Easiest Way to Remember the Cranial Nerves: Ohh Ohh Ohh! | Corporis

Easiest Way to Remember the Cranial Nerves: Ohh Ohh Ohh! | Corporis

Some Say Marry Money But My Brother Says Big
something Matters More… What was that last B…Big boots, no… big
books… no. Big brains, that’s it. Get your head out of the gutter, todau we’re learning
the cranial nerves. [intro] Welcome back to another anatomy video, my name is Patrick, and just like you I remember sitting in class, trying to
come up with a clever, usuually inappropriate way to remember these cranial nerves. But if I’m honest with myself, I never really
understood why I was learning them. I was just like “Ohh ohh ohh to touch and
feel…” and did the menomenics and passed the test So my friends, by the end of this video you’ll
have a couple mnemonics to help you out on the test, but more importantly you’ll
understand /why/ these nerves are so important. As always, here’s the big picture. As the name implies, the cranial nerves come off of
your brain and brain stem unlike the spinal nerves you’re probably familiar with. Some of them poke out the anterior of your
brain while some of them have branches that loop all the way down into your chest. And the majority of them are involved in vital
senses like sight and hearing, so as a clinician, there’s a good chance you’ll have to do
a cranial nerve exam at some point. Like when I worked in sports medicine, we’d
always do a cranial nerve exam as part of our concussion assessments. So let’s get you familiarized here. Here’s the lateral view of your brain. This is the front or anterior, this is the
back or posterior. But this doesn’t give us a super clear picture
of the anatomy of interest, so we flip the skull side down and get a bottoms-up view. And now that we can see them, we assign them
Roman numerals based on their position from anterior to posterior. We’ll go through each nerve’s name and
function, but /now/ we can get our front to back, logical
numbering and ordering done. Okay, throughout this explanation, remember
that anatomists are terrible at naming things. Most of the time, the name is gonna be a giveaway
for the function of the nerve itself. The second thing is that some of these are
exclusively sensory, exclusively motor nerves, or both. So I’ll keep a running abbreviation over
here with the letter you’ll use for the naming acronym and whether it’s a sensory
nerve, motor, or both. Cranial nerve number 1, again going anterior
to posterior is the olfactory nerve and it’s responsible for the sense of smell. And look at it, look at this thing. It /looks/ like it’s supposed to go down
your nose, right? It’s double true when you see where those
big olfactory bulbs land in your skull. They go right on top of your nose where they
shoot a bunch of smaller nerves down into the nose that then pick up on those odorants. If you had to test this clinically, obviously
you’re gonna have someone smell something nice and familiar. Hot coffee usually works since everyone knows
what it smells like and it’s not gonna give anyone a headache. Cranial nerve number 2 is the optic nerve,
and it’s responsible for your sense of sight. Unfortunately when you’re studying that
inferior to superior view, that illustration doesn’t do this nerve justice. Look, your eyes are incredibly important and
deal when it comes to dealing with a lot of incoming information, right? So it totally makes sense that they’d have
a big thick nerve that connects the sensory receptors of the eye directly to the
brain. On that illustration, that little nub of a
nerve doesn’t look as important as what’s really happening. But with the eyeballs still attached, the
optic nerve finally looks like a big important nerve that transmits sight back to the brain. You can actually see the optic nerve if you
look longingly into the eyes of your patient, shine a bright light in there and find that
spot at the back of their eye. You’re looking at their optic nerves. The optic nerve is exclusively a sensory nerve
— the next few will be motor nerves for the eye. Cranial nerve 3 is the big eyeball mover,
the oculomotor nerve. And it’s responsible for /most/
of the movement of the eye. Muscles that make the eye look up, down, and
in and even raise the eyelid and constrict the pupil. But that leaves a couple of movements out. That’s where cranial nerves 4 and 6 come
in. The trochlear nerve, cranial nerve 4 handles
this super specific muscle called the superior oblique muscle, this dude right here. Trochlea comes from the Latin root for “pulley”
and when you look at this muscle, it acts totally like a pulley. Now, assuming you’re not a total etymology
dork, “trochlea” isn’t gonna come as easy as the oculomotor nerve, so here’s
how I remember it. When you test this nerve, you’d have the
patient rotate their eye downward and side to side. Like they’re looking down at a track, which
is the closest thing you’re gonna get to trochlear. That’s right, come to this channel for anatomy
topics and stay for the terrible memory devices. Now, to make things more complicated, the
oculomotor nerve only innervates one of side to side eye movers, the medial rectus muscles. So cranial nerve 6, the abducens nerve innervates
the /lateral/ rectus muscles. So if you’re already good with your terminology
of motion, you know that abduction of a joint is when you lift a limb out to the side. Obviously, that doesn’t happen with your
eyes, so I remember this one because of the overlap with abduction and lateral movement. On a clinical test though, most clinicians
will do the “follow my finger with your eyes” test to take care of cranial nerves
3, 4, and 6 at the same time. Coming back to Cranial nerve number 5, it’s
our first double dipper. It’s both sensory and motor. And /that’s/ because this guy, the trigeminal
nerve is actually three nerves, hence tri-geminal. The first branch is the ophthalmic nerve which
is the sensory nerve for the front top part of your face, the maxillary nerve which senses
everything from your upper palate, upper lip, and nasal cavity. Finally is the mandibular nerve, the
biggest branch of the three which innervates the mandible or the jaw. The motor part of this nerve comes from the
mandibular branch. If you have someone bite down on something
like a tongue compressor, their masseter and temporalis muscles will flex, which is usually
your test for that. So because your trigeminal nerve splits into
multiple branches and does a couple of jobs, it counts as both sensory and motor. Cranial nerve 7 is a doozie, it’s the facial
