Exam 1: Unit III: CN VII; Facial Nerve Flashcards
What type of fibers does the Facial nerve carry?
(mixed CN)
- motor and sensory (special sensory for taste)
- parasympathetic fibers
What is know as the “Nerve of Facial Expression”?
Facial Nerve; CN VII
-b/c innervates many facial muscles
What is the nucleus that many preganglionic parasympathetic fibers come from that contribute to the Facial nerve?
superior salivary nucleus
Where do sensory fibers that are carried in CN VII terminate (nucleus of termination)?
upper part of the solitary nucleus
some call it solitary tract b/c the nucleus is so long
Where are the cell bodies of first order sensory neurons for the facial nerve located?
geniculate ganglion
analogous to trigeminal ganglion
What peripheral ganglion are associated with the facial nerve?
- geniculate ganglion
- pterygopalatine ganglion
- submandibular ganglion
What type of sensory information does the Facial nerve carry?
- general sensation from external ear and lateral tympanic membrane
- taste (ant. 2/3)
Where are the cell bodies for the sensory information carried in the facial nerve located? Where do they go synapse in?
geniculate ganglion (cell bodies of 1st order sensory neurons) axons will then carry info to solitary nucleus
What are the specific fibers that convey taste from the anterior part of the tongue carried in?
chorda tympani (of CN VII)
Describe the sensory pathway of the facial nerve.
- What does it supply, where does it go, and where does it synapse
Carries:
- general sensation from external ear and lateral tympanic membrane
- Taste info from ant. 2/3 tongue (via chorda tympani)
Carried to: geniculate ganglion
Synapses: solitary nucleus
What is the division line for the anterior 2/3 and the posterior 1/3 of the tongue?
sulcus terminalis
What is the primary nucleus of origin called for the facial nerve?
motor nucleus of the facial nerve
What are the axons in the motor pathway for the facial nerve from?
LMNs from motor nucleus of facial nerve
In general, what is the pathway for the LMN axons coming from the motor nucleus of the facial nerve?
exit the CNS, travel THROUGH geniculate ganglion and innervate muscles of facial expression
Where does the motor nucleus of the facial nerve receive information from?
- both cerebral hemispheres (note on muscles of inf. face)
- reticular formation
What is so interesting about the muscles in the inferior part of the face that the facial nerve supplies and where they receive information from?
the part of the motor nucleus of the facial nerve supplying muscles in inferior part of face receives info from ONLY the contralateral cortex
Where do the preganglionic parasympathetic fibers in the facial nerve come from? Where do they synapse?
Come from: superior salivary nucleus
Synapse in: pterygopalatine ganglion or submandibular ganglion
Where do the postganglionic fibers in the parasympathetic pathway of the facial nerve supply?
- lacrimal gland
- submandibular gland
- small glands in oral and nasal cavities
What is the apparent origin of the facial nerve?
laterally in the medullopontine sulcus (or cerebellopontine recess)
What is the path of fibers from the motor nucleus of the facial nerve before it exits the CNS?
first travel posteriorly and arch around the abducens nucleus
How many roots are present at the apparent origin of the facial nerve?
two
- Motor Root (facial nerve proper)
- Intermediate nerve–> carries sensory and parasympathetic fibers
What do both roots of the facial nerve enter into upon exiting the CNS?
enter the internal acoustic meatus, located in petrous part of the temporal bone
Where is the geniculate ganglion located?
the external genu of the facial nerve within facial canal
After entering the internal acoustic meatus, what do the facial nerve roots do? What is formed?
combine and form a single trunk and enter the facial canal —> then bends posteriorly, forming the external genu of the facial nerve (where the geniculate ganglion is located)
How many branches of the facial nerve are given off in the facial canal? What are they, in order?
- Greater petrosal nerve
- Nerve to the stapedius
- Chorda tympani
As the greater petrosal nerve comes off the facial nerve, how does it travel? (lengthy description)
travels anteriorward through the hiatus for the greater petrosal nerve —> re-enters petrous part of temporal bone through foramen lacerum —-> travels through pterygoid canal—> joints pterygopalatine ganglion
What type of fibers does the greater petrosal nerve carry? What do they stimulate secretion of?
(branch of CN VII) preganglionic parasympathetic fibers; stimulate secretion of: - lacrimal gland - nasal gland - palatal gland
What is another name the greater petrosal nerve can be called? (Due to what reason?)
superficial petrosal nerve
stimulate secretion of lacrimal, nasal, and palatal glands
What is the second nerve given off of the facial nerve in the facial canal? What type of fibers does it carry?
