Today we continue ONWARD with the series on the Cranial Nerves. But we’re doing something a little different. Because last time we covered the Oculomotor Nerve, which innervates FOUR of the SIX muscles which control the eye, today we’re going to round out the eye (heh, round, eye, heh) and do the other TWO. But we’re going to have to go out of order. The order of the Cranial Nerves (with convenient mnemonic!) goes like this:
We’ve been through the Oh, Oh, Oh (cranial nerves I, II, and III), but the two cranial nerves that control motor movements of the rest of the eye are NOT IV and V. Instead, they are IV and VI, the Trochlear Nerve and the Abducens. And we’re going to cover them together, because each one is a motor nerve that moves exactly one muscle, and each one sends signals out from exactly one nucleus. Nice and relatively simple.
So here we go. And we’ll start out seeing where they peek out from the brain:
You can see the trochlear nerve poking out, all thin, just to either side of the top of that rounded trapezoid that is the basal pons, while the abducens comes out of the bottom of the basal pons.