nerve and it’s another big branching nerve root. Now, our trigeminal nerve already took care
of a couple of motor functions around the face, but any complex facial expressions are made by muscles innervated by the facial nerve. But check this out, cranial
nerve 7 is a Both. We just heard about its motor functions, but
its sensory innervation is so frustrating I hate it. It’s responsible for taste only on the anterior
two-thirds of the tongue. And because of that, you have to remember
it as a Both. Cranial nerve 8 is the vestibulocochlear and
it’s responsible for your sense of hearing, which totally makes sense. We’re all the way down at nerve number 8
by now, so that nerve root is close to the ear. Cranial nerve number 8 is exclusively
a sensory nerve which makes sense — unlike dogs, humans don’t need to move their ears,
so we don’t have a ton of musculature around them to do that movement. There /are/ some very tiny muscles within
and around the ear, but they’re innervated by other nerves like the facial nerve. Couple of ways to remember this one. I recommend getting your lab mate, look directly
at their ear, lean in and whisper vestibulocochlear. Then they slap you in the face and the ringing
in your ears will be an ever present reminder that vestibulocochlear is responsible for
hearing. Cranial nerve number nine is the glossopharyngeal
nerve, which takes care of sensation for the back third of the tongue through some of the
oropharynx /and/ motor innervation of one specific muscle. There was a lot there, so let’s break it
down. Anytime you see that root glosso think tongue. Easy to remember since the tongue is covered
in saliva, so it’s glossy looking. The rest of the area innervated by the glossopharyngeal
is the pharyngeal part. Students trip up thinking that the pharynx
is like way down your neck, but it’s actually right below your tongue. It’s what connects your mouth and nasal
cavity to your tongue. Now this thing also controls one tiny muscle,
the stylopharyngeus muscle — this dude right here. Its called that cuz it connects the styloid
process near your ear down to this super wide area in your throat. Another tiny motor function, but it still
qualifies cranial nerve 9 as a both. Next up is the Vagus nerve, or number 10 — and
it’s the absolute superstar of the cranial nerves since it takes care of some like, life
or death oper ations. The Vagus nerve is the main nerve of the parasympathetic
nervous system. And if you’ve never heard that word before,
go check out my video on it right there. Quick oversimplified answer though: the parasympathetic
nervous system calms down a lot of processes while the sympathetic nervous system excites
them. So if you wanted your heart rate to speed
up, that’s sympathetic, if you wanted it to come back down, that’s parasympathetic,
and where the vagus nerve comes through. Vagus nerve is a long boi and has a bunch
of different branches, some dipping down through the diaphragm and into the stomach. Either way, it’s a big sensory interface
between organs like the lungs and stomach back up to the brain, but it also helps slow
down heart rate. The right branch of the vagus nerve partially
innervates the sinoatrial node, or SA node, in your heart. This is your major built in pacemaker that
keeps your heart pumping around 60 beats per minute. Cranial nerve eleven is the accessory nerve
and it’s the motor innervation for your upper traps and sternocleidomastoid. I remember this one because you take your
accessories like your purse or backpack, throw it over your shoulder and have to use your
accessory nerve to adjust it. Cranial nerve 12 is the hypoglossal nerve,
and since you have a beautiful mind you remember that glosso- means tongue, you’re already
thinking this must be the motor control of the tongue. So that’s everything from up down and side
to side, which you could use to make an H and remember hypoglossal. Now, very importantly, there /is/ a little
controversy on whether we’re finished there or not. While I was never taught this in school, enough
of the sources I read mentioned Cranial nerve 0, the terminal nerve. It’s this little bundle of nerves near,
but not attached to, the olfactory nerve. And if we’re comparing it to the terminal
nerve in other animals, it’s the nerve that would let us sniff out pheromones. These are chemicals that, in other animals
help regulate sexual behavior but in humans are almost certainly not a thing. But it might have a role in gonadotropin releasing
hormone regulation, so it’s worth knowing. Look, you’re probably not gonna get tested
on this one and you’re not gonna use it during a clinical exam. Either way, it’s a fun fact. So that’s all 12 or 13 cranial nerves, depending
on if we’re counting nerve zero. To help you remember them, you have nearly
infinite mnemonics to use. My undergrad professor insisted we use “On
old Olympic towering tops, a French and German viewed some hops” which … That worked for his brain, but never stuck
in mine. Plus, some of the memory devices use slightly
different name variations. Like my professor called the accessory nerve
the spinal-accessory nerve, which changes the acronym So I recommend reading a bunch of them and
figuring out which one genuinely sticks better for you. Some are family friendly, some are so dirty
they make me want to clean my eyeballs with bleach. I’ll link to the Wikipedia dedicated to
cranial nerve mnemonics down in the dooblydoo, but if you’ve got a favorite, write it in
the comments and we’ll upvote our favorites. Pro tip, you’ll probably know which day
your cranial nerves test is going to be on ahead of time, so when you go into your test
with your mnemonic locked and loaded in your brain, write it out in the margins so
you can come back to it and not freak out when you’re mid way through the test and
under pressure. A lot of these cranial nerves are the input
point for four of your five senses, so I recommend checking my nervous system playlist here if
you want a deep dive into how those senses work. A big thank you goes out to my Patrons Diana
and Jessica for making these videos happen. If you want to join them, click the link there. Otherwise you can support the channel for
free by subscribing and liking the video. Have fun, be good. Thanks for watching.

5 Replies to “Easiest Way to Remember the Cranial Nerves: Ohh Ohh Ohh! | Corporis”

  1. what's with all the long 'n weird names, its more confusing than the roads of vagus
    i feel so sympathetic towards people learning this

    e e e e e

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