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DR Medhat MRCP

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IV. Trochlear nerve :<br />

- The nucleus of this nerve lies in the lower part in the midbrain.<br />

- Passes in the cavernous sinus (below Cr3, & above ophthalmic division of Cr5)<br />

- It supplies superior oblique muscle which turns the eye downwards & inwards<br />

• Effect of lesion :<br />

ميقدرش ينزل السلم downwards. 1. Diplopia : only when the patient looks<br />

2. Limitation of eye movement on looking inwaeds & downwards.<br />

- Impairment of adduction in both eyes signifies bilateral internuclear<br />

ophthalmoplegia which is usually accompanied by nystagmus of the abducting eye<br />

→ indicates that the lesion is the medial longitudinal bundle in the brainstem<br />

سؤال مهم which connect III & VI crainial nerves<br />

- The main causes of internucular ophthalmoplegia are :<br />

1) Multiple sclerosis<br />

2) Brain stem stroke/tumor.<br />

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