S2 Neuro Exam 2: Caudal Pons & Pontomedullary Jxn

Front 1

where do the pontine nuclei migrate from? where do they go to?

Back 1

from: derived from alar plate, migrate ventrally and medially
to: form the basilar pons.

(will form sensory portions of associated CNs)

Front 2

what will the axons from the migrated pontine nuclei form?

Back 2

the middle cerebellar peduncle that wraps around the brainstem in a lateral position

Front 3

In the development of the pons, what does the basal plate form?

Back 3

-motor (pontine cranial) nuclei of pontine tegmentum
-the midline and dorsal motor components of cranial nerve nuclei

*(Pons is from rhombencephalon (metencephalon))

Front 4

The pontine tegmentum is 1 of the 2 major divisions of the pons. What is the pontine tegmentum a rostral continuation of?

Back 4

medullar reticular formation, cranial nerve nuceli, and ascending tracts.

Front 5

what is contained in the pontine tegmentum?

Back 5

pontine cranial nerve nuclei and ascending sensory tracts

(pontine cranial nerve nuclei does NOT = pontine nuclei)

Front 6

The basilar pons is the 2nd major division of the pons. what two tracts run through the basilar pons?

Back 6

corticobulbar and corticospinal

(*in addition to pontine nuclei & middle cerebellar peduncle)

Front 7

In the pons, where is the pontine cranial nerve nuclei located? where is the pontine nuclei located?

Back 7

pontine cranial nerve nuclei - pontine tegmentum
pontine nuclei- basilar pons

Front 8

at what level in the pons is the Cochlear component (SSA) of CN 8 located?

What info do the axons from the cochlea (spiral ganglia) carry to the brainstem?

Back 8

ponto medullar junction


auditory info

Front 9

where are the cell bodies of origin located for the cochlear component?


What do axons from cochlear nuclei eventually FORM?

Back 9

dorsal cochlear nucleus and ventral cochlear nucleus


LATERAL LEMNISCUS
(primary ascending auditory pathway)

Front 10

Do the cochlear component fibers cross? if so, where?

Back 10

yes: primarily cross midline at more rostral levels in the TRAPEZOID BODY and in the dorsal and intermediate acoustic stria.
(go on to form lateral lemniscus, some axons synapse in superior olivary nucleus)

Front 11

which number labels the trapezoid body?

nucleus of trapezoid body?

Back 11

8

9

Front 12

what is the origin of the efferent cochlear bundle?

Back 12

superior olivary nucleus

Front 13

what reflex is the superior olivary nucleus involved in? Via which CN?

Back 13

reflex for sound dampening via CN 7 (stapedius)

Front 14

in the ponto medullary junction, what is included in the central processing nuclei?

Back 14

nucleus of the trapezoid body, superior olivary nucleus and nucleus of the lateral lemniscus.

Front 15

Name the colored parts.

Back 15

red: superior olivary nucleus
orange: nucleus of the trapezoid body.

Front 16

Axons from the cochlear nuclei containing info from accessory, collect primarily where?

Back 16

in the contralateral lateral lemniscus.

Front 17

Q: Axons in the lateral lemniscus arise primarily from neurons located ......?

Back 17

in the dorsal ventral cochlear nuclei

*ascend bilaterally w/ a contralateral predominance

Front 18

Where do the axons from the central processing nuclei ascend to? (3)

Back 18

inferior colliculus
medial geniculate body (thalamus)
Cortex (temporal, transvers gyri of Heschel= consious perception)

Front 19

why doesn't an ipsilateral lesion cause a hearing loss (usually)? what are the exceptions?

Back 19

because the lateral lemniscus travels bilaterally with a contralateral predominance.
exceptions: the nerve or cochlear nuclei are involved.

Front 20

how many nuclei are innervated by the vestibular component of the vestibulocochlear nerve? what are they?

Back 20

4;
medial vestibular (yellow)
lateral vestibular (deiter's) (green)
superior vestibular (orange)
inferior vestibular (blue)

Front 21

how do the projections of the vestibular nuclei reach the cerebellum?

Back 21

via the juxtarestiform body located in the lateral vestibular nucleus.

*juxtarestiform body = balance, coordination

Front 22

T/F
There are some direct connection of the vestibulocochlear nerve to the flocculonodular lobe.

Back 22

TRUE!

Front 23

what is the function of the juxtarestiform body?

Back 23

balance coordination

Front 24

what are the two vestibular related nuclei/ structures?

Back 24

oculomotor nuclei and thalamus

Front 25

Via what structure do the vestibular related pathways have an impact on balance? how?

