Cranial Nerves

Question 1

trigeminal (V) innervates

deficits

Answer 1

• dura
• entire 1/2 of face including cornea, oral cavity and nasal mucosa (ophthalmic, maxillary, and mandibular divisions of the nerve)

ipsilateral decreased/impaired sensation

Question 2

facial (VII) innervates

deficits

Answer 2

small piece form behind the ear

ipsilateral decreased/impaired sensation

Question 3

glossopharyngeal (IX) innervates

deficits

Answer 3

• back of tongue
• upper pharynx

ipsilateral decreased/impaired sensation

Question 4

vagus (X) innervates

deficits

Answer 4

• lower pharynx
• layrnx
• esophagus

ipsilateral decreased/impaired sensation

Question 5

deficits associated with lesion in pons - chief sensory nucleus (of trigeminal)

Answer 5

decreased/impaired touch sensation throughout ½ of face, behind ear, all oral cavity, pharynx, larynx, and esophagus
ipsilateral deficits

Question 6

deficits associated with lesion in pons - ventral trigeminothalamic tract

Answer 6

decreased/impaired pain and temperature sensation throughout ½ of face, behind ear, all oral cavity, pharynx, larynx, esophagus
contralateral deficits (crossing occurs lower down)

Question 7

deficits associated with lesion in medulla - spinal trigeminal nuclei and tract

Answer 7

decreased/impaired pain and temperature sensation throughout ½ of face, behind ear, all oral cavity, pharynx, larynx, and esophagus
ipsilateral deficits
lesion in medulla ONLY affects nuclei (not crossing pain/temp fibers)

Question 8

deficits associated with lesion in sensory ascending pathway

Answer 8

decreased/impaired touch AND pain and temperature sensation throughout ½ of face, behind ear, all oral cavity, pharynx, larynx, and esophagus
contralateral deficits

Question 9

2 cranial nerves involved with taste

Answer 9

Facial (CN VII): anterior 2/3 of tongue and soft palate

Glossopharyngeal (CN IX): posterior 1/3 of tongue

Question 10

structures and general path for taste sensation from the nerve to the cortex

Answer 10

axons from CN VII and IX terminate in the gustatory nucleus which is the rostral portion of the nucleus of the solitary tract
this is in the pons
axons from this nucleus will synapse on cells in the VPM of the thalamus
from there, axons go through the internal capsule to the cortical area for taste in the parietal lobe (postcentral gyrus).
note: fibers also project from the gustatory nucleus to the hypothalamus and limbic system for autonomic and emotional responses to taste

Question 11

why taste is seldom affected by unilateral lesions

Answer 11

because taste is communicated bilaterally
this is more or less the same reason you are not likely to have clear cut hearing deficits from lesions in the auditory system if they occur rostral to the superior olivary nucleus (to throwback to the previous unit)

Question 12

which 2 nerves are involved in visceral sensation

Answer 12

glossopharyngeal and vagus

Question 13

type of info glossopharyngeal receives

Answer 13

oxygen tension and BP from carotid sinus and carotid body

Question 14

type of info vagal receives

Answer 14

oxygen tension and BP from in the aortic arch and in the aortic bodies and all sensation from sensory receptors in the trachea, bronchi, lungs, heart, stomach and intestines

Question 15

what structures receive visceral sensory info

Answer 15

reticular formation in medulla and pons - for cardiovascular and respiratory control

nucleus of the solitary tract (portion in medulla) - cardiovascular control and other autonomic functions

hypothalamus - to regulate autonomic nervous system

cortex - for conscious awareness of some of these sensations

Question 16

why visceral sensation is seldom affected by unilateral lesions

Answer 16

this is because visceral sensation, like taste and hearing, is communicated bilaterally

Question 17

which 4 cranial nerves are involved in parasympathetic autonomic functions

Answer 17

Oculomotor (CN III) - constriction of the pupil and focusing on a near object

Facial (CN VII) - salivation and lacrimation

Glossopharyngeal (CN IX) - parotid gland for salivation

Vagus (CNX) - parasympathetic cardiac and visceral functions (heart rate, BP, breathing, etc)

Question 18

location and deficits of lesion in automatic nucleus - Edinger Westphal nuclei in the midbrain

Answer 18

CN III
ipsilateral

Lesion in the midbrain or the nerve: results in impaire constriction of the pupil and decreased ability to focus on a near object

Question 19

location and deficits of lesion in automatic nucleus - Lacrimal and superior salivatory nuclei in the pons

Answer 19

CN VII
ipsilateral

Lesion in the pons or the nerve: results in decreased lacrimation and decreased salivation

Question 20

location and deficits of lesion in automatic nucleus - Inferior salivatory nuclei in The open medulla

Answer 20

CN IX
ipsilateral

Lesion in the open medulla or the nerve: results in decreased salivation

Question 21

location and deficits of lesion in automatic nucleus - Dorsal nuclei of the vagal nerve in the open and closed medulla

Answer 21

CN X
ipsilateral

Lesion in the open or closed medulla or the nerve: may result in
cardiac arrhythmias, constipation, urinary incontinence

Question 22

s/s lesion in oculomotor nerve/nuclei

Answer 22

LMN signs and symptoms in all muscles supplied - this does NOT include lateral rectus or superior oblique
lateral deviation of ipsilateral eye
can’t track medially
ptosis
diplopia
all reflexive movement of that eye to sound, light, etc. are lost

