QuestionSBA
QuestionChoice
Damage to the optic nerve (e.g. glaucoma) would present with more generalised visual loss or diplopia. As this man's double vision is only on looking down this makes optic nerve damage less likely.
10027774
d
Optic nerve (CN II)
QuestionChoice
The trochlear nerve innervates the superior oblique muscle which is responsible for depression of the eye. As this muscle is not working, there will be diplopia whilst looking down.
10027771
a
Trochlear nerve (CN IV)
QuestionChoice
The trigeminal nerve is not involved in eye movement so a palsy of the trigeminal nerve would not cause diplopia. The trigeminal nerve is instead involved in providing sensation to the face and innervating the muscles of mastication.
10027775
e
Trigeminal nerve (CN V)
QuestionChoice
The oculomotor nerve innervates most of the muscles of the eye. The presentation of a third nerve palsy is the action of the other extra-ocular muscles. The eye will be "down and out" due to the action of the superior oblique and lateral rectus.
10027772
b
Oculomotor never (CN III)
QuestionChoice
The abducens nerve innervates the lateral rectus muscle which is responsible for abduction of the eyes. This would present with diplopia when looking away from the midline as well as bumping into things on the affected side.
10027773
c
Abducens nerve (CN VI)
Concept
Chapter
2693
3970
Isolated cranial nerve palsies affecting the eye
Topic
141
Neurology
17952
A 67-year-old man presents after a fall down the stairs. Luckily, there are no obvious injuries at present. On further questioning, he mentions he has been struggling when coming down the stairs for a few weeks as he feels he can not see where he is going. As part of the examination, a full neurological assessment is carried out which shows difficulty looking down.

Which cranial nerve is likely affected?
a