Ns: 02 Brainstem Ii

Front 1

where is the corticospinal tract located in the pons?

Back 1

pyramidal fascicles

Front 2

what are the pontine nuclei?

Back 2

pontine nuclei are part of the corticopontocerebellar tract. fibers from the cortex run down with the corticospinal tract. they are in the pyramidal fascicles. then they synapse on pontine nuclei (grey matter in the pons). then crossing fibers cross the pons and run into the middle cerebellar peduncle on the opposite side from where they came from. they are headed to the opposite cerebellum

Front 3

where are the 3 cerebellar peduncles located, and what do they carry?

Back 3

inferior: medulla. carries olivocerebellar fibers from the ION

middle: pons. carries corticopontocerebellar fibers. collateral fibers in the pyramidal fascicles synapse on pontine nuclei, cross over, and run into the middle cerebellar peduncle

superior: exit cerebellum and go into the corticospinal tract (are these cerebellar efferents)

Front 4

what are the stripes in the pons?

Back 4

pontine fascicles

Front 5

where is the motor nucleus of CN VII located?

Back 5

in the pons where the nucleus ambiguus was in the rostral medulla

Front 6

what is the path of cranial nerve VII alpha neurons as they leave the pons?

Back 6

they go out from the motor nucleus of CN VII ventromedially, loop around the nucleus of CN VI in the floor of the 4th ventricle (the facial colliculus), and veer ventrally again to exit just medial to CN VIII (at the pontomedullary junction)

Front 7

what do alpha and gamma motor neurons do?

Back 7

alpha muscles innervate skeletal muscle fibers

gamma muscles innervate muscle spindle fibers

Front 8

what nucleus is shaped like a kidney bean?

Back 8

cochlear nucleus

Front 9

where is the cochlear nucleus located?

Back 9

NW

Front 10

what is the tonotopic organization of the cochlear nucleus?

Back 10

higher pitched sounds along the inner curve and low pitched in the outer curve

Front 11

where do cochlear nucleus outputs go?

Back 11

BILATERALLY to the trapezoid body (both sides)
superior olivary nucleus (at PMJ?)
lateral lemniscus
inferior colliculus
branchium (arms) of the inferior colliculus
medial geniculate body of the thalamus
Heschl's gyrus

Front 12

what does the superior olivary nucleus do?

Back 12

responsible for sounds localization in 3d space

Front 13

what happens to hearing when there is damage to the auditory pathway in the brainstem on one side?

Back 13

doesnt wipe out hearing b/c the cochlear nucleus has output bilaterally to the trapezoid bodies on both sides.

Front 14

how does the vestibular nucleus communicate w/ the nuclei of III and VI

Back 14

medial longitudinal fasciculus

Front 15

if you see the floculus in a slice where are yo?

Back 15

caudal pons (slice 1)

Front 16

what slice can the facial colliculus be seen?

Back 16

slice 2 of the pons

Front 17

how does CN VI exit, and in which slice?

Back 17

CN VI identifies slice 2 of the pons. it goes straight down from the nucleus of VI to exit from the pontomedullary junction near the midline

Front 18

in slice 2 of the pons, what is the relation of the trapezoid body to the medial lemniscus?

Back 18

the trapezoid bodies are just lateral to the medial lemniscus in slice 2

Front 19

what is a corticobulbar fiber?

Back 19

a fiber going from the cortex to a cranial nerve motor nucleus

Front 20

why might a cortical lesion spare the upper half of the face but paralyze the lower half?

Back 20

the dorsal half of the facial nucleus goes to the upper half of the face

the ventral half of the facial nucleus goes to the lower half of the face

the ventral half of the facial nucleus receives innervation from the contralateral side only

the dorsal half of the facial nucleus receive innervation from both sides of the cortex

a cortical lesion will cause paralysis on the contralateral lower half of the face, sparing the rest

contralateral tongue may also be affected for same reasons

remember these are called corticobulbar fibers

Front 21

what identifies slice 3 of the pons?

Back 21

the trigeminal nerve

Front 22

where can the trigeminal motor nucleus be found?

Back 22

slice 3 of the pons (middle pons) across the sulcus from the main sensory nucleus of V

Front 23

fibers from the ____ put the head on the sensory homunculus of the medial lemniscus

Back 23

sensory nucleus of V

(at the level of the mid pons)

Front 24

the ___ nucleus controls the muscles of mastication

Back 24

motor nucleus of V

Front 25

why cant you see the spinal nucleus of V and spinal tract of V in the mid pons slice (slice 3)

Back 25

they are caudal! the main sensory nucleus of V replaces the nucleus of the spinal tract of V

Front 26

what identifies slice 4 of the pons?

Back 26

NO CRANIAL NERVES!
its shape (4 and 5= kinda unique)
NOT 5 b/c NO DECUSSATIONS

Front 27

where can the raphe nucleus be seen in the pons?

Back 27

slice 4 and slice 5

Front 28

where can the locus ceruleus be seen in the pons?

Back 28

slice 4 and (slice 5?)

Front 29

what does the lateral lemniscus carry?

Back 29

auditory information going from the cochlear nucleus to the inferior colliculus to pinpoint the location of sounds in 3d space

Front 30

in slice 4, what does the sensory homunculus of the medial lemniscus look like?

Back 30

head is medial (added at mid pons by fibers from main sensory nucleus of V) and legs are lateral

Front 31

what is located at the angle of the lateral and medial lemnicus in slice 4?

Back 31

the spinothalamic tract (STT)

Front 32

what slices are the superior cerebellar peduncles seen in? what kinds of fibers do they carry?

Back 32

the superior cerebellar peduncles carry efferent cerebellar fibers "to talk to the cortico spinal tract"
the SCP are seen in slice 4 and 5 of the pons. they ducussate in slice 5

Front 33

what slices are the middle cerebellar peduncles seen in? what kinds of fibers do they carry?

Back 33

the middle cerebellar peduncles are seen in slice 1 and 2 and carry fibers from the pontine nuclei to the cerebellum

Front 34

what slices are the inferior cerebellar peduncles seen in? what kinds of fibers do they carry?

Back 34

the inferior cerebellar peduncles are seen in the medulla and slice 1 and carry olivocerebellar fibers from the ION to the cerebellum

Front 35

what identifies slice 5 of the pons?

Back 35

looks like slice 4 (kinda) but w/ 2 DECUSSATIONS

Front 36

where does the trochlear nerve decussate?

Back 36

in the roof of the cerebral aqueduct in slice 5

each trochlear nucleus innervates the contralteral LR muscle

Front 37

where is the periaqueductal grey matter and what does it do?

Back 37

it is located around the cerebral aqueduct in the upper pons and is responsible for pain control (lots of enkephalin neurons)

Front 38

where can the mesencephalic nucleus of V be seen?

Back 38

in the upper pons scattered throughout the periaqueductal grey matter

Front 39

what are the superimposed homunculi in slice 5?

Back 39

the spinothalamic tract and the dorsal column/medial lemniscus

Front 40

what is the trigeminal thalamic tract?

Back 40

the superimposed heads of the sensory homunculi from the nucleus of the spinal tract of V and the sensory nucleus of V

Front 41

where does the trigeminal thalamic tract project?

Back 41

the VPM

Front 42

where do the leg and arm sensations in the superimposed homunculi in the medial lemniscus in slice 5 go?

Back 42

the VPL