Expansion
Lateral rectus CN VI, superior oblique CN IV, all others CN III
Mnemonic
LR6 SO4, all the rest are 3:
- LR6 - Lateral Rectus is supplied by cranial nerve VI, the abducens
- SO4 - Superior Oblique by cranial nerve IV, the trochlear
- All the rest are 3 - the remaining four muscles, plus levator palpebrae superioris, by cranial nerve III
The two exceptions are also the two with unusual actions: superior oblique depresses the adducted eye and intorts, and lateral rectus purely abducts.
The oblique muscles work opposite to their names: the superior oblique depresses and the inferior oblique elevates, because they pull from in front of the eye rather than behind it.
Expansion
- LR6 - Lateral rectus is supplied by CN VI
- SO4 - Superior oblique is supplied by CN IV
- AO3 - All other extraocular muscles are supplied by CN III