FM201_L_EyeMovements

Front 84

What are the outputs from the vestibular nuclei?

Back 84

1) to thalamus re: head position (not that imp)
2) to vestibular cerebellum
3) To spinal cord --> two tracts (medial and lateral vestibulospinal)
4) to motor nuclei 3,4, and 6 --> medial longitudinal fasciculus (MLF)= eye movements in coordination with head movements (reflex eye movements)

Hint 84

082713_FM201_L_EyeMovements

Front 85

What are the functions of the two vestibulospinal tracts going from the vestibular nuclei to the spinal cord?
What tract are they part of in the spinal cord?

Back 85

. Medial vestibulospinal tract-- head position, coordinates head with eye movements--> TO motor neurons of neck muscles
. Lateral vestibulospinal tract-- changes body posture to compensate for tilts or rotation of body/head -->TO motor neurons of antigravity muscles (EXTENSORS)
* These are part of the descending pathways from brainstem in the spinal cord --> the MEDIAL DESCENDING MOTOR TRACTS

Hint 85

082713_FM201_L_EyeMovements

Front 86

What are the two types of eye movements?

Back 86

. Vestibular reflex eye movements- AUTOMATIC (just vestibular to motor-visual system not involved)
. Voluntary eye movements- when we want to look at something

Hint 86

082713_FM201_L_EyeMovements

Front 87

What are the goals of the two type of eye movements (voluntary and automatic)?

Back 87

. Keep image from moving on the RETINA (so we can see with detail)
. VOR- adjusts optic axis using head movements
. Voluntary (pursuit) system- keeps images on fovea with visual feedback

Hint 87

082713_FM201_L_EyeMovements

Front 88

What are contributions of the vestibular nuclei to the reflex eye movements (vestibulo-ocular reflex=VOR)?
What structure/tract carries this info?
Which side to which side?

Back 88

. Medial longitudinal fasciculus (MLF) carries info from vestibular nuclei to motor nuclei 3,4,6 --> adjusts eye movements in response to head movements
. ie: KEEPS EYES LOOKING AT A SINGLE DIRECTION WHEN THE HEAD IS BEING MOVED
. The eyes are always YOKED during VOR

Hint 88

082713_FM201_L_EyeMovements

Front 89

What if you want to track a moving object with your head and eyes (how to overcome the VOR)?

Back 89

Cerebellar circuits suppress the VOR when you want to track an object with head AND eyes

Hint 89

082713_FM201_L_EyeMovements

Front 90

What controls the voluntary eye movements?
Is this related to the vestibular nuclei?
What are the requirements to SEE objects?

Back 90

. Voluntary eye movements are NOT related to vestibular nuclei
. Controlled by CEREBRAL CORTEX (OCCIPITAL)
. Requirements to see objects:
1) visual image falls on the FOVEA of both eyesfor 0.1 sec
2) image is stabilized during movement
3) object is in focus

Hint 90

082713_FM201_L_EyeMovements

Front 91

Are voluntary eye movements always yoked?

Back 91

No- CONJUGATE MOVEMENTS (both eyes same directions) ARE YOKED
VERGENCE MOVEMENT (two eyes different directions) ARE NOT YOKED

Hint 91

082713_FM201_L_EyeMovements

Front 92

What are the two tests used to test if voluntary movements are intact?

Back 92

. Saccades- ability to switch focus from one object to next with eyes (nose to finger)
. Pursuit or following movements- slower, smoother movements used to follow a moving target

Hint 92

082713_FM201_L_EyeMovements

Front 93

What part of the cortex is used to contol VOLUNTARY EYE MOVEMENTS?

Back 93

Frontal eye fields (frontal cortex) --> SACCADIC MOVEMENT TO OPPOSITE SIDE
. Horizontal saccades - EACH SIDE goes to opposite VIEW FIELD (BUT BOTH EYES MOVE)
. Vertical saccades- BOTH SIDES work together FOR UP AND DOWN MOVEMENTS

Hint 93

082713_FM201_L_EyeMovements

Front 94

What happens if an acute lesion (ie: stroke) damages the frontal eye field?

