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42 Cards in this Set

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where is the corticospinal tract located in the pons?
pyramidal fascicles
what are the pontine nuclei?
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
where are the 3 cerebellar peduncles located, and what do they carry?
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)
what are the stripes in the pons?
pontine fascicles
where is the motor nucleus of CN VII located?
in the pons where the nucleus ambiguus was in the rostral medulla
what is the path of cranial nerve VII alpha neurons as they leave the pons?
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)
what do alpha and gamma motor neurons do?
alpha muscles innervate skeletal muscle fibers

gamma muscles innervate muscle spindle fibers
what nucleus is shaped like a kidney bean?
cochlear nucleus
where is the cochlear nucleus located?
NW
what is the tonotopic organization of the cochlear nucleus?
higher pitched sounds along the inner curve and low pitched in the outer curve
where do cochlear nucleus outputs go?
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
what does the superior olivary nucleus do?
responsible for sounds localization in 3d space
what happens to hearing when there is damage to the auditory pathway in the brainstem on one side?
doesnt wipe out hearing b/c the cochlear nucleus has output bilaterally to the trapezoid bodies on both sides.
how does the vestibular nucleus communicate w/ the nuclei of III and VI
medial longitudinal fasciculus
if you see the floculus in a slice where are yo?
caudal pons (slice 1)
what slice can the facial colliculus be seen?
slice 2 of the pons
how does CN VI exit, and in which slice?
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
in slice 2 of the pons, what is the relation of the trapezoid body to the medial lemniscus?
the trapezoid bodies are just lateral to the medial lemniscus in slice 2
what is a corticobulbar fiber?
a fiber going from the cortex to a cranial nerve motor nucleus
why might a cortical lesion spare the upper half of the face but paralyze the lower half?
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
what identifies slice 3 of the pons?
the trigeminal nerve
where can the trigeminal motor nucleus be found?
slice 3 of the pons (middle pons) across the sulcus from the main sensory nucleus of V
fibers from the ____ put the head on the sensory homunculus of the medial lemniscus
sensory nucleus of V

(at the level of the mid pons)
the ___ nucleus controls the muscles of mastication
motor nucleus of V
why cant you see the spinal nucleus of V and spinal tract of V in the mid pons slice (slice 3)
they are caudal! the main sensory nucleus of V replaces the nucleus of the spinal tract of V
what identifies slice 4 of the pons?
NO CRANIAL NERVES!
its shape (4 and 5= kinda unique)
NOT 5 b/c NO DECUSSATIONS
where can the raphe nucleus be seen in the pons?
slice 4 and slice 5
where can the locus ceruleus be seen in the pons?
slice 4 and (slice 5?)
what does the lateral lemniscus carry?
auditory information going from the cochlear nucleus to the inferior colliculus to pinpoint the location of sounds in 3d space
in slice 4, what does the sensory homunculus of the medial lemniscus look like?
head is medial (added at mid pons by fibers from main sensory nucleus of V) and legs are lateral
what is located at the angle of the lateral and medial lemnicus in slice 4?
the spinothalamic tract (STT)
what slices are the superior cerebellar peduncles seen in? what kinds of fibers do they carry?
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
what slices are the middle cerebellar peduncles seen in? what kinds of fibers do they carry?
the middle cerebellar peduncles are seen in slice 1 and 2 and carry fibers from the pontine nuclei to the cerebellum
what slices are the inferior cerebellar peduncles seen in? what kinds of fibers do they carry?
the inferior cerebellar peduncles are seen in the medulla and slice 1 and carry olivocerebellar fibers from the ION to the cerebellum
what identifies slice 5 of the pons?
looks like slice 4 (kinda) but w/ 2 DECUSSATIONS
where does the trochlear nerve decussate?
in the roof of the cerebral aqueduct in slice 5

each trochlear nucleus innervates the contralteral LR muscle
where is the periaqueductal grey matter and what does it do?
it is located around the cerebral aqueduct in the upper pons and is responsible for pain control (lots of enkephalin neurons)
where can the mesencephalic nucleus of V be seen?
in the upper pons scattered throughout the periaqueductal grey matter
what are the superimposed homunculi in slice 5?
the spinothalamic tract and the dorsal column/medial lemniscus
what is the trigeminal thalamic tract?
the superimposed heads of the sensory homunculi from the nucleus of the spinal tract of V and the sensory nucleus of V
where does the trigeminal thalamic tract project?
the VPM
where do the leg and arm sensations in the superimposed homunculi in the medial lemniscus in slice 5 go?
the VPL