Midterm III: Facial Nerve, CN VII (Ben)

Question 1

What are the 4 nuclei of the facial nerve (VII) ?

What type is each?

Where are they?

Answer 1

1. Facial Nerve Nucleus
   
   • BM + SVM … lower pons
2. Superior Salivatory Nucleus
   
   • GVM … lower pons
3. Solitary Tract Nucleus
   
   • SVS (taste) … medulla
4. Spinal Trigeminal Nucleus
   
   • GSS (protopathic) … from pons to C1-2

Question 2

What is the brain exit of the CN VII (Facial N.)?

What is the dural exit?

What is the skull exit?

Answer 2

brain - btwn pons + brachium pontis, posteriorly

dural - internal acoustic meatus (fundus)

skull - internal acoustic meatus, facial canal, stylomastoid foramen

Question 3

What is the ganglion within the facial canal?

Many fibers pass through it but only 2 types synapse here.

What type and from which nerves?

Answer 3

Geniculate Ganglion

1. SVS - from chorda tympani (ant 2/3 tongue, taste)
2. GSS - from posterior auricular branch (protopathic, external ear)

Question 4

What is the first branch of the facial nerve?

What type of nerve is it + what does it innervate?

Where does it arise from?

Answer 4

Greater Petrosal Nerve

• GVM innervating lacrimal gland
• from the geniculate ganglion

(but just from fibers passing through, no synapse there)

Question 5

Describe the course of the greater petrosal nerve from its origin to the organ it innervates.

Answer 5

1. Exits petrous part of temporal bone via hiatus for greater petrosal nerve
2. Exits middle cranial fossa via foramen lacerum
3. Joins with deep petrosal nerve (sympathetic) to form Vidian nerve
4. Travels through Pterygoid Canal (of Vidius)
5. Synapses in Pterygopalatine Ganglion (GVM)
6. Joins Zygomatic Nerve** (V/2) through **Inferior Orbital Fissure
7. Joins lacrimal nerve** to innervate the **lacrimal gland

Question 6

How does the greater petrosal nerve leave the petrous part of the temporal bone?

And then how does it exit the middle cranial fossa of the skull?

Answer 6

temporal bone - via hiatus for greater petrosal nerve

skull - via foramen lacerum

Question 7

What nerve does the greater petrosal nerve join with as it exits the skull?

What nerve does this combination create?

Answer 7

Deep Petrosal Nerve (sympathetic, from int. carotid plexus)

• creates the Vidian Nerve** or **Nerve of the Pterygoid Canal

Question 8

Where does the Vidian nerve end?

And what kind of neurons are there?

Answer 8

Pterygopalatine Ganglion

• multi-polar neurons carrying parasympathetic info

Question 9

How do parasympathetic fibers originating from the greater petrosal nerve eventually enter the orbit?

Answer 9

inferior orbital fissure

Question 10

What are the 4 intra-cranial branches of the facial nerve?

Answer 10

1. Greater Petrosal N.
2. Stapedius N.
3. Chorda Tympani N.
4. Sensory Auricular Branch

Question 11

What kind of nerve is the stapedial nerve and why?

Answer 11

Branchiomotor

• it innervates the stapedius muscle which is a muscle of the 2nd pharyngeal arch

Question 12

How does the chorda tympani exit the skull?

Answer 12

Petrotympanic Fissure

or

Glaserian Fissure

Question 13

How does the facial nerve exit the skull to give its extra-cranial branches?

Answer 13

via the stylomastoid foramen

Question 14

What are the extra-cranial branches of CN VII?

Answer 14

1. Posterior Auricular N.
2. Digastric Branch
3. Stylohyoid Branch
4. Parotid Plexus (w/in parotid gland)

Question 15

What are the nerves of the parotid plexus?

(5 nerves/branches in 2 groups)

Answer 15

Temporofacial:

• Temporal Branches
• Zygomatic Branches
• Buccal Branches

Cervicofacial:

• Marginal Mandibular Branch
• Cervical Branch

Question 16

Which branch of CN VII innervates the peri-auricular muscles + occipital belly of occipitofrontalis?

Answer 16

Posterior Auricular Nerve

Question 17

What does the digastric branch of the extra-cranial facial nerve innervate?

Answer 17

ONLY the posterior belly of the digastric

Question 18

What is the general visceromotor nucleus of CN VII?

Answer 18

Superior Salivatory Nucleus

Question 19

What is the branchiomotor nucleus of CN VII?

What branchial structures does it innervate?

Answer 19

Facial Nucleus

Muscles of the 2nd Pharyngeal Arch:

• Mimetic muscles
• Platysma
• Stapedius
• Stylohoid
• Auricular muscles
• Digastric, posterior belly

MPS SAD

Question 20

What is the general visceromotor nucleus of CN VII?

Answer 20

Superior Salivatory Nucleus

• taste innervation to ant. 2/3 tongue via chorda tympani

Question 21

What is the general somatosensory nucleus of CN VII?

Answer 21

Spinal Trigeminal Nucleus

• protopathic sensibility via sensory auricular branch

Question 22

What part of CN VII innervates the platysma?

Answer 22

Cervical Branch

• connecting with Transverse Cervical Nerve to create Superficial Cervical Ansa

Question 23

Fibers from what two types of nuclei make up the intermediate nerve which is associated with CN VII?

And what are the nuclei?

Answer 23

GVM - superior salivatory nucleus

SVS - solitary nucleus

(extra: nervus intermedius enters facial canal with facial nerve as the facial trunk)