Damage to nerve supplying Superior oblique causes diplopia in which direction? (AIPG 2011)
|A||Horizontal and downward|
|B||Vertical and downward|
|C||Horizontal and upward|
|D||Vertical and upward|
Trochlear or 4th cranial nerve produces diplopia due to paralysis of Superior oblique muscle which occurs in horizontal and downward gaze.
1. The abducens (VI) nucleus is located at the level of pons.
2. The nerve emerges from the ventral pontomedullary junction just lateral to the pyramid, passes through the prepontine CSF cistern and pierces the basal dura to enter Dorello's canal and then traverse the cavernous sinus.
3. Here the nerve is in direct relation to the internal carotid artery before it passes through the superior orbital fissure to the lateral rectus muscle.
4. The autonomic nervous system and integrity of the iris determine the resting size of the pupil.
5. The afferent limb of the pupillary reflex involves the optic nerve, bypassing the lateral geniculate nucleus to terminate in the pretectal nucleus. Interinincial neurons pass to both sides throught the branch to Inferior III nerve (Edinger-Westphal) nucleus.
6. The efferent limb involves the inferior division of the third nerve, the ciliary ganglion short ciliary nerves supply the sphinetin pupilar relays in
7. With sympathetic stimulation the pupils dilate and the upper and lower eyelids retract. With parasympathetic stimulation (the fibres of which travel with the third nerve) the opposite occurs
Pure horizontal diplopia usually results from involvement of cranial nerve VI. The symptoms are worse looking to the affected side.