NEURO LEC 7: BRAINSTEM Flashcards by Chavez Girls

What are the 3 longitudinal divisions of the brainstem?

Basilar - front (boobs)

Tegmentum - middle (but think posterior brainstem, TUSH in the back)

Tectum - back

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The tectum is only found in the….

Midbrain

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What does the tectum consist of?

Superior + inferior colliculus and pretectum

visual and auditory processing and reflexive eye movements

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What is inside of the tegmentum

sensory nuclei and ascending sensory tracts (its in the back!)

Reticular Formation

CN V nuclei

medial longitudinal fasciculus (coordinates head and eye mvmt)

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What is inside of the basilar division?

descending axons from cerebral cortex, corticospinal, corticobrainstem, corticopontine, and corticoreticular tracts

Motor nuclei from substantia nigra, pons, and inferior olive

Basically a bunch of motor stuff (all tracts that start with cortico-)

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What is in the basis pedunculi?

Cerebral peduncles (motor tracts from cortex)

substantia niagra nucleus

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What’s in the MIDBRAIN tegmentum?

ascending sensory tracts

superior cerebellar peduncle (sensory from midbrain to cerebellum)

red nucleus

medial longitudinal fasiculus

periaqueductal gray

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What does the superior colliculus do?

motor and sensory info to orient head and eyes

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What does the inferior colliculus do?

relays info from cochlear nerve to superior colliculus and thalamus

auditory processing

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The pretectal area of the midbrain does what?

mediates eye reflexes

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What kind of matter is the red nucleus made out of?

Gray matter

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What cranial nerve nuclei are found in the midbrain tegmentum

3 and 4

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Pons forms the anterior wall of what?

fourth ventricle

cerebellum is posterior wall

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What 2 tracts synapse in the pons? Most of the tracts do not

corticopontine tract- Synapse on pontine nuclei -> pontocerebellar fibers -> middle cerebellar peduncle -> synapse in contralateral cerebellar hemisphere

corticobrainstem tract - synapses with trigeminal motor nucleus and facial nucleus

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What kind of fibers are in the superior cerebellar peduncle?

need to check

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What can you find in the basilar portion of the pons?

Descending tracts- corticospinal, corticobrainstem, corticopontine

Pontine nuclei

Pontocerebellar axons

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What can be found in the tegmentum of the Pons?

Sensory Tracts

Reticular Formation

Autonomic pathways

CN 5,6,7,8 nuclei

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What cranial nerve nuclei exits between the pyramid and inferior olive?

CN 12

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Which cranial nerves exit in the lateral groove of the medulla, lateral to olive?

IX, X

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What is the nucleus ambiguus for?

Motor output to swallowing/vocalization muscles

(Which would be CN 9, 10, and sometimes 12?)

BIG MOUTH

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inferior olivary nuclei receive info from many cortical and SC motor areas and then project where?
what info are they sending?

contralateral cerebellum through olivocerebellar tract

motor learning, timing and control of ongoing movements

nuclei of CN __ at medullopontine junction

VIII

What is the only tract that enters the medulla from the cerebellum

(The rest enter medulla -> _____ cerebellar peduncle -> cerebellum)

Cerebellovestibular tract

(starts with cerebellar because its coming from there!)

INFERIOR cerebellar peduncles (medulla is lowest, so inferior peduncles)

Solitary nucleus - CN’s and fxn

7, 9, 10

taste, oral sensations and visceral sensations (vagus/X)

Solitary confinement - inside sensations and bad food

The DCML crosses in the inferior medulla ________ to the crossing of the corticospinal tract

Posterior sensory in the back! motor in front

what vessels supply the midbrain?

PCA, branches of basilar artery SCA not on slide

what supplies the medulla with blood?

PICA, anterior spinal artery vertebral and posterior spinal arteries on pic but not slide so don't stress

What supplies the pons with blood?

AICA, basilar

What are the 4 brain stem tracts?