Back 94

. Tendency to gaze at the side TOWARDS THE LESION (but no diplopia- eyes are yoked)
. Cannot look at the OPPOSITE SIDE OF LESION (Saccadic movement impaired)
. UMN paralysis of lower face and body (CBT and CST are often impaired in this lesion due to proximity of FRONTAL EYE FIELDS TO MOTOR CORTEX)

Hint 94

082713_FM201_L_EyeMovements

Front 95

Pathway for frontal eye centers(voluntary eye movements) to get to motor nuclei in brainstem?

Back 95

Frontal eye fields (cortex) --< caudate nucleus --< substantia nigra --< SUPERIOR COLLICULUS --< Brainstem Gaze centers --<extraocular motor nuclei

Hint 95

082713_FM201_L_EyeMovements

Front 96

Does the superior colliculus talk directly to EXTRAOCULAR Motor Neurons?

Back 96

No
. Sup colliculus --< brainstem gaze centers --< extraocular motor nuclei

Hint 96

082713_FM201_L_EyeMovements

Front 97

What are brainstem gaze centers?
Where are they located?
Do they project to the same side

Back 97

. Brainstem Circuits that control horizontal, BUT ALSO vertical (up,down) and vergent movements (no other kind: conjugate or vergent)---< Then talk to 3,4,6 nuclei
. UP, DOWN and CONVERGE centers are near 3 and 4 motor nucleus in MIDBRAIN: UP=dorsal to aqueduct (BILAT), DOWN=ventral to aqueduct (BILAT), CONVERGE=unknown (just one)
. LATERAL centers are near 6 nucleus (LR) in CAUDAL PONS (BILAT)- called PPRF
. The gaze centers project IPSILATERAL

Hint 97

082713_FM201_L_EyeMovements

Front 98

How do brainstem gaze centers do to establish horizontal eye movements?
Why does lateral movement (LR) require that medial rectus also be activated?
How is this achieved?

Back 98

. CONJUGATE EYE MOVEMENTS are YOKED: for horizontal movement to one side, LR of one eye must go with MR of the other eye
. Done by connecting CN6 (LR) w/ CN3 (MRandAO) via MLF (medial longitudinal fasciculus that also carries axons from vestibular nuclei)

Hint 98

082713_FM201_L_EyeMovements

Front 99

What does the CN6 MOTOR NUCLEUS CONTAIN that is involved in the horizontal gaze?
Which side does each axon project?

Back 99

CN6 contains
1) Extraocular motor neurons to LR -->IPSILATERAL LR
2) Interneurons going to CN3 via MLF --> these CROSS (CONTRALATERAL CN3 nuclei) --> because the MR of CONTRALATERAL EYE must move

Hint 99

082713_FM201_L_EyeMovements

Front 100

Lesions of the vestibular system - what are they, what do they indicate?

Back 100

. Vertigo (spinning, less often tilting, leaning)= dysfunction in ANY part of vestibular system: peripheral (CN8, labyrinth) OR central (vest nuclei, cerebellum, other conn)
. Nystagmus (rhythmic uncoorinated eye movements), often accompanies vertigo attacks
. Poor balance

Hint 100

082713_FM201_L_EyeMovements

Front 101

If horizontal gaze is impaired (involving the medial rectus on one side) --> is convergent gaze (involving the same medial rectus) also impaired?

Back 101

. Depends on the lesion --> a contralateral CN6 motor lesion could take out LR and MR (OPP SIDES) but convergent gaze for that MR is controlled by the CN3 nucleus (intact)

Hint 101

082713_FM201_L_EyeMovements

Front 102

What is the syndrome caused by an MLF lesion?
What are the sx?
Cause?

Back 102

. Internuclear Opthalmoplegia --> MLF lesion UNILATERAL(carrying axons to CN3 nucleus for MR)
. Lose ADDUCTION IPSILATERAL (MR) BUT VERGENCE IS FINE (MR can abduct when STIM by CN3 or CONVERGE CENTER-no MLF involved) --> indicates that the problem is NOT an MR paralysis
. NYSTAGMUS of OPPOSITE EYE (Abducting eye)
. MS plaques/midline pontine infarcts

Hint 102

082713_FM201_L_EyeMovements

Front 103

The two eye movement systems work together to keep the image from moving on the retina- what if one system is overwhelmed? What clinical sx?

