L8: Pons

boundaries of pons

1. caudal

   1. posterior pontine protuberance to the 4th ventricle

2. rostral

   1. anterior pontine protuberance to point behind inf colliculus

what happens to the corticospinals/bulbars as we move up the pons

they spread out more

what happes to the sensory structures as we move up the pons

whale - low

boomerang - high

name and view

anterior and posterior pontine protuberance - borders of pons

ventral aspect

a

base (of pontine protuebrance)

name red thing

basilar sulcus for basilar artery

vertebrals make of basilar

name arrow and what is in it

facial colliculus

nucleus of 7

root of 6

arrow 2 adn whats in it

lateral recess

has vestibular nuclei

its a depressed area

name arrow

middle cerebellar peduncle

what do peduncles communicate w

cerebellum

? structure

inferior cerebellar peduncle of medulla

name pink arrow

CN V

big bc it has 3 parts

yellow lines

CN 6

green arrow

CN VII

where are CN 6 and 7

low pons

where do we expect to see most CN coming off (ventral or dorsral)

ventral - they are trying to get towards the EOMs

EXCEPT 4 comes out the back (dorsal)

blue arrow

CN 4

isthmus pons level

low pons level CN

6 and 7

mid pons level CN

V

isthmus pons level CN

4

what view

low pons

blue

longitudinal bundle

• houses corticobulbars and spinals — pyramidal tract

low pons

pink body

medial lemniscus - dorsal

low pons

pink tail

ventral and lateral spinothalamics and spinotectal tracts

dorsal - sensory

low pons

whale hat

ventral trigeminothalamic tract - new

low pons

pink dots

pontine gray (nucleii)

so stains light

purple line

transverse fibers (pontocerebellars)

fxn of cerebellum

modulate and refine motor activity

name

facial colliculus

light pink

nucleus of 6

low pons

name white line

root of 7

low pons

teal

lateral recess

red arrow

vestibular nuclei

name these lines in low pons

travel parallel in low pons

7 - later = lateral

pink circle

CN 6 nucleus

LMN

hot pink circle

CN 7 motor nucleus

name moon and medium pink

spinal nucleus and tract of V

low pons

this is lower than it comes in so its dipping towards the spine

uncrossed general sensory info from head - esp pain

purple arrow

internal genu of VII (7)

name blue

medial longitudinal fasciculus

name orange arrows

nucleus raphe magnus —> serotonin

Pontine Paramedial Reticular Formation (PPRF)

low pons

whats this a cut of

mid pons

name purple and red

pontine protuberance - purple

basilar sulcus -

name blue

longitudinal bundle

corticobulbars adn spinals

mid pons

name pink and purple

pontine gray - pink

transverse fibers (pontocerebllars)- purple

name

medial lemniscus

ventral and lateral spinothalamics, spinotectal

still kinda a whale w a tale

orange

ventral trigeminothalamic tract

b and c

b - medial lemniscus

c - ventral and lateral spinothalamics, spinotectal

what does the C and G mean

cuneatus adn gracilis - its all medial lemnsicus here but those fibers are more in that area

rostral more medial and caudal more lateral

mid pons

blue

MLF

where do we see CN 5 in mid pons

Middle cerebellar peduncle

yellow

trigeminal nerve in MCP

pink circle

motor nucleus of 5

lateral pink circle

chief sensory nuc of 5

medial is more motor

green arrow

superior cerebellar peduncle

black arrow

mesencephalic root of 5

do we see nuc of CN 4 in isthmus pons

NO, just nerve itself

what cut of pons cuts thru superior cerebellar peduncle

isthmus pons

whats this a cross section of

isthmus pons

name

longitudinal bundles

corticospinals and bulbars

isthmus pons

pink

pontile gray

transverse fibers not obvious

hot pink

medial lemniscus

gray arrow

lateral lemniscus

light pink

central and lateral spinothalamics and spinotectals

orange

ventral trigeminothalamic tract

red area

superior cerevellar peduncle

yellow

decussation of superior cerebellar peduncle

blue

MLF

orange arrow

decussation of CN 4

how does CN 4 exit the brainstem

dorsally

green arrow

CN 4

whats this openingn

4th ventricle

• working up to cerebral aqueduct which is circular

which is more fragile 6 or 4

4 bc it takes the long way around

comes out the back way and goes around

where does CN 4 cross

anterior/ superior medullary velum

name

locus ceruleus

catecholamines - esp norepinephrine

what makes CN 4 unique

1. only CN to exit dorsally

2. only CN to totally cross

3. only CN to innervate EOM on dorsal aspect

4. small and delicate and prone to trauma

whats the patterns for a right CN 4 palsy

1. R hyper deviation

2. worse in left gaze

3. worse on R head tilt