Rubrospinal Vestibulospinal Reticulospinal Tectospinal RVRT

What are the general brain stem functions

Modulates consciousness - reticular formation Regulates vital signs Conveys signal from cortex to spinal cord

*What are the 4 cardinal signs of brain stem dysfunction? 4 Ds

Dysphagia, Dysarthria, diplopia, dysmetria dysarthria - "articulate" difficulty speaking diplopia - double p for double vision

what specific part of the brainstem regulates vitals? Damage to brain stem could cause….

medullary and pontine centers Heart to stop beating BP to fluctuate Breathing to stop

Disorders of conciousness are due to damage of_______

Reticular activating formation/ reticular formation People in vegetative or minimally concious states have loss of tissue in subcoritcal/thalamic/brainstem regions

brainstem lesions will cause ____ signs vs single cranial nerve or cranial nuclei lesion will cause ____ signs

contra or ipsi - depends on where tracts cross and where the damage was ipsilateral

lesions of ______ and _____ tracts in the brainstem usually cause contralateral signs because these tracts cross the midline in the inferior medulla

lateral corticospinal dorsal column tracts

Anteriormedial midbrain syndrome (webers) is caused by….

Blockage of PCA or Basilar artery

What are the primary structures affected by Anteromedial midbrain syndrome (webers)

Corticospinal tract- contralateral motor paralysis Occulomotor nerve nucleus- Ipsilateral loss of eye movements. Paralysis of eyelid, dilated pupil (PTOSIS) Red Nucleus- loss of motor coordination, ataxia, CONTRALATERAL, inappropriate laughing and crying. Lability

What does CN3 palsy look like?

Eye deviated down and out

Lateral inferior pontine syndrome is due to occlusion of the….

Anterior inferior cerebellar artery

What are the clinical manifestations of lateral inferior pontine syndrome Think: What CN nuclei are there? Ipsi vs Contra effects? What tracts affected?

CN V - ipsi facial pain & temp sensation loss CN VII - ipsi facial weakness and expressions salivatory nucleus (CN VII, IX) - decr tears and salivation CN VIII - hearing loss, dysequilibrium, nausea spinothalamic tract - contra pain and temp sensation loss for body sympathetic nerve fibers - ipsi horners syndrome

Damage to what nerve causes Bell’s palsy How will Bell’s palsy differ from a facial weakness after stroke

Facial nerve - ipsi, whole half of face Stroke is usually only lower facial weakness on CONTRA side | (Upperface muscle preserved due to dual innervation of the upper face)

What is Horner’s syndrome?

Miosis- pupil constricted Ptosis- drooping eye lid Anhidrosis- drying of skin in the area (look at the word) Damage to sympathetic nerves

Locked in syndrome is due to damage of the….

Basiliar artery impacting the ventral pons bilaterally

What are the primary structures involved in locked in syndrome-

B corticospinal tracts- paralysis below the head B corticobulbar tracts- paralysis of facial muscles B abducens tracts- unable to move eyes to side Note: most of the time cranial nerve 3 is preserved but sometimes its impacted

What are spared in locked-in syndrome?

Reticular activating formation/ reticular formation Vertical gaze centers are spared.

Middle medullary syndrome is caused by a blockage in the ….

Anterior spinal artery

What is the 2nd most common place to have a stroke in the brainstem?

AICA

What are the primary structures affected by MEDIAL medullary syndrome what's medial in the medulla? what CN? tracts?

hypoglossal nerve- ipsilateral tongue protrusion DCML- contralateral loss of DCML senses (light touch, proprioception, vibration) Lateral corticospinal- contralateral hemiparesis (weakness or paralysis to side of body) Remember the hypoglossal nerve comes off of the medial medulla!

What is the most common brainstem stroke, and what artery causes it?

Lateral medullary syndrome (wallenberg) Due to blockage of PICA

What structures are affected due to Wallenberg syndrome (lateral medullary syndrome)

Vagus nerve/Solitary nucleus- elevated HR Vestibular nucleus- balance Vagus nerve nucleus- altered vitals Trigeminal Nerve Inferior cerebellar peduncle - ataxia/coordination ipsilateral Salivatory nucleus - unable to salivate or make tears Spinothalamic tract- contralateral Descending sympathetic- ipsilateral Horner syndrome Nucleus ambiguus (9 10) and 12 cranial nerve. Tongue/ larynx/pharynx affected. Lack of gag reflex, speech issues

The reticular formation is in the _______ of the pons

tegmentum