Pons

Question 1

parts of the pons

Answer 1

tegmentum

basis pontis

Question 2

tegmentum

• what is it?
• location

Answer 2

portion of gray matter containing cranial nerve nuclei and ascending and descending tracts
lies between fourth ventricle and more ventrally located basis pontis or ventral pons

Question 3

basis pontis

• contains
• marked by…

Answer 3

ventral portion containing pontine nuclei and crossing pontine fibers running transversely
marked by large fascicles of fibers containing corticospinal, corticobulbar and corticopontine axons

Question 4

crossing pontine fibers in the basis pontis that run transversely become the…

Answer 4

middle cerebellar peduncle

Question 5

corticospinal, corticobulbar, and corticopontine axons in the basis pontis are running with what direction

Answer 5

caudal

Question 6

cerebellar peduncles

• how many?
• what are their names
• can all be seen at the _____ level

Answer 6

inferior
middle
superior
can be seen at the pontine level

Question 7

cerebellar peduncles

-function

Answer 7

inferior and middle
-allow cerebellar afferents to enter the cerebellum
superior
-allow cerebellar efferents to exit the cerebellum

Question 8

CNs associated with the pons

Answer 8

5-8

Question 9

CN VIII

-which division are we concerned with in relation to the pons

Answer 9

cochlear division

Question 10

CN VIII cochlear division

-function

Answer 10

relay of auditory information from the cochlea

Question 11

auditory information is distributed in what fashion?

Answer 11

bilaterally through brain stem and cortical auditory areas

Question 12

unilateral lesions of CNS auditory structures results in…

Answer 12

does not result in unilateral deafness

Question 13

in relation to CN VIII

-what must be damaged to result in ipsilateral deafness

Answer 13

both cochlear nuclei

Question 14

how is the cochlear division of CN VIII organized

Answer 14

tonotopically

-like topographic, but with sounds instead of body parts

Question 15

CN VIII cochlear division

• where does the information go?
• what information is sent?

Answer 15

cerebral cortex for perception of spoken word and sound

-primary auditory cortex

Question 16

primary auditory cortex location

Answer 16

superior surface of superior temporal gyrus

• within lateral sulcus
• Brodmann’s areas 21 and 42
• Transverse Temporal Gyri of Heschl

Question 17

function of cross-communication between sides of CN VIII cochlear division nuclei before arriving at cortex

Answer 17

supports the ability to localize sound to one side

Question 18

cochlear nerve

-consists of…

Answer 18

consists of axons or central process of neurons bringing afferent information from the inner ear

Question 19

cochlear nerve

• enters brainstem at…
• where does it go after this?

Answer 19

enters brainstem at cerebellopontine angle

birfurcates to synapse in both dorsal and ventral cochlear nuclei

Question 20

cochlear nerve nuclei location

Answer 20

superficial
located in rostral (open) medulla
-adjacent to base of inferior cerebellar peduncle and alongside the lateral aperture of the 4th ventricle

Question 21

CN VIII cochlear division

-synapses that occur after the cochlear nuclei

Answer 21

dorsal and ventral cochlear nuclei
superior olivary nucleus
lateral lemniscus (bilateral pathway for sound localization)
nucleus of inferior colliculus
brachium of inferior colliculus
medial geniculate nucleus
primary auditory cortex

Question 22

protective auditory reflexes

Answer 22

inferior colliculus > superior colliculus > tectospinal tract = reflex turning fo head to sound

Question 23

protective auditory reflexes

• function
• how does it accomplish this?

Answer 23

important for protection against loud noise
superior olivary nucleus projects to CN VII - stapedius muscle
-dampening of noise at the stapes
superior olivary nucleus also projects to CN V - tensor tympani muscle
-dampening of noise at the malleus

Question 24

acoustic neuroma

• what
• where
• malignant or benign?
• where does it begin?

