The<unk>  cranial<unk>  innervates the superior oblique muscle for each eye. The superior oblique muscle is one of the six extraocular muscles that allow movement of eye. Specifically, the superior oblique muscle primarily intorts the eye (such that the top of the eye rolls toward the nose), with secondary actions of depression (downgaze) and abduction (looking away from the nose). When this muscle's function is diminished due to a<unk>  cranial<unk>  (CN IV)<unk> , the affected eye will extort, deviate upward (hypertropia), and, to a smaller extent, drift inward.
Congenital fourth nerve palsy
Cranio-lenticulo-sutural dysplasia
Choroid plexus tumor
Morning glory disc anomaly
Choroid plexus papilloma
Athetoid cerebral palsy
Tonic tensor tympani syndrome
Choroid plexus cyst