Facial Nerve

Question 1

Which branchial arch does the facial nerve supply?

Answer 1

2nd branchial arch

Question 2

What are the 2 parts of the facial nerve?

Answer 2

Facial nerve proper (pure motor nerve)

Nervus intermedius

Question 3

What are the 4 muscles that the facial nerve supplies motor output to?

Answer 3

1. Muscles of facial expression
2. Stapedius
3. Stylohyoid
4. Posterior belly of the digastric muscle

Question 4

Between what 2 structures is the nervous intermedius between?

Answer 4

Between the facial nerve proper and the vestibulocochlear nerve

Question 5

What 3 fiber types are contained in the nervus intermedius?

Answer 5

Taste fibers
Preganglionic parasympathetic fibers
Some general sensory fibers

Question 6

What region does the facial nerve first enter, and with what other cranial nerve does it enter this area with?

Answer 6

First enters the internal acoustic meatus, along with the vestibulocochlear nerve

Question 7

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?

Answer 7

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

Question 8

What is the name of the knee shaped bend that contains all the sensory ganglion of the facial nerve? Where is it?

Answer 8

It is at the tympanic cavity where the genu is formed

Enlarged and is called the geniculate ganglion

Question 9

Through which foramen does the facial nerve leave the skull?

Answer 9

Through the stylomastoid foramen

Question 10

What type of nerve is the facial nerve proper?**

Answer 10

It is a pure motor nerve

Question 11

After the geniculate ganglion, what is the first muscle that gets a branch from the facial nerve proper?

Answer 11

The stapedius muscle

Question 12

What are the 2 branches that the facial nerve sends off after emerging from the stylomastoid foramen?

Answer 12

Posterior auricular branch (to facial muscles behind the ear)
Branch to the stylohyoid and posterior belly of digastric

Question 13

Once the facial nerve proper enters the parotid gland, what are the 5 terminal branches that it gives rise to?

Answer 13

1. Temporal
2. Zygomatic
3. Buccal
4. Mandibular
5. Cervical

Question 14

What types of fibers are contained in the nervus intermedius?

Answer 14

Taste fibers
Preganglionic parasympathetic fibers
Some general sensory fibers

Question 15

What are the contributions of the sensory fibers of the nervus intermedius portion of the facial nerve?

Answer 15

The contributions are minimal because there is a lot of overlap

Question 16

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?

Answer 16

Contained in the geniculate ganglion, and are pseudounipolar neurons

Question 17

What are the 2 principal branches of the nervus intermedius?

Answer 17

• Greater petrosal nerve

- Chorda tympani

Question 18

At what level is the greater petrosal nerve given off of the nervus intermedius portion of the facial nerve?

Answer 18

The greater petrosal nerve is given off at the level of the geniculate ganglion

Question 19

Through which hole in the skull does the greater petrosal nerve enter the middle cranial fossa?

Answer 19

Through the hiatus of the greater petrosal nerve

Question 20

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)?

Answer 20

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

Question 21

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?

Answer 21

It is the nerve of the pterygoid canal (and is located in the pterygoid canal)

Question 22

Describe the path of the deep petrosal nerve once it enters the pterygopalatine fossa.

Answer 22

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

Question 23

Which fibers synapse in the pterygopalatine ganglion?

Answer 23

The preganglionic parasympathetic fibers of the greater petrosal nerve synapse there

Question 24

Which 7 groups of nerves do the postganglionic parasympathetic fibers originating in the pterygopalatine ganglion join up with?***

Answer 24

Greater and lesser palatine nerves
Posterior nasal branches
Nasopalatine nerve
Pharyngeal nerve
Orbital branches
Zygomatic nerve (which ultimately passes them off to the lacrimal nerve V1)
Superior alveolar nerves

Question 25

Where do the taste fibers of the greater petrosal nerve go?

Answer 25

They pass through the ganglion without synapsing and join the greater and lesser palatine nerves to supply taste buds of the palate

Question 26

When does the chorda tympani leave the facial nerve? Where does it enter from there?

Answer 26

It branches off of the facial nerve just before the facial nerve enters the stylomastoid foramen.
After that, it enters the tympanic cavity

Question 27

What nerve will be disturbed with any issues of the middle ear**?

Answer 27

The chorda tympani because it enters the tympanic cavity (the middle ear)

Question 28

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?

Answer 28

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

Question 29

Where are the taste fibers of the chorda tympani go, and via what?***

Answer 29

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

Question 30

Where do the preganglionic parasympathetic fibers of the chorda tympani synapse at, and where do the postganglionic fibers proceed afterwards?

Answer 30

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)

Question 31

What are the symptoms if there is a lesion at the level of the stylomastoid foramen, and which branches are compromised?

Answer 31

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)

Question 32

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?

Answer 32

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)

Question 33

What are the symptoms if there is a lesion to the facial nerve proximal to the departure of the stapedius?

Answer 33

All effects of Bell’s Palsy
Plus loss of taste on anterior 2/3 of tongue/reduced salivation
Plus hyperacusis (Increased sensitivity to sound)

Question 34

What are the symptoms if the entire facial nerve is lesioned at the level of the internal acoustic meatus?

Answer 34

All effects of Bell’s Palsy
Plus loss of taste on anterior 2/3 of tongue/reduced salivation
Plus hyperacusis
Plus loss of lacrimal secretion and loss of taste on palate (because of the loss of the greater petrosal nerve)