Back 103

NYSTAGMUS (rhytmic alternating reflex of yoked movesments)
- Slow phase (PURSUE) and fast phase (SACCADE)
- Up, down or torsion

Hint 103

082713_FM201_L_EyeMovements

Front 104

Can nystagmus be normal- how would a normal condition demonstrate nystagmus?

Back 104

Yes
1) OPTOKINETIC NYSTAGMUS- watching a landscape out the window = voluntary eye movements do the slow phase
. PURSUE (voluntary) an object until you can't roll the eye any further=SLOW --> SACCADE back to a new focus=FAST
2) POST-ROTATORY NYSTAGMUS- spinning around in chair = VOR responsible for slow phase
. Slow phase LEFT, fast phase RIGHT
3) CALORIC NYSTAGMUS- Pouring water into someone's ear--> moves the endolymph in semicircular canals
. Cold water --> OPPOSITE SIDE NYSTAGMUS (fast phase)
. Warm water --> SAME SIDE NYSTAGMUS (fast phase)

Hint 104

082713_FM201_L_EyeMovements

Front 105

When you dont see OKN, Post rot or CALORIC NYSTAGMUS, what is this mean?
What are reasons why you must see an ABNORMAL NYSTAGMUS?

Back 105

. Absence of OKN, Post rot or CALORIC NYSTAGMUS= investigate peripheral and central
. Spontaneous nystagmus: alcohol intox, damage to peripheral or central stuff

Hint 105

082713_FM201_L_EyeMovements

Front 106

Blood supply of cerebellum and brainstem: what do these supply:
PCA
SCA
AICA
PICA
Vertebral
Basilar

Back 106

. PCA (post. cerebral) - No CBM, Midbrain w/ BASILAR ARTERY
. SCA (SUP(main) CEREBELLAR ARTERY): Anterior+superior surface of CBM, all DEEP CBM nuclei, SCP; little of rostral pons
. AICA: Little of lateral and inferior CBM, caudal pons w/ BASILAR and PONTINE ARTERIES
. PICA: Little of posterior CBM, rostral medulla w/ VERTEBRAL ARTERY
. Vertebral artery+ Ant spinal arteries: Caudal medulla
* These big branches will send penetrating branches into the BSTEM: PARAMEDIAN (medially) and CIRCUMFERENTIAL (lateral)

Hint 106

083013_FM201_Conf_BS2-TractsVascular

Front 107

Is one more likely to survive a lateral or medial brainstem stroke?

Back 107

Lateral brainstem stroke (card/resp centers are not disturbed

Hint 107

083013_FM201_Conf_BS2-TractsVascular

Front 108

What are descending autonomic tracts?
Where do they run?

Back 108

. From hypothalamus/thalamus --> carry input to interomediolat columns
. Tracts run LATERALLY IN THE BRAINSTEM near STT

Hint 108

083013_FM201_Conf_BS2-TractsVascular

Front 109

When you see a Horner's syndrome- is the lesion ipsilateral or contra?

Back 109

. Horner's syndrome- lesion ALWAYS IPSI

Hint 109

083013_FM201_Conf_BS2-TractsVascular

Front 110

Medial vs. lateral structures (if vasculature is interrupted?) in medulla

Back 110

MEDULLA
Medial:12 (rostral), MLF, CST/CBT, medial lemniscus, NG-NF (very caudal)
Lateral: lateral cuneate (very caudal), dorsal nucleus of vagus (caudal-mid), 8 (rostral), 9-10=NA (rostral), NS (cardio/resp=rostral, taste=caudal), Spinal 5 nucleus (p&t=caudal medulla), STT (xed), Spinal 5 tract (P&T), ICP, autonomic control tracts
Both: crossing of olivocerebellar fibers (rostral), reticular formation (card/resp)

Hint 110

083013_FM201_Conf_BS2-TractsVascular

Front 111

Medial vs. lateral structures (if vasculature is interrupted?) in PONS

Back 111

PONS
Medial:6 (CAUDAL), MLF, CST/CBT, medial lemniscus(caudal)
Lateral: 5 (mid), 7 (caudal), medial lemniscus (mid-rostral), STT (xed), spinal 5 tract, spinal5nucleus (crude touch,corneal reflex=CAUDAL), main sensory nucleus, mesencephalic nucleus, MCP, autonomic control tracts
Both: crossing of griseum pontis fibers, reticular form (consciousness)

