Cranial Nerve Functions Quiz: Match Nerve to Function

Updated

The 12 cranial nerves serve sensory, motor, and autonomic functions. Damage causes specific deficits, such as anosmia (I), ptosis/dilated pupil (III), facial paralysis (VII), or tongue deviation (XII).

This quiz tests your understanding of cranial nerve functions and the clinical signs of their lesions. It is designed for neuroscience students, medical trainees, or anyone reviewing neuroanatomy.

Before you start, recall that each cranial nerve has a specialized role: some are purely sensory (I, II, VIII), some purely motor (III, IV, VI, XI, XII), and others are mixed (V, VII, IX, X). Recognize the classic deficits caused by damage to each nerve.

Start the 15 questions

The questions

  1. Which cranial nerve is responsible for the sense of smell?

  2. Which cranial nerve transmits visual information from the retina to the brain?

  3. Which cranial nerve innervates the lateral rectus muscle, which abducts the eye?

  4. Which cranial nerve provides motor innervation to the muscles of facial expression?

  5. Which cranial nerve is responsible for both hearing and balance?

  6. Damage to the oculomotor nerve (CN III) classically causes which set of signs on the affected side?

  7. The trochlear nerve (CN IV) innervates which extraocular muscle?

  8. Loss of facial sensation and weakness of the muscles of mastication suggests damage to which cranial nerve?

  9. Which cranial nerve carries the afferent (sensory) limb of the gag reflex?

  10. Damage to the hypoglossal nerve (CN XII) causes the tongue to deviate toward which side when protruded?

  11. Parasympathetic fibers of the facial nerve (CN VII) are responsible for which function?

  12. Which cranial nerve carries the afferent limb of the corneal reflex?

  13. In the pupillary light reflex, the efferent pathway travels via which cranial nerve to constrict the pupil?

  14. Which cranial nerve innervates the sternocleidomastoid and trapezius muscles?

  15. Damage to the vagus nerve (CN X) most likely results in which symptom?

0 of 15 answered · 0 correct

Cheat sheet: key terms

Olfactory (CN I)Smell; damage causes anosmia.
Optic (CN II)Vision; damage causes visual field defects.
Oculomotor (CN III)Most eye movements and pupil constriction; damage causes ptosis and mydriasis.
Trigeminal (CN V)Facial sensation and mastication; damage causes sensory loss and jaw weakness.
Facial (CN VII)Facial expression, taste (anterior 2/3), lacrimation; damage causes Bell's palsy.
Vagus (CN X)Parasympathetic to organs, larynx/pharynx; damage causes hoarseness and dysphagia.
Hypoglossal (CN XII)Tongue movement; damage causes tongue deviation to lesion side.

Answers explained

Show all 15 answers
  1. Which cranial nerve is responsible for the sense of smell? Olfactory (CN I). The olfactory nerve carries sensory information from the nasal epithelium to the olfactory bulb; damage causes anosmia (loss of smell).
  2. Which cranial nerve transmits visual information from the retina to the brain? Optic (CN II). The optic nerve is the sensory nerve for vision; damage to it causes visual field defects or blindness.
  3. Which cranial nerve innervates the lateral rectus muscle, which abducts the eye? Abducens (CN VI). The abducens nerve controls the lateral rectus; damage causes inability to move the eye outward (abduction deficit).
  4. Which cranial nerve provides motor innervation to the muscles of facial expression? Facial (CN VII). The facial nerve innervates the muscles of facial expression; damage leads to facial paralysis (e.g., Bell's palsy).
  5. Which cranial nerve is responsible for both hearing and balance? Vestibulocochlear (CN VIII). The vestibulocochlear nerve has two divisions: cochlear (hearing) and vestibular (balance); damage causes deafness and/or vertigo.
  6. Damage to the oculomotor nerve (CN III) classically causes which set of signs on the affected side? Ptosis and dilated pupil. CN III controls the levator palpebrae (eyelid elevation) and pupillary constrictor; damage leads to drooping eyelid and enlarged pupil.
  7. The trochlear nerve (CN IV) innervates which extraocular muscle? Superior oblique. The trochlear nerve uniquely innervates the superior oblique muscle; damage causes vertical diplopia, especially when looking down and inward.
  8. Loss of facial sensation and weakness of the muscles of mastication suggests damage to which cranial nerve? Trigeminal (CN V). The trigeminal nerve provides sensory innervation to the face and motor innervation to the muscles of mastication (e.g., masseter).
  9. Which cranial nerve carries the afferent (sensory) limb of the gag reflex? Glossopharyngeal (CN IX). The glossopharyngeal nerve supplies sensation to the posterior pharynx; damage impairs the gag reflex.
  10. Damage to the hypoglossal nerve (CN XII) causes the tongue to deviate toward which side when protruded? Toward the side of the lesion. Unilateral hypoglossal weakness causes the tongue to point toward the affected side because the healthy muscle pushes it across the midline.
  11. Parasympathetic fibers of the facial nerve (CN VII) are responsible for which function? Tear production. The facial nerve, via the greater petrosal nerve, stimulates the lacrimal gland; damage can cause dry eye.
  12. Which cranial nerve carries the afferent limb of the corneal reflex? Trigeminal (CN V, ophthalmic division). The ophthalmic division of the trigeminal nerve senses corneal touch; loss of this reflex indicates trigeminal dysfunction.
  13. In the pupillary light reflex, the efferent pathway travels via which cranial nerve to constrict the pupil? Oculomotor (CN III). The oculomotor nerve carries parasympathetic fibers to the sphincter pupillae; damage causes a dilated, nonreactive pupil.
  14. Which cranial nerve innervates the sternocleidomastoid and trapezius muscles? Accessory (CN XI). The accessory nerve supplies these neck and shoulder muscles; damage causes weakness turning the head and shrugging the shoulder.
  15. Damage to the vagus nerve (CN X) most likely results in which symptom? Hoarseness and dysphagia. The vagus innervates laryngeal and pharyngeal muscles; damage causes hoarse voice and difficulty swallowing.

See it in 3D: open the interactive brain and click any region, or ask the AI coach anything you missed.