Answer 24

tumor growing in the cerebellopontine angle

usually benign and beginning on the VIIIth nerve

Question 25

acoustic neuroma | -S/S

Answer 25

vestibular component -irritative lesion; changes in perception of head position - spinning sensation, vertigo tinnitus (ringing of the ears) - irritative lesion

Question 26

CN V | -function

Answer 26

general sensation of the face and head area | motor output to the muscles of mastication

Question 27

CN V | -sensory parts carry same modalities as what other systems

Answer 27

dorsal column system | spinothalamic tracts

Question 28

CN V carries general somatosensation for...

Answer 28

anterior 2/3 of the face

Question 29

CN V divisions

Answer 29

``` V1 -ophthalmic division; above the eye V2 -maxillary division; below the eye, above the mouth V3 -mandibular division; jaw ```

Question 30

CN V LMNs that innervate the muscles of mastication have their cell body in the...

Answer 30

motor nucleus of V

Question 31

CN V motor component also innervates...

Answer 31

tensor tympani nerve to mylohyoid -mylohyoid -anterior digastric

Question 32

CN VII | -LMNs innervate...

Answer 32

ipsilateral - muscles of facial expression - platysma - stapedius

Question 33

CN VII LMNs | -axons location

Answer 33

travel around the abducens nucleus to form the facial colliculus (bump on the floor of the 4th ventricle)

Question 34

CN VII | -where does it exit the pons?

Answer 34

exits at anterolateral part of tegmentum of lower pons

Question 35

CN VII | -which part of the face (upper or lower) receives bilateral UMN control?

Answer 35

upper

Question 36

CN VII | -the LMNs that innervate the lower part of the face receive UMN input from the _____ hemisphere

Answer 36

contralateral

Question 37

CN VII preganglionic parasympathetic neurons | -location

Answer 37

reticular formation in the caudal pons

Question 38

CN VII preganglionic parasympathetic neurons - functions - -specific part responsible for each function

Answer 38

tear production -postganglionic cell bodies in pterygopalatine ganglion (lacrimal gland) salivation -postganglionic cell bodies in submandibular ganglia (submandibular and sublingual glands)

Question 39

CN VII | -what sensory function does it perform?

Answer 39

taste

Question 40

CN VII LMN lesion results in what disorder

Answer 40

Bell's Palsy

Question 41

UMN or Central Facial Palsy | -where does the deficit occur?

Answer 41

contralateral lower face | -upper face has bilateral UMN innervation

Question 42

Sx of facial nerve lesions

Answer 42

LMN deficit of ipsilateral face dry cornea; ulcerated cornea loss of taste over ipsilateral anterior 2/3 of tongue inability to produce saliva hyperacusis - stapedius can't dampen sound

Question 43

corneal blink reflex is a combination of functions by which CNs

Answer 43

trigeminal | facial

Question 44

blink reflex - what is it - what are the components of the reflex?

Answer 44

``` touch the cornea and both eyes close direct reflex -closure of the touched eye indirect or consensual response -closure of the untouched eye ```

Question 45

circuits of blink reflex | -what are the components

Answer 45

``` receptor afferent limb interneurons direct reflex efferent limb indirect reflex efferent limb ```

Question 46

blink reflex receptor

Answer 46

free nerve ending in cornea (peripheral process of sensory neuron in the ophthalmic division of CN V)

Question 47

how do you elicit a response from the blink reflex receptor?

Answer 47

with cotton wisp

Question 48

blink reflex afferent limb | -where does the central process end?

Answer 48

central process ends in main sensory nucleus of V

Question 49

blink reflex interneurons - location - project to...

Answer 49

in main sensory nucleus of V | project directly to ipsilateral facial motor nucleus and to RF interneurons

Question 50

direct blink reflex efferent limb

Answer 50

ipsilateral facial motor nucleus to orbicularis oculi

Question 51

indirect blink reflex efferent limb

Answer 51

RF interneurons project to contralateral facial motor nucleus to activate contralateral orbicularis oculi