Cranial Nerves and their Nuclei

Question 1

If CN XII is lesioned, which side does the tongue stick out?

Answer 1

Towards side of lesion

Question 2

How to test CN XI function?

Answer 2

Ask patient to shrug shoulders, turn head against resistance. Weakness can result in torticollis

Question 3

What nuclei are involved with CN X?

Answer 3

nucleus ambiguous (motor to pharynx and soft palate and larynx)

dorsal motor nucleus (presynaptic parasympathetic fibers to smooth muscles of gut tube)

baraoreceptors in carotid sinus to monitor BP

taste (minor around epiglottis) and chemoreceptors in carotid body monitor blood O2 levels

Question 4

What do CN X lesions result in?

Answer 4

• lesion to nucleus ambiguus or vagus nerve itself = paralysis of muscles of larynx and pharynx, produces hoarseness or difficulty swallowing
• cortical supply to nuclei is bilateral - therefore unilateral lesions to CB fibers produce no noticeable effects

Question 5

What nuclei are involved with CN IX

Answer 5

secretomotor supply to parotid gland from INFERIOR SALVATORY NUCLEUS

sensory from taste, chemoreceptors in carotid body SOLITARY NUCLEUS

Question 6

Lesions in CN IX?

Answer 6

lesions at nucleus may have lack of gag reflex

Question 7

Lesion in CN VIII?

Answer 7

because of connections from vestibular nuclei to muscles of eye, lesions may produce nystagmus (jiggling eyes)

Question 8

CN VII lesion?

Answer 8

Bell’s palsy (lower motor neurons)
(cannot close eye, mouth droops, hyperacusis)

cortical lesions (typically not noticeable to forehead and eyes because of bilateral input) However, may produce paralysis to lower muscles (around mouth) because of strictly contralateral supply