Cranial Nerve Questions - p. 2
31. Which cranial nerve connects the brain to the gastrointestinal tract and plays a central role in communication along the gut–brain axis?
- A. olfactory nerve (CN I)
- B. trigeminal nerve (CN V)
- C. vagus nerve (CN X)
- D. hypoglossal nerve (CN XII)
Show Answer
Correct answer: C
The vagus nerve (CN X) sends and receives signals between the brain and much of the GI tract. Because it carries both sensory information from the gut to the brain and motor signals back to the gut, it is the main nerve involved in communication along the gut–brain axis.
32. Damage to the glossopharyngeal nerve (cranial nerve IX) would most likely be associated with which of the following?
- A. loss of taste on the anterior 2/3 of the tongue
- B. difficulty moving the tongue side to side
- C. loss of taste on the posterior 1/3 of the tongue
- D. facial paralysis on one side of the face
Show Answer
Correct answer: C
Damage to the glossopharyngeal nerve can cause a variety of symptoms, including a loss of taste on the posterior ⅓ of the tongue, trouble swallowing, and generally decreased sensation on the back of the tongue, the soft palate, and pharynx.
33. Marcus is hit in the forehead with a baseball and immediately feels sharp pain in that area. Which division of the trigeminal nerve carries this sensory information?
- A. ophthalmic division (V1)
- B. maxillary division (V2)
- C. mandibular division (V3)
- D. none of the above; it would be carried by the facial nerve
Show Answer
Correct answer: A
The trigeminal nerve is the main sensory nerve of the head. It has three divisions, the ophthalmic, maxillary, and mandibular divisions, which supply three different regions of the head and face. The forehead is supplied by the ophthalmic division of the trigeminal nerve.
34. A doctor lightly touches a patient's right cornea with a wisp of cotton. Her right eye blinks, but her left eye does not. What does this suggest?
- A. a deficit with the right trigeminal nerve
- B. a deficit with the right facial nerve
- C. a deficit with the left trigeminal nerve
- D. a deficit with the left facial nerve
Show Answer
Correct answer: D
The corneal reflex is used clinically to assess the trigeminal nerve (sensory/afferent limb) and the facial nerve (motor/efferent limb). Touching the right cornea should produce blinking in both eyes. Because the right eye blinks, the right trigeminal nerve and right facial nerve are intact. The absence of blinking in the left eye indicates a deficit in the left facial nerve.
35. Demetrius experiences a traumatic head injury. Afterward, his left eye is deviated medially at rest and he reports double vision (diplopia). He is unable to move his left eye laterally. Damage to which cranial nerve is most likely responsible?
- A. abducens nerve (CN VI)
- B. oculomotor nerve (CN III)
- C. trochlear nerve (CN IV)
- D. optic nerve (CN II)
Show Answer
Correct answer: A
The abducens nerve is a motor nerve responsible for moving the eye laterally toward the side of the head. Damage to the abducens nerve causes impairment in the ability of the eye the nerve supplies to to move laterally, and a condition called esotropia in which the eye that’s affected deviates medially. This also leads to diplopia, or double vision.
36. A patient presents with an upward deviation of the right eye and has adopted a compensatory head tilt to reduce double vision. Damage to which cranial nerve is the most likely cause of these symptoms?
- A. optic nerve (CN II)
- B. trochlear nerve (CN IV)
- C. trigeminal nerve (CN V)
- D. abducens nerve (CN VI)
Show Answer
Correct answer: B
Because the superior oblique muscle helps to move the eye downwards, when the trochlear nerve is damaged the eye tends to deviate upwards since there is no opposing force coming from the superior oblique. This can result in diplopia, or double-vision. Some patients will adopt a head tilt as a compensatory mechanism to better align the eyes and reduce the diplopia.
37. A physician shines a light into a patient’s left eye only. The left pupil constricts, but the right pupil does not. Based on these findings, which cranial nerve is most likely impaired?
- A. there is no obvious impairment
- B. the left optic nerve
- C. the right oculomotor nerve
- D. the right optic nerve
Show Answer
Correct answer: C
The pupillary light reflex is used to assess the function of the optic and oculomotor nerves and related structures. If light shined in the left eye causes only the left pupil to constrict, this indicates the sensory signal was received (since the left pupil constricted), but it may suggest a problem with the right oculomotor nerve (because the right pupil didn't constrict).
38. A patient presents with his left eye deviated down and laterally (to the side) and his left eyelid drooping. He reports that he can't move his left eye up or down. Which cranial nerve is most likely dysfunctional?
- A. CN II (optic nerve)
- B. CN III (oculomotor nerve)
- C. CN IV (trochlear nerve)
- D. CN VI (abducens nerve)
Show Answer
Correct answer: B
Damage to the oculomotor nerve often results in deviation of the affected eye to the side and downwards, impaired vertical and medial eye movements, and ptosis (drooping of the eyelid).
39. What is typically the main symptom of trigeminal neuralgia?
- A. Progressive facial muscle weakness
- B. Persistent numbness in the cheek and jaw
- C. Sudden, severe, stabbing facial pain
- D. Difficulty swallowing and speaking
Show Answer
Correct answer: C
Trigeminal neuralgia, also known as tic douloureux, is a disorder of cranial nerve V, the trigeminal nerve. The trigeminal nerve is the main sensory nerve for the face; it also controls motor functions of the jaw like biting and chewing. Trigeminal neuralgia is a pain disorder that causes sudden intense pain, typically on one side of the face.
40. A patient has damage to the facial nerve. Which of the following symptoms would you expect to observe?
- A. loss of sensation from one side of the face
- B. difficulty protruding the tongue
- C. difficulty swallowing
- D. paralysis of the muscles of facial expression on one side of the face
Show Answer
Correct answer: D
Facial nerve damage can cause a variety of symptoms, but the most recognizable of them is weakness and/or paralysis of the muscles of facial expression on the same side of the head that the damaged nerve supplies.
41. Which cranial nerve innervates four of the six extraocular muscles and is primarily responsible for moving the eye upward, downward, and medially?
- A. optic nerve (CN II)
- B. oculomotor nerve (CN III)
- C. trochlear nerve (CN IV)
- D. abducens nerve (CN VI)
Show Answer
Correct answer: B
The oculomotor nerve is responsible for supplying 4 of the 6 extraocular muscles: the medial rectus, which moves the eye towards the nose; the superior rectus, which moves the eye upwards; the inferior rectus, which moves the eye downwards; and the inferior oblique, which moves the eye up and out.
42. Although the trigeminal nerve (CN V) is the main sensory nerve of the head, it also provides motor innervation to muscles involved in:
- A. facial expression
- B. tongue movement
- C. eye movement
- D. mastication (chewing)
Show Answer
Correct answer: D
Although the trigeminal nerve is the main sensory nerve of the head, it also controls the muscles involved with chewing.