Back 25

Both are via the medial longitunal fasciculus.
Thalamus: Projects to cortex to give conscious perception of equilibrium and orientation

Front 26

what 2 tracts relates the vestibular pathway and the spinal cord?

Back 26

lateral vestibulospinal tract and medial vestibulospinal tract

(each from associated nuclues)

Front 27

what is another name for the medial vestibulospinal tract?

Back 27

Medial longitudinal fasciculus

Front 28

what is the function of the medial vestibulospinal tract?


function of lateral vestibulospinal tract?

Back 28

inhibitory to neck and upper trunk muscles; contributes to head-righting reflexes in relation to vision

excitatory to extensor spinal alpha motorneurons

Front 29

Besides CN 8, the caudal pons conatins the nuclei for which two CNs?

Back 29

6 and 7

Front 30

where does the facial nerve exit the brainstem?

Back 30

just anterior to CN 8 at pontomedullar junction
(@ level of 6 & 7)

Front 31

describe the course of the facial nerve.

Back 31

axons loop around the nucleus of CN 6 and exit ipsilaterally.

Front 32

what indicates the presence of the abducens nucleus?

Back 32

the bump on the floor of the 4th ventricle

Front 33

what surrounds the abducens nucleus?

Back 33

facial colliculus (facial fiber axons)

Front 34

are the axons that form the loop in the pathway of the facial nerve primarily sensory or motor?

Back 34

motor

Front 35

Name the colored "bump" on the floor of the 4th ventricle.

Back 35

Facial colliculus
(^surrounding abducens nucleus & axons of CN 7)

Front 36

how does cortical innervation from the facial nerve differ when innervating muscles of the forehead vs muscles of the lower face?

Back 36

bilateral innervation to the muscles of the forehead, contralateral to muscles for the lower face.

Front 37

If there is a lesion of the motor nucleus in the pons, what kind of paralysis should we find of the facial muscles?

Back 37

ipsilateral forehead paralysis, contralateral paralysis to mouth and chin.

Front 38

what kind of fibers does the intermedius branch of the facial nerve contain?

Back 38

GVE (parasympathetic functions), SVA and GSA

Front 39

For the parasympathetic aspect of the intermedius branch of the facial nerve, which nuclei is involved?

Back 39

superior salivatory nucleus (GVE)

Front 40

detail the pathway that starts at the limbic system and affects the intermedius branch of the facial nerve resulting in weeping and mouth watering to odors.

Back 40

GVE from limbic system and olfactory areas through hypothalamus to the brainstem via the dorsal longitudinal fasciculus.

Front 41

signals from the brainstem on the intermedius branch of the facial nerve result in?

Back 41

reflex lachrymation and gustatory stimulation of salivation

Front 42

describe the pathway of the solitary nucleus (specifically gustatory nucleus). Detail it from mouth to cortex.

Back 42

Begins with (SVA) sensory fibers from taste buds on anterior 2/3 tongue and hard and soft palates that run in chorda tympani from geniculate ganglion. Then it will project into the brainstem as intermedius nerve and enter the tractus soliatrius to synapse in the rostral portion of the nucleus. The nucleus then sends the info via the central tegmental tract to the thalamus which projects it to cortex.

Front 43

which portion of the solitary nucleus is specifically for gustatory nucleus?

Back 43

rostral portion

Front 44

what tract is used by the solitary nucleus to project taste fibers to the thamalus?

Back 44

central tegmental tract

Front 45

which part of the thalamus are the taste fibers from the solitary nucleus projected too?

Back 45

ventral posteromedial

Front 46

what two parts of the ear are innervated by the intermedius nerve?

Back 46

skin of the ear wall of acoustic meatus and external tympanic membrane.

Front 47

what nucleus supplies the GSA for the intermedius nerve?

Back 47

spinal trigeminal nucleus

(via geniculate ganglion)

Front 48

what is the pathway of the GSA fibers of the intermedius nerve?

Back 48

axons innervating areas around ear enter brainstem in the nervous intermedius and descend in spinal tract of trigeminal to synapse at the spinal V nucleus.

Front 49

Label each nervous intermedius colored tract with the appropriate fiber (GSA, GVE, etc)

Back 49

Red: GVE
purple: SVA
blue: GSA

Front 50

via what sulcus does the abducens nerve exit?

Back 50

inferior pontine

Front 51

what is the function of the abducens nerve?

Back 51

motor innervation to ipsilateral lateral rectus muscle of the eye.

Front 52

what is one of the most frequently injured CN that also has a long intracranial course?

Back 52

abducens nerve

Front 53

what nuclei does the abducens nerve have a complex central connection?

