Extraocular Muscle Innervation

The superior oblique extra ocular muscle is innervated by cranial nerve number four (Trochlear nerve),
 while the lateral rectus muscle is innervated by cranial nerve number six (Abducens nerve). The rest of the ocular muscles are innervated by cranial nerve three (oculomotor nerve). 
One easy way to remember this is to think of the fictional chemical formula (LR6SO4)