Flashcards in Facial Nerve Deck (34):
Which branchial arch does the facial nerve supply?
2nd branchial arch
What are the 2 parts of the facial nerve?
Facial nerve proper (pure motor nerve)
What are the 4 muscles that the facial nerve supplies motor output to?
1. Muscles of facial expression
4. Posterior belly of the digastric muscle
Between what 2 structures is the nervous intermedius between?
Between the facial nerve proper and the vestibulocochlear nerve
What 3 fiber types are contained in the nervus intermedius?
Preganglionic parasympathetic fibers
Some general sensory fibers
What region does the facial nerve first enter, and with what other cranial nerve does it enter this area with?
First enters the internal acoustic meatus, along with the vestibulocochlear nerve
Where does the facial nerve enter as it courses through the petrous portion of the temporal bone?
What does it eventually enter after that?
What happens when it reaches this point, and what is this part called?
Enters through the facial canal in the petrous portion of temporal bone
Travels through this until reaching the cavity of the middle ear (tympanic cavity)
When it reaches this part, it turns back sharply forming knee shaped bend (genu) which is enlarged and contains all sensory ganglion of facial nerve
What is the name of the knee shaped bend that contains all the sensory ganglion of the facial nerve? Where is it?
It is at the tympanic cavity where the genu is formed
Enlarged and is called the geniculate ganglion
Through which foramen does the facial nerve leave the skull?
Through the stylomastoid foramen
What type of nerve is the facial nerve proper?**
It is a pure motor nerve
After the geniculate ganglion, what is the first muscle that gets a branch from the facial nerve proper?
The stapedius muscle
What are the 2 branches that the facial nerve sends off after emerging from the stylomastoid foramen?
Posterior auricular branch (to facial muscles behind the ear)
Branch to the stylohyoid and posterior belly of digastric
Once the facial nerve proper enters the parotid gland, what are the 5 terminal branches that it gives rise to?
What types of fibers are contained in the nervus intermedius?
Preganglionic parasympathetic fibers
Some general sensory fibers
What are the contributions of the sensory fibers of the nervus intermedius portion of the facial nerve?
The contributions are minimal because there is a lot of overlap
Where are all the cell bodies of the sensory fibers (taste and general sensory) of the nervus intermedius portion of the facial nerve? What type of cells are these?
Contained in the geniculate ganglion, and are pseudounipolar neurons
What are the 2 principal branches of the nervus intermedius?
-Greater petrosal nerve
At what level is the greater petrosal nerve given off of the nervus intermedius portion of the facial nerve?
The greater petrosal nerve is given off at the level of the geniculate ganglion
Through which hole in the skull does the greater petrosal nerve enter the middle cranial fossa?
Through the hiatus of the greater petrosal nerve
Which canal does the greater petrosal nerve enter after crossing the foramen lacerum in the middle cranial fossa? What nerve joins it there, and what fibers does it contain (and where did those fibers originate)?
Enters the pterygoid canal
Joined by the deep petrosal nerve
Deep petrosal nerve has postganglionic sympathetic fibers
Has those fibers from the internal carotid plexus
What is the name of the nerve that is the joining together of the greater petrosal nerve and the deep petrosal nerver? Where is this nerve?
It is the nerve of the pterygoid canal (and is located in the pterygoid canal)
Describe the path of the deep petrosal nerve once it enters the pterygopalatine fossa.
It enters the pterygopalatine fossa and passes through the pterygopalatine ganglion without synapsing.
Provides all branches of the maxillary division of the trigeminal (V2) with postganglionic sympathetic fibers
Which fibers synapse in the pterygopalatine ganglion?
The preganglionic parasympathetic fibers of the greater petrosal nerve synapse there
Which 7 groups of nerves do the postganglionic parasympathetic fibers originating in the pterygopalatine ganglion join up with?***
Greater and lesser palatine nerves
Posterior nasal branches
Zygomatic nerve (which ultimately passes them off to the lacrimal nerve V1)
Superior alveolar nerves
Where do the taste fibers of the greater petrosal nerve go?
They pass through the ganglion without synapsing and join the greater and lesser palatine nerves to supply taste buds of the palate
When does the chorda tympani leave the facial nerve? Where does it enter from there?
It branches off of the facial nerve just before the facial nerve enters the stylomastoid foramen.
After that, it enters the tympanic cavity
What nerve will be disturbed with any issues of the middle ear**?
The chorda tympani because it enters the tympanic cavity (the middle ear)
Describe the course of the chorda tympani in the tympanic cavity and afterwards. Through what does the chorda tympani leave the tympanic cavity, where does it enter afterwards, and what nerve does it join with? What is this nerve a branch of?
The chorda tympani passes the handle of the malleus (Shadow of the nerve can be seen through tympanic membrane)
Enters the tympanic cavity through the petrotympanic fissure
Enters the infratemporal fossa where it joins the lingual nerve
The lingual nerve is a branch of the posterior division of the mandibular branch (V3) of trigeminal
Where are the taste fibers of the chorda tympani go, and via what?***
The taste fibers travel via the lingual nerve to supply the anterior 2/3 of the tongue
!!Because the anterior 2/3 of the tongue is supplied by the facial nerve
Where do the preganglionic parasympathetic fibers of the chorda tympani synapse at, and where do the postganglionic fibers proceed afterwards?
The preganglionic parasympathetic fibers of the chorda tympani synapse in the submandibular ganglion.
Postganglionic fibers go to the submandibular gland or are distributed via the lingual nerve to the sublingual and lingual salivary glands (for salivation during eating)
What are the symptoms if there is a lesion at the level of the stylomastoid foramen, and which branches are compromised?
If the lesion occurs at the stylomastoid foramen, it is known as Bell's Palsy
The 2 immediate branches given off by the facial (posterior auricular nerve and the nerve to the stylohyoid and posterior belly of the digastric) are compromised, as well as the 5 terminal branches in the parotid gland (temporal, zygomatic, buccal, mandibular, cervical)
Symptoms: muscles of facial expression and paralyzed (glandular and taste intact)
Cannot close eyelid on ipsilateral side
Corner of mouth and lip droop on the affected side (drooling)
Food accumulates in the gums and cheek in mouth (Buccinator muscle paralyzed)
What are symptoms if there is a lesion in the facial canal between the departure of the chorda tympani and the nerve to stapedius? Which branches are affected?
All symptoms of Bell's Palsy (loss of terminal branches after stylomastoid foramen)
Also, loss of taste on anterior 2/3 of tongue
Reduced salivation (dry mouth of xerostomia)
(due to the loss of parasympathetic innervation of these areas and the loss of taste fibers carried by the chorda tympani)
What are the symptoms if there is a lesion to the facial nerve proximal to the departure of the stapedius?
All effects of Bell's Palsy
Plus loss of taste on anterior 2/3 of tongue/reduced salivation
Plus hyperacusis (Increased sensitivity to sound)