QUESTION: 17

A neurologist is performing the neurological examination on a patient who recently suffered a head trauma. You note that, as part of the examination, she uses a cotton swab to touch the upper part of the auricle, the external auditory meatus, and the lobule. The external auditory meatus of the ear is innervated by which of the following?

vagus (tenth cranial) nerve
great auricular nerve
auriculotemporal nerve
greater occipital nerve
facial (seventh cranial) nerve

Answer(s): A

Explanation:

The vagus (tenth cranial) nerve innervates the external auditory meatus of the ear. The great auricular nerve (choice B) innervates the lobule of the auricle and the auriculotemporal nerve (choice C), the superior aspect of the auricle. In fact, a sensory test which includes these three parts of the ear tests the integrity of the trigeminal (fifth cranial) nerve by the auriculotemporal nerve, the vagus (tenth cranial) nerve by its branch innervating the auditory meatus, and spinal nerves C2-3 by their great auricular branch. The test thus covers the upper and lower medulla and the upper spinal cord. The greater occipital nerve (choice D) is a branch of the cervical plexus originating from C2 and innervates the scalp of the back of the head.
The facial (seventh cranial) nerve provides only motor innervation to the face and scalp areas.

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QUESTION: 18

A 48-year-old male patients is brought to the emergency room because of intense pain of the right face and neck with transient visual loss of the right eye. On examination, the patient has palsy of the oculomotor nerve on the right side with resulting diplopia, along with a right lateralized painful Horner syndrome. This constellation of signs is suggestive of a cervical carotid dissection, which is a separation of the arterial tunical intima from the subjacent tunica media. Which numbered structure in following figure, is the tunica intima?

Answer(s): D

Explanation:

Arrow 3 points to the tunica intima. The carotid artery is an elastic artery, which contains the following layers aside from the tunica intima: Tunica externa (arrow 1), and tunica media (arrow 5). In a carotid dissection, the tunica intima can elevate or separate from the tunica media with accompanying hemorrhage of the arterial wall. The most common clinical signs are ophthalmological manifestations including painful Horner syndrome, palsy of the oculomotor nerve, diplopia, and transient monocular visual loss. Arrow 2 points to a vasa vasorum, vessels which nourish the thick wall of the aorta. Arrow 4 points to the adipose tissue in the tunica externa.

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QUESTION: 19

The structure indicated by arrow 2 in following figure, is which of the following?

ethmoidal sinus
inferior nasal meatus
infratemporal fossa
maxillary sinus
sphenoidal sinus

Answer(s): A

Explanation:

This axial scan is at the level of the orbits as indicated by the insert at the bottom right and the eyeballs in the orbits. Arrow 2 points to the ethmoidal sinus located medial to the orbits. The sinus is divided into compartments by the air cells. The maxillary sinus (choice D) and the inferior nasal meatus (choice B) are located inferior to the level of this scan and are not seen. The sphenoidal sinus (choice E) is indicated by arrow 3 and the infratemporal fossa (choice C) by arrow 1.

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QUESTION: 20

A stroke resulting from obstruction of the structure indicated by arrow 1 in following figure, may result in ischemia in which of the following brain regions?

Broca's area in the left frontal lobe
cerebellum
medial aspect of the right frontal lobe
pons
Wernicke's area in the left frontal lobe

Answer(s): C

Explanation:

Arrow 1 points to the right internal carotid artery which supplies the anterior and middle cerebral arteries in the brain. The territory of the right anterior cerebral artery includes the rightmedial aspect of the frontal lobe, which will be affected by obstruction of the internal carotid artery. Broca's (choice A) and Wernicke's (choice E) areas are located in the majority of the population in the left cerebral hemisphere and are supplied by the left middle cerebral artery from the left internal carotid artery. They will not be affected in this case. The cerebellum (choice B) and pons (choice D) receive their blood supply from the basilar artery (arrow 2) which is formed from the vertebral arteries.

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