the cranial nerves are similar to your segmental nerves in that they have multiple modalities
and they have specific targets but the cranial nerves are all going to innervate structures in
your head and your neck they are motor sensory and they carry autonomics what's a little bit
different about the cranial nerves is that they can be segregated in that they may only carry
one modality and not multiple modalities and so here on our rubber brain stem we can see almost
all of the cranial nerves we can see crane well we can't see cranial nerve one because that's
olfactory and it doesn't attach to our brainstem so it's not on our brainstem model but we can see
2 3 4 5 6 7 8 9 10 11 and 12 and again they are going to innervate structures within the head and
neck they can be sensory motor or both and some of them will even carry an autonomic component
so here are the cranial nerves olfactory optic oculomotor trochlear trigeminal abducens facial
vestibulocochlear glossopharyngeal vagus spinal accessory and hypoglossal and they are designated
by Roman numerals one through 12 and most of the time depending on who's your instructor
and what they're expecting you to do they'll accept either answer they will accept either
olfactory or cranial nerve one as an answer for a question involving that nerve so as we mentioned
at the beginning the cranial nerves can either be multiple modalities or only single modalities and
so let me go through them step by step to talk about which one does what the olfactory nerve
is sensory and it is responsible for your sense of smell the optic nerve is also sensory and is
how information gets from your retina back into your brain the oculomotor nerve is motor and it
operates several of the muscles that move your eyeball around in the orbit the trochlear is
another motor nerve that innervates one specific extra ocular muscle the trigeminal nerve is
mixed it is responsible for the innervating the muscles of mastication so the ones that allow you
to chew and it is also going to provide sensory information from your face and the inside of your
oral cavity the abducens nerve is motor and it innervates one specific muscle the lateral rectus
the facial nerve innervates the muscles of facial expression and carries one's special sensory
modality it carries taste to the anterior part of your tongue the vestibulocochlear nerve is all
sensory and it's from your ear both the cochlea which is responsible for your sense of hearing and
the vestibular apparatus which is responsible for your sense of balance the glossopharyngeal nerve
is mixed it has an autonomic component it has a sensory component and it has a motor component the
vagus again is mixed it has a sensory component and a large parasympathetic component and we'll
talk about that in in a slides presentation all of its own the spinal accessory nerve is motor
and it's motor to two specific muscles the trapezius and the sternocleidomastoid muscle
and the hypoglossal nerve the last one is also only motor and it is motor to the intrinsic and
extrinsic muscles of the tongue now you'll notice that these go in you know there's O O O T T A f a
g v s h if you look up online you're gonna see a million and one different mnemonic devices for
remembering the order of the cranial nerves when I was mmm first-year graduate student I
learned on old Olympus towering top a fin and German viewed some hops you know I don't and
it worked for me it has worked for me up to this point in my life you will find your own mnemonic
for remembering the order of the cranial nerves and what each one stands for so what do I want
you to know I want you to know how many cranial nerves are I want you to know what their names
are I want you to know their numbers that go with the names and then what modality are they sensory
are they motor or do they carry both if you know those things then you're ready for the assessment