Back 53

oculomotor nuclei

Front 54

What CN exhibits this path?

Back 54

abducens

Front 55

how does the abducens nerve interact with the oculomotor nucleus?

Back 55

via medial longitudinal fasciculus

Front 56

The pontine reticular formation contains many nuclei contributing to the recticular formation.
What do the rostral projections of the reticular formation regulate?
where do they project to?

Back 56

regulate consciousness and caudal projections (thalamus).

Front 57

what do the caudal projections of the reticular formation regulate?

Back 57

motor and sensory functions

Front 58

what two tracts run through the substance of the basilar pons?

Back 58

corticospinal and corticonuclear tracts

Front 59

label all of the colored nuclei.

Back 59

:)

Front 60

at what level in the brainstem does the medial lemniscus reach its midline position?

Back 60

Medulla Levels (after medulla-pons junction)

Front 61

In the pons, are the major tracts located?

Back 61

caudal pons.

Front 62

what tract alway runs in tandem with the ALS?

Back 62

rubrospinal tract

Front 63

name the three subdivision of the trigeminal nucleus. which one is most rostral? most caudal?

Back 63

pars oralis (rostral), pars interpolaris, pars caudalis (caudal).

Front 64

which subdivision of the trigeminal nucleus are you most likely to see at the region of the caudal pons?

Back 64

pars oralis.

Front 65

what are the major tracts that enter the cerebellum beginning at the pontomedullary junction?

Back 65

inferior cerebellar peduncle (restiform body) enters the cerebellum with vestibulocerebellar projections (juxtarestiform body)

Front 66

which tract wraps latterally around the inferior peduncle at the pontomedullar junction?

Back 66

middle cerebellar peduncle

Front 67

Name the colored regions. What part of the brainstem is this?

Back 67

pontomedullar junction

Front 68

what two structures make up the roof of the fourth ventricle?

Back 68

superior cerebellar peduncles and superior medullar velum

Front 69

what is the blood supply to the caudal pons?

Back 69

vertebral arteries, basilar artery, posterior inferior cerebellar artery, anterior inferior cerebellar arteries.

Front 70

What is the major blood supply to just the pontomedullary junction?

Back 70

vertebral & medial branches of the basilar (yellow) &
posterior inferior cerebellar artery (blue)

Front 71

what is the major blood supply to just the caudal pons?

Back 71

branches of the basilar artery: paramedian (red), and short (yellow) and long (blue) circumferential branches.

(May also be supplied by anterior inferior cerebellar artery. AICA)

Front 72

Q: What cranial nerve exits here?

Back 72

hypoglossal nerve (CN 12)

Front 73

Q: A lesion in the area indicated in the above figure is most likely to affect which cranial nerve?

Back 73

CN 6

(corticospinal tract)

Front 74

Q: The tract btwn CN 3 & 4 that carries information to coordinate eye movements is the __________________

Back 74

medial lemniscus fasciculus

Front 75

Obj.
List Cranial nerves of the pontomedullary junction

Back 75

CN 8 (vestibular)- cochlear component (SSA) & vestibular component
CN7 (facial)- motor & intermediate branch
CN6 (abducens

Front 76

Obj.
Nuclei of cranial nerve 8 (cochlear component) & associated functions

Back 76

**dorsal & ventral cochlera nuclei- recieve axons from cochlear spiral ganglion
nucelus of trapezoid body- sound localization
superior olivary nucleus- sound localization & reflex sound dampening via CN 7 stapedius & CN 5 tensor tympani
nucleus of lateral lemniscus- sound localization & acoustic reflex

Front 77

Obj.
Nuclei of cranial nerve 8 (vestibular component) & associated functions

Back 77

-medial vestibular nucleus
-lateral vestibular nucleus (Deiter's)
-superior vestibular nucleus
-inferior vestibular nucleus
(^ vestibular= balance coordination)
-oculomotor nuclei- conscious perception of equilibrium & orientation

Front 78

Obj.
Nuclei of cranial nerve 7 & associated functions

Back 78

motor branch:
-facial motor nucelus: facial motor function to muscles of facial expression & (SVE) somatic motor to pharygneal arch muscles (stylohyoid, digastric post. belly, stapedius)
-abducens nucleus: motor to upper & lower face
intermediate branch:
-superior salvatory nucleus: (GVE) Stimulate secretions (lachrymal & salivary glands, mucousa)
-solitary nucleus: (SVA) taste

Front 79

Obj.
Nuclei of cranial nerve 6 & associated functions

Back 79

-oculomotor nuclei: conjugate eye movements