Hint 111

083013_FM201_Conf_BS2-TractsVascular

Front 112

Medial vs. lateral structures (if vasculature is interrupted?) in MIDBRAIN

Back 112

MIDBRAIN
Medial: 3,4 (dorsal), MLF, red nucleus, SCP fibers cross, inf/sup colliculus
Lateral: medial lemniscus, STT (xed), TGT (xed), lateral lemniscus, CST/CBT, corticopontine fibers, substantia nigra, autonomic tracts
Both: reticular formation (consciousness)

Hint 112

083013_FM201_Conf_BS2-TractsVascular

Front 113

Key functions of the caudal reticular formation?
Where are these located?

Back 113

. RR --> medullary control; lesion= resp arrest/death
. BP, HR --> input from NS (caudal); output to symp neurons
. Posture, muscle tone, locomotion pattern (FLEXOR TONE) --> reticulospinal tracts
. Hiccuping, coughing, sneeze, shiver,gag, vomit, laugh/cry -->weird
. Located in caudal pons/rostral medulla

Hint 113

090313_FM201_C_ReviewBrainstemCerebellum

Front 114

Key functions of the rostral reticular formation?
Where are these located?

Back 114

. Alert/conscious state --> connections of consciousness between cortex and RF
. Located in rostral pons/midbrain

Hint 114

090313_FM201_C_ReviewBrainstemCerebellum

Front 115

What is coma?
What kind of lesions result in a coma?
Do these have to be bilateral?

Back 115

. Unarousable/unconscious state in which you cannot elicit meaningful responses from cortical areas
. Lesions that destroy the connections between arousal centers (rostral RF) and cortex (can be thalamic, cortical or RF)
. For full coma --> lesion must be bilateral (unilateral can slightly impair alertness)

Hint 115

090313_FM201_C_ReviewBrainstemCerebellum

Front 116

What is the ascending reticular activating system- ARAS?

Back 116

. System invovled in behavioral alertness and arousal
. Rostral RF --> projects into this system
. Also input from all somatosensory nuclei, emotional/cognitive processes
. Thalamus and hypothalamus involved too

Hint 116

090313_FM201_C_ReviewBrainstemCerebellum

Front 117

Who are locked in patients?

Back 117

. Patients with bilateral damage in the rostral pons/ midbrain that spare the rostral RF and sensory movements
. Fully conscious with no movement (CST/CBT gone)

Hint 117

090313_FM201_C_ReviewBrainstemCerebellum

Front 118

Pathway of direct and consensual pupillary reflex fully awake and comatose patients?

Back 118

. Direct and consensual pupillary reflex
. Reticular ganglion cell --> CN2 nucleus --> optic chiasm (BILAT) --> BILAT input to pretectum
. BILAT INPUT to PREGANGLIONIC PSNS NEAR CN3 NUCLEUS --> ciliary ganglion --> BILAT miosis

Hint 118

090313_FM201_C_ReviewBrainstemCerebellum

Front 119

How do you distinguish a CN2 from a CN3 lesion with the pupillary reflex?

Back 119

Shinelight in one eye
. CN2 lesion--> BILAT UNRESPONSIVE (only when light is on the lesioned side)
. CN3 lesion --> UNILAT UNRESPONSIVE (when the light is on either side) --> ANISOCORIA (unequal size of pupils)

Hint 119

090313_FM201_C_ReviewBrainstemCerebellum

Front 120

What would you see in the eye if there's a full CN3 lesion vs. a partial CN3 lesion?

Back 120

. Full CN3 lesion --> blown pupil, depressed/out eye, complete ptosis
. Partial CN3 lesion -->
Compression will get the outer PSNS fibers (=blown pupil, can't accommodate)
Small vessel dz gets the inner CN3 axons (= full ptosis, blurry vision)

Hint 120

090313_FM201_C_ReviewBrainstemCerebellum

Front 121

What is another way to activate pupillary response (constriction) other than direct/consensual response (via CN2)?
What is the wiring here?

Back 121

. Moving gaze from far to near (accommodation)
. Wiring is through VISUAL CORTEX not CN2 IN, CN3 out
. Visual cortex --> pretectal area -->
1) PSNS near CN3 --> miosis and accommodation (rounder lens for near vision)
2) Convergent gaze centers --> CN3 nuclei of L, R --> medial rectus

Hint 121

090313_FM201_C_ReviewBrainstemCerebellum

Front 122

What is the wiring for mydriasis?

