Advanced Hypoglossal Nerve Quiz

Q1. Which pattern most strongly indicates a right lower motor neuron hypoglossal lesion?

• Bilateral loss of tongue sensation
• Right tongue atrophy and fasciculations with deviation to the right
• Right tongue weakness with deviation to the left and no atrophy
• Left facial paralysis with normal tongue movement

Q2. Why does the tongue deviate toward the side of a peripheral CN XII lesion?

• The vagus nerve forces the tongue toward the lesion
• The injured styloglossus pulls the tongue toward the lesion
• The intact genioglossus pushes the protruded tongue toward the weak side
• Sensory loss causes reflex deviation

Q3. How does a typical unilateral corticobulbar lesion above the hypoglossal nucleus affect tongue protrusion?

• The tongue tends to deviate away from the cerebral lesion
• There is complete bilateral tongue paralysis
• The tongue develops immediate ipsilateral fasciculations
• The tongue always deviates toward the cerebral lesion

Q4. Which additional deficit may accompany CN XII palsy in a lesion involving the medial medulla?

• Bilateral blindness is typical
• Isolated hearing loss is expected
• Ipsilateral facial paralysis is always required
• Contralateral body weakness may accompany ipsilateral tongue weakness

Q5. Why can a lesion of the hypoglossal canal produce isolated tongue motor deficits?

• CN XII passes through its own dedicated hypoglossal canal
• The canal contains all trigeminal divisions
• The facial nerve exits through the same canal
• CN XII shares the canal only with CN IX and CN X

Q6. Which finding helps distinguish a distal CN XII lesion from a lesion of C1 fibers traveling with CN XII?

• Intrinsic and extrinsic tongue weakness indicates true CN XII involvement rather than isolated C1 hitchhiking fibers
• Loss of facial sensation indicates isolated C1 injury
• Pupillary dilation distinguishes the two
• Hearing loss indicates true CN XII injury

Q7. Which sequence correctly traces CN XII from its nucleus to the tongue?

• Hypoglossal nucleus to preolivary sulcus to hypoglossal canal to upper neck to superficial surface of hyoglossus to tongue
• Trigeminal motor nucleus to hypoglossal canal to facial canal to tongue
• Hypoglossal nucleus to jugular foramen to parotid gland to tongue
• Nucleus ambiguus to foramen ovale to infratemporal fossa to tongue

Q8. Why is palatoglossus considered an important exception when describing hypoglossal motor supply?

• It is an extrinsic tongue muscle supplied by the vagus rather than CN XII
• It has no motor innervation
• It is the only intrinsic tongue muscle supplied by CN V3
• It receives its motor supply from CN VII

Q9. Which combination best localizes a lesion to the hypoglossal nerve rather than the hypoglossal nucleus plus adjacent medial medulla?

• Ipsilateral tongue weakness with contralateral hemiparesis
• Ipsilateral tongue lower motor neuron signs without contralateral body deficits
• Bilateral gaze palsy with facial weakness
• Tongue weakness with contralateral loss of vibration and proprioception

Q10. Which statement best integrates hypoglossal nerve anatomy?

• CN XII is a medullary somatic motor nerve that exits through the hypoglossal canal and supplies nearly all tongue muscles while temporarily carrying C1 fibers
• CN XII is a branch of the vagus nerve that supplies palatoglossus only
• CN XII is a mixed sensory and motor nerve exiting through the jugular foramen
• CN XII carries taste from the anterior tongue and supplies salivary glands