Advanced Hypoglossal Nerve Quiz

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

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

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

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

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
• The tongue always deviates toward the cerebral lesion
• There is complete bilateral tongue paralysis
• The tongue develops immediate ipsilateral fasciculations

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

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

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

• The facial nerve exits through the same canal
• The canal contains all trigeminal divisions
• CN XII passes through its own dedicated hypoglossal 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?

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

Q7. Which sequence correctly traces CN XII from its nucleus to the 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
• Hypoglossal nucleus to preolivary sulcus to hypoglossal canal to upper neck to superficial surface of hyoglossus to tongue

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

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

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

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

Q10. Which statement best integrates hypoglossal nerve anatomy?

• CN XII is a branch of the vagus nerve that supplies palatoglossus only
• CN XII carries taste from the anterior tongue and supplies salivary glands
• 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 mixed sensory and motor nerve exiting through the jugular foramen