Nerve to the stapedius; contain ONLY motor fibers
What does the nerve to the stapedius supply (branch of VII)?
stapedius muscle
What is the only nerve given off of the facial nerve in the facial canal that only contains motor fibers?
nerve to the stapedius
What is the third branch coming off of the facial nerve in the facial canal? What type of fibers does it carry?
chorda tympani; carries preganglionic parasympathetic fibers and taste fibers
Describe the path of the chorda tympani once it branches of the facial nerve.
it travels THROUGH the tympanic cavity and leaves temporal bone through the pterygotympanic fissure; then combines with lingual nerve (branch of V3)
What nerve does the chorda tympani combined with after it leaves the temporal bone?
lingual nerve, a branch of mandibular division of the trigeminal nerve
Where do the fibers carried in chorda tympani go?
preganglionic parasympathetic fibers –> go to submandibular ganglion
taste fibers—-> go to tongue (with lingual nerve, branch of V3)
How do the remaining fibers of the facial nerve (after the three branches given off in the facial canal) exit the temporal bone?
through the stylomastoid foramen
All the fibers remaining of the facial nerve that are exiting the stylomastoid foramen are what type of fibers?
motor or somatosensory
How many branches are given off of the facial nerve between it exiting the stylomastoid foramen and before entering the parotid gland?
three
- the digastric branch (M)
- the stylohyoid branch (M)
- the posterior auricular branch (M and S)
What does the digastric branch of the facial nerve supply?
posterior belly of digastric muscle
What does the stylohyoid branch of the facial nerve supply?
the stylohoid muscle
Describe the path of the posterior auricular nerve, (branch of the facial nerve).
travels posterior to the ear and divides into an occipital branch and an auricular branch
What do the branches of the posterior auricular nerve supply?
- occipital branch
- auricular branch
- occipitalis
2. posterior auricular muscle, intrinsic muscles of anterior part of ear, and carriers SENSORY info
What gland does the facial nerve enter? What does it form?
parotid gland, forms parotid plexus
What does the facial nerve entering the parotid gland give rise to? Do those give rise to anything?
two trunks:
- temporofacial trunk
- cervicofacial trunk
Give rise to 5 major branches that supply muscles of facial expression
How many branches do the temporofacial and cervicofacial trunks give rise to? What are they?
Five: (supply muscles of facial expression) 1. Temporal branches 2. Zygomatic branch 3. Buccal branches 4. Marginal mandibular branch 5. Cervical branch "ten zebras bit my (massive) cat"
What do the temporal branches (branch of facial nerve) supply?
- intrinsic auricular muscles
- superior auricular muscle
- anterior auricular muscle
- orbicularis oculi
- corrugator supercilii
- frontal belly of occipitofrontalis
What muscles does the temporal branches of the facial nerve supply that is in combination with what other nerves?
Combination with zygomaticotemporal nerve (V2) and auriculotemporal branch (V3) supply:
- orbicularis oculi
- corrugator supercilii
- frontal belly of the occipitofrontalis
What combination of nerves supplies the orbicularis oculi, corrugator supercilii, and the frontal belly of the occipitofrontalis?
- Temporal branches of CN VII
- zygomaticotemporal nerve (V2)
- auriculotemporal branch (V3)
What does the zygomatic branch of the facial nerve help supply?
orbicularis oculi
What do the buccal branches of the facial nerve supply?
- buccinator
- orbicularis oris
- levator anguli oris
What does the marginal mandibular branch of the facial nerve supply?
- risorius
- muscles of chin and lower lip
What does the cervical branch of the facial nerve supply?
travels inferiority to supply the platysma
What nerve MAY the marginal mandibular branch (branch of facial nerve) joint with?
mental nerve (branch of V3, posterior divison, inferior alveolar nerve)
What nerves all help supply the orbicularis oculi muscle?
- temporal branches and zygomatic branches of facial nerve
and - zygomaticotemporal nerve (V2)
- auriculotemporal branch (V3)
What nerve does Bell’s Palsy affect? How does it manifest?
Facial nerve (CN VII); paralysis of one of the facial nerves, unilaterally
What procedure may injury the facial nerve?
Superficial parotidectomy (removal of the parotid gland)