Back 122

Sympathetic input:
Hypothalamus --> lateral brainstem (ANS output tract here) --> Interomediolat columns (T1-T2) -->superior cervical ganglion --> carotid plexus (travel up on the internal carotid through the carotid sinus) --> pupil dilator muscle (TARSAL)
. Lesion anywhere along here can mess up the SNS

Hint 122

090313_FM201_C_ReviewBrainstemCerebellum

Front 123

How could a cortical lesion affect the jaw jerk? bilat/unilat?

Back 123

BILATERAL CORTICAL/UMN LESION could EXAGGERATE JAW JERK
Because there is BILAT INPUT TO CN5 motor neurons (efferent limb of jaw jerk)

Hint 123

090313_FM201_C_ReviewBrainstemCerebellum

Front 124

What would the VOR tell you in a comatose patient?
How would you test this?

Back 124

VOR can tell you what parts of the brainstem are intact (CN8, MLF, 3,4,6)
1) Doll's eye test (open eyes, move head side to side/up-down) --> if eyes remain fixated, most of brainstem is good
. Works without visual input/light
2) Caloric nystagmus (cold water infusion into one ear)
a) Cortex out, brainstem good --> Slow, tonic movement towards infused side with no fast phaseof nystagmus (cortex needed to generate saccades
b) Brainstem damaged --> no movement (BILAT DAMAGE), one eye kinda moves (UNILAT BSTEM DAMAGE)

Hint 124

090313_FM201_C_ReviewBrainstemCerebellum

Front 125

What would the corneal reflex tell you in a comatose patient?

Back 125

Intact corneal reflex=
OK CN5 SENSORY and BILAT CN7 MOTOR NUCLEI

Hint 125

090313_FM201_C_ReviewBrainstemCerebellum

Front 126

What would the gag reflex tell you in a comatose patient?

Back 126

OK 9 and 10

Hint 126

090313_FM201_C_ReviewBrainstemCerebellum

Front 127

How could you test a visceral reflex in a comatose patient?

Back 127

If 9-10 (afferent from carotid sinus) and NS (caudal)-efferent part is intact, BP and HR should both be up in the short term

Hint 127

090313_FM201_C_ReviewBrainstemCerebellum

Front 128

What are posturing reflexes seen in comatose patients?

Back 128

Comatose patients with CST/CBT gone --> only have activity from brainstem motor centers projecting to the SC (descending motor pathways from brainstem)
. Only seen in patients with CST/CBT damage

Hint 128

090313_FM201_C_ReviewBrainstemCerebellum

Front 129

What posturing reflexes would you see in a comatose patient?

Back 129

Response to pain
. FLEXOR ARM RESPONSE- upper limbs flexes, lower limbs extended --> CAUDAL LESION
. EXTENSOR ARM RESPONSE- all limbs are extended, except wrists are flexed -->MORE ROSTRAL LESION
.Can't localize to a single place

Hint 129

090313_FM201_C_ReviewBrainstemCerebellum

Front 130

Patients with which posturing reflexes have better prognosis?

Back 130

Flexor arm, extensor leg

Hint 130

090313_FM201_C_ReviewBrainstemCerebellum

Front 131

What causes a midbrain compression?
What happens in this?

Back 131

. Epidural hemorrhage, edema, tumor
. Brain is pushed down through the tenctorial notch- compromising the rostral brainstem (thus RF)

Hint 131

090313_FM201_C_ReviewBrainstemCerebellum

Front 132

What is the triad of symptoms in a midbrain compression?

Back 132

. COMA --> Reticular formation BILAT COMPRESSION
. Fixed (no response to light), BLOWN PUPIL (later), IMPAIRED EYE MOVEMENTS--> CN3 nerve/axons
. Hemiplegia, hyperreflexia
. Postural reflexes maybe

Hint 132

090313_FM201_C_ReviewBrainstemCerebellum

Front 133

How do you tx a midbrain compression?

Back 133

Dx early, tx promptly

Hint 133

090313_FM201_C_ReviewBrainstemCerebellum