QuestionSBA
QuestionChoice
This is incorrect. The abducens nerve (CN VI) innervates the lateral rectus muscle. Patients with sixth nerve palsy present with diplopia that is worse in the horizontal plane.
10025853
d
CN VI
QuestionChoice
This is incorrect, the olfactory nerve (CN I) is responsible for smell. Patients with damage to this cranial nerve may experience a change or lack of their sense of smell.
10025854
e
CN I
QuestionChoice
This is incorrect. The trochlear nerve (CN IV) controls the superior oblique muscle. Damage to this cranial nerve presents with diplopia that is worse in the vertical plane, classically experienced when reading or going downstairs.
10025852
c
CN IV
QuestionChoice
Correct - this presentation is consistent with a third nerve palsy, caused by damage to the oculomotor nerve (CN III). CN III innervates most of the ocular muscles, except the superior oblique and lateral rectus muscles which are innervated by CN IV and CN VI respectively. In third nerve palsy, the superior oblique and lateral rectus muscles are the only functioning ocular muscles. Their unopposed activity pulls the eye into a characteristic 'down and out' resting position of the eye.
10025850
a
CN III
QuestionChoice
This is incorrect. The optic nerve (CN II) is responsible for vision. A CN II lesion would present with visual loss, rather than problems with eye movements.
10025851
b
CN II
Concept
Chapter
2693
3970
Isolated cranial nerve palsies affecting the eye
Topic
141
Neurology
17568
A 60 year old man presents to A&E after his sister notices that the appearance of his eyes has changed. The patient also notes some double vision and pain behind the right eye since waking up that morning. On examination, the patient's right eye is fixed in a downward, lateral position. There is also ptosis and fixed pupil dilatation. His visual acuity is intact in both eyes. There is no sensory loss or weakness throughout the rest of his body.

Which of the following cranial nerves is most likely implicated in the patient's presentation?
a