Question 23

s/s lesion in trochlear nerve/nuclei

Answer 23

diplopia when looking down and in

LMN signs and symptoms in superior oblique

Question 24

s/s lesion in trigeminal nerve/motor nuclei

Answer 24

LMN signs and symptoms in muscles of mastication, tensor tympani, mylohyoid, ant. digastric
decreased sound reflex

Question 25

s/s lesion in abducens nerve/nuclei

Answer 25

LMN signs and symptoms in lateral rectus diplopia ipsilateral eye is deviated medially reflexive eye movements to all stimuli lost

Question 26

s/s lesion in facial nerve/nuclei

Answer 26

LMN signs and symptoms in all muscles of facial expression, platysma, stylohyoid, post. digastric, stapedius inability to close eye weakness evident in entire side of face (upper and lower) LMN dysarthria drooling loss of blink reflex to all stimuli decreased sound reflex – sounds perceived as louder

Question 27

s/s lesion in glossopharyngeal nerve/nucleus ambiguus

Answer 27

LMN signs and symptoms in stylopharyngeus muscle dysphagia dysarthria gag reflex is impaired

Question 28

s/s lesion in vagus nerve/nucleus ambiguus

Answer 28

``` LMN signs and symptoms in muscles of pharynx, soft palate, larynx, esophagus dysphagia dysarthria hoarse Voice gag reflex is impaired ```

Question 29

s/s lesion in spinal accessory/cervical spinal cord ventral horn

Answer 29

LMN signs and symptoms in sternocleidomastoid, trapezius | Hypoglossal Nerve/Nuclei

Question 30

s/s lesion in hypoglossal nerve/nuclei

Answer 30

LMN signs and symptoms in muscles of the tongue LMN dysarthria dysphagia difficulty chewing and sucking tongue deviates ipsilateral to lesion (toward weakness)

Question 31

corticobulbar tracts lesions in CNs

Answer 31

CN V: descending bilateral corticobulbar fibers for voluntary movement CN VII: crossed corticobulbar fibers to alpha motor neurons contacting the lower facial muscles (crossing in the pons) and bilateral corticobulbar fibers to alpha motor neurons that innervate the muscles in the upper face CN IX and X: descending bilateral corticobulbar fibers for voluntary movement CN XII: crossed corticobulbar fibers (crossing in medulla)

Question 32

Lesions in Corticobulbar Pathway ABOVE the Pons

Answer 32

lower face: UMN signs and symptoms on contralateral side tongue: UMN signs and symptoms, tongue deviates toward weakness, dysarthria upper face, pharynx, larynx – NO UMN s/s = b/c BILATERAL, also no dysphagia all reflexes from nuclei in the pons and medulla are still intact reflexes in the midbrain are only affected if lesion is in midbrain

Question 33

Lesion in Corticobulbar Pathway IN the Pons

Answer 33

no UMN problems in upper or lower face tongue: contralateral UMN signs and symptoms, tongue deviates toward weakness, dyarthria pharynx, larynx, etc. - no UMN s/s = b/c BILATERAL, also no dysphagia all reflexes from nuclei in the midbrain and medulla are intact reflexes in the pons related to function of CN nuclei are lost decreased sound reflex – perceive things louder reflexive eye movements to stimuli lost loss of blink reflex to all stimuli

Question 34

lesion in medulla

Answer 34

no UMN deficits in face or tongue

Question 35

pupillary light reflex

Answer 35

afferents travel from optic nerve to Edinger Westphal nucleus in midbrain bilaterally efferents travel from both nuclei through CN III to constrict bilateral pupils direct response = constriction in ipsilateral eye consensual response = constriction in contralateral eye

Question 36

lesions in pupillary light reflex

Answer 36

lesion in one optic nerve neither eye can restrict in response to light that shines in that eye lesion in one EW nucleus that eye cannot constrict no matter which eye the light is in the other eye has intact pupillary light reflex to light that shines in either eye

Question 37

which structures are involved in the accommodation reflex

Answer 37

necessary to focus your eyes on near objects lesion in EW nucleus or CN III will impair this ability afferents travel from occipital visual cortex to bilateral EW and CN III motor nuclei efferents exit brainstem in CN III to medially converge eyes and increase lens thickness response produces medial deviation of both eyes - innervates medial rectus through motor nuclei changes lens shape to focus on the object (through EW)

Question 38

frontal eye fields

Answer 38

cells in frontal eye fields send axons down through internal capsule axons synapse on cells in superior colliculus of midbrain cross midline and travel in tectobulbar tract to pontine paramedian reticular formation in pons right frontal eye field activates the eyes to look to the left left frontal eye field activates the eyes to look to the right

Question 39

lesions in frontal eye fields

Answer 39

eyes deviate toward side of lesion eyes deviate away from side of body that is paralyzed due to involvement of the primary motor cortex pt unable to gaze voluntarily towards paralyzed extremities

Question 40

pontine paramedian reticular formation

Answer 40

center for coordinating lateral gaze located in the pons coordinates medial rectus of one eye with lateral rectus of other through medial longitudinal fasciculus coordinates: excitation and inhibition of ipsilateral abducens excitation and inhibition of contralateral oculomotor nuclei right PPRF will coordinates eyes to look to the right left PPRF will coordinate eyes to look to the left

Question 41

lesions in pontine paramedian reticular formation

Answer 41

eyes deviate away from lesion | eyes deviate toward side of body paralysis (damaged corticospinal)