Chapter 10 : Trigeminal System (4)

Question 1

1. A 55-year-old patient with idiopathic trigeminal neuralgia reports sharp, stabbing pain in the upper lip and nose. Which branch of the trigeminal nerve is affected?
(A) Ophthalmic
(B) Maxillary
(C) Mandibular
(D) Lacrimal
(E) Corneal

Answer 1

1–B. The maxillary branch of the trigeminal nerve (CN V-2) innervates the upper lip and cheek, lower eyelid, anterior portion of the temple, paranasal sinuses, oral mucosa of the upper mouth, nose, pharynx, gums, teeth hard palate, soft palate, and cranial dura.

Question 2

2. What is the treatment drug of choice for the patient in question 1?
(A) Carbamazepine
(B) Lamotrigine
(C) Clonazepam
(D) Gabapentin
(E) Clobazam

Answer 2

2–A. Carbamazepine is the drug of choice for treatment of idiopathic trigeminal neuralgia. It,along with lamotrigine, clonazepam, gabapentin, and clobazam, is also used to treat seizure disorder

Question 3

3. The dorsal trigeminothalamic tract is a pathway for which type of sensation?
(A) Light touch
(B) Extreme pain
(C) Discriminative tactile
(D) Hot temperature
(E) Cold temperature

Answer 3

3–C. The dorsal trigeminothalamic tract subserves discriminative tactile and pressure sensation from the face and oral cavity via the GSA fibers of the trigeminal nerve (CN V). Pain, temperature, and light touch sensations are conveyed via the ventral trigeminothalamic tract.

Question 4

4. Which of the following muscles opens the jaw?
(A) Buccinator
(B) Temporalis
(C) Masseter
(D) Medial pterygoid
(E) Lateral pterygoid

Answer 4

4–E. The lateral pterygoid muscle is one of four muscles of mastication. Unlike the other muscles,
it opens the mouth by depressing the jaw. It also helps the medial pterygoid muscles in moving
the jaw from side to side. The temporalis, medial pterygoid, and masseter muscles work to close
the jaw. The muscles of mastication are innervated by the trigeminal motor nucleus (SVE).

Question 5

5. The auricle (pinna) of the external ear is innervated by which of the following nerves?
(A) V-3
(B) V-2
(C) V-1
(D) III
(E) VIII

Answer 5

5–A. The mandibular nerve, CN V-3, is a division of the trigeminal nerve (CN V) and innervates
the external ear, external auditory meatus and tympanic membrane, lower lip and chin, posterior
portion of the temple, teeth of the lower jaw, oral mucosa of the cheeks, floor of the mouth,
anterior two-thirds of the tongue, temporomandibular joint and cranial dura.

Question 6

6. An absent lacrimal reflex indicates problems with which two cranial nerves?
(A) V, VII
(B) III, VII
(C) VII, X
(D) II, V
(E) V, VIII

Answer 6

6–A. The lacrimal reflex involves the first branch of the trigeminal nerve, the ophthalmic nerve
(CN V-1), and the facial nerve (CN VII). The afferent limb is CN V-1, receiving impulses from the
cornea and conjunctiva. The efferent limb is CN-VII, transmitting impulses via the superior salivatory
nucleus, greater petrosal nerve, pterygopalatine ganglion, and the zygomatic and lacrimal
nerves to the lacrimal gland (see Figure 13-5).

Question 7

7. Destruction of which cranial nerve results in complete internal ophthalmoplegia?
(A) I
(B) II
(C) III
(D) IV
(E) V

Answer 7

7-E. Destruction of CN III results in complete internal ophthalmoplegia, which is paralysis of the
pupillary sphincter and ciliary muscle.