Midterm III: Cranial Nerves III, IV, VI, IX (Ben)

Question 1

What are CN III’s two nuclei?

What type of nuclei are they?

Where are they?

Answer 1

1. Edinger-Westphal (GVM)
2. Oculomotor Nucleus (SM)

Both in the midbrain, superior collicle level.

Question 2

What is the brain exit of CN III?

Dural exit?

Skull exit?

Answer 2

brain - interpeduncular fossa

dural - cavernous sinus wall

skull - superior orbital fissure

Question 3

What are the 2 branches of the oculomotor nerve?

Answer 3

1. Superior
   
   • ​​superior rectus
   • levator palpebrae superioris
2. Inferior
   
   • ​​inferior/medial rectus
   • inf. oblique
   • pre-synaptic GVM fibers

Question 4

Where do CN III’s general visceromotor fibers end?

Answer 4

• GVM fibers end in the Ciliary Ganglion (on multi-polar neurons)

Question 5

What does the superior branch of CN III supply?

Answer 5

• levator palpebrae superioris
• superior rectus

Question 6

What does the inferior branch of CN III supply?

Answer 6

• medial rectus
• inferior rectus
• inferior oblique
• presynaptic GVM fibers to ciliary ganglion

Question 7

What are the postganglionic parasympathetic fibers originating from CN III called?

What do they innervate?

Answer 7

E-W Nucleus fibers synapse in ciliary ganglion and go on to form…

Short Ciliary Nerve

which innervates…

• Ciliaris Muscle
• Sphincter Pupillae

Question 8

What is the nucleus for CN IV?

Where is it?

Answer 8

Trochlear Nucleus

(SM, crossed)

• in the midbrain, inferior collicle level

Question 9

What is the brain exit of CN IV?

Dural exit?

Skull exit?

Answer 9

brain - below inferior colliculi

dural - lateral wall cavernous sinus

skull - superior orbital fissure

Question 10

What muscle is innervated by CN IV?

Answer 10

superior oblique

Question 11

What is the nucleus of CN VI?

Where is it?

Answer 11

Abducens Nucleus

(SM)

• in the pons

Question 12

What is the brain exit of CN VI?

Dural exit?

Skull exit?

Answer 12

brain - ponto-medullary junction, both sides foramen caecum

dural - cavernous sinus (via Dorello’s canal)

skull - Superior Orbital Fissure

Question 13

What muscle does CN VI innervate?

Answer 13

lateral rectus

Question 14

What are the 5 nuclei of the glossopharyngeal nerve (CN IX)?

What types of nuclei are they?

(Extra: where are they?)

Answer 14

1. Inferior Salivatory Nucleus - GVM
   
   • (P-M junction)
2. Nucleus of Lateral Ala Cinerea - GVS
3. Solitary Nucleus - SVS
4. Nucleus Ambiguus - BM
5. Spinal Trigeminal Tract - GSS

(2-5 in open medulla)

InS.LAC.Sol.Am.STri

Question 15

What is the brain exit of CN IX?

Dural exit?

Skull exit?

Answer 15

brain - lateral parolivary sulcus

dural - jugular foramen

skull - jugular foramen

Question 16

Which branchial arch is the glossopharyngeal nerve associated with?

Answer 16

3rd branchial (pharyngeal) arch

Question 17

What branchial arch-related muscle does CN IX innervate?

Answer 17

stylopharyngeus

Question 18

What are the 4 main branches of the glossopharyngeal nerve?

(3 branches + 1 plexus)

Answer 18

1. Tympanic Nerve (of Jacobson)
2. Communicating Branch to Auricular Branch of Vagus (Arnold’s Nerve)
3. Carotid Branch (Hering’s Nerve)
4. Pharyngeal Plexus

Tym.Comm.Car.Phar

Question 19

Where does the tympanic nerve (of Jacobson) start and end?

and how does it get there?

Answer 19

Start - Inferior Ganglion of CN IX, just outside of jugular foramen

…hooks back into skull via Tympanic Canaliculus

End - Tympanic Plexus, within tympanic cavity, giving 3 branches

Question 20

What 3 branches does the tympanic nerve give after its tympanic plexus within the tympanic cavity?

Answer 20

1. Lesser Petrosal Nerve
2. Deep Petrosal Nerve
3. Tympanic Branches (—> tymp. cavity mucosa)

Question 21

How do the inferior salivatory nucleus‘ fibers reach their target?

And what is the target?

Answer 21

GVM fibers from the inf. salivatory nucleus travel…

1. via CN IX to its inferior ganglion
2. as tympanic nerve to tympanic plexus
3. as lesser petrosal nerve to otic ganglion
4. as postsynaptic parasympathetic fibers to the parotid gland

Question 22

Where does the carotid branch of CN IX begin?

Ganglion?

End?

(in the direction of transmission)

Answer 22

Begin - baro-/chemoreceptors of carotid body

Ganglion - Inferior Ganglion of CN IX (pseudounipolar, not synapse)

End - Lateral Ala Cinerea Nucleus (GVS)

Question 23

What is the branchiomotor nucleus of CN IX and what does it innervate?

Where do its fibers synapse?

Answer 23

Nucleus Ambiguus

• innervates pharyngeal muscles via pharyngeal plexus
• directly innervates stylopharyngeus via its own branch
• its fibers pass through both sup/inf glossopharyngeal ganglia without synapsing

Question 24

What is the general somatosensory nucleus of