cranial nerves (theory) Flashcards
how many cranial nerves are there?
there are 12 cranial nerve pairs
- olfactory
- optic
- oculomotor
- trochlear
- trigeminal
- abducens
- facial
- vestibulocochlear
- glossopharyngeal
- vagus
- accessory
- hypoglossal
CN I
the olfactory nerve
- helps with smell
- ends at the olfactory bulbs
olfactory nerve pathway
the olfactory nerve fibers (hair cells) of the nerve receive stimuli, this stimulates the olfactory nerve which runs down the olfactory tract
this eventually ends in the insula (olfactory cortex)
CN II
the optic nerve
- senses visual stimuli (purely sensory)
- first goes to the diencephalon
- then goes to the occipital lobe
recall that pretty much all sensory input goes through the thalamus
what is the relay of the optic nerve in the thalamus (LGN)
lateral geniculate nucleus
why are the eyes cup shaped?
they are cup shaped bc they contain nasal and temporal fibers
these fibers are named by their spatial position
the nasal fibers see lateral vision
the temporal fibers see medial vision
what fibers of the retina cross?
the nasal fibers cross at the optic chiasm
CN III
the oculomotor nerve
- this controls the extra and intra-ocular eye muscles EXCEPT the lateral rectus and the superior oblique
- ends at the extra-ocular eye muscles
CN IV
trochlear nerve
- supplies the superior oblique
- ends at the superior oblique
CN V
trigeminal nerve
- supplies muscles of mastication
- provides facial sensation along its 3 branches
- the ophthalamic and maxillary branches end at the pons
- mandibular branch ends at the mandibular muscles
what are the 3 branches of the trigeminal nerve?
- ophthalamic branch
- maxillary branch
- mandibular branch
CN VI
abducens nerve
- supplies the lateral rectus
- ends at the lateral rectus
CN VII
facial nerve
- supplies the facial muscles
- provides sensation for the face and taste
where does the sensory part of the facial nerve end?
the pons
where does the motor part of the facial nerve end? (think literally)
the face muscles
CN VIII
vestibulocochlear nerve
- purely sensory, it provides balance and hearing
- ends at the pons
CN IX
glossopharyngeal nerve
- it provides sensation and motor control BUT it does NOT move the tongue
- senses tongue pain
- controls pharyngeal muscles for swallowing
- also supplies the posterior 1/3 of the tongue
where does the glossopharyngeal nerve (CN IX) end?
- sensory info = medulla
- visceral motor = parotid salivary gland
- somatic motor = pharyngeal muscles
carotid body, sinus and artery (prof’s notes)
the baroreceptors monitor the blood pressure and link with the glossopharyngeal and vagus nerve
CN X
the vagus nerve
*the only cranial nerve to leave the head and neck
*also produces ACh
*the parasympathetic nerve
- sensory info from the organs
- sensory info to the organs
where do the parts of the vagus nerve end?
- sensory = autonomic centers of the medulla
- somatic = muscles of the palate and pharynx
- visceral motor = respiratory, cardio, digestive organs
CN XI
accessory nerve
- controls the sternocleidomastoid and trapezius
- the external branch ends at the sternocleidomastoid and trapezius
CN XII
hypoglossal nerve
- controls tongue movement
- ends at the tongue muscles
mnemonic aid for the cranial nerves
oh –> olfactory
once –> optic
one –> oculomotor
takes –> trochlear
the –> trigeminal
anatomy –> abducens
final –> facial
very –> vestibulocochlear
good –> glossopharyngeal
vacations –> vagus
are –> accessory
heavenly –> hypoglossal
what is the positioning of the accessory and hypoglossal nerves?
since the accessory nerve supplies muscles below the tongue, the accessory nerve sits below the hypoglossal nerve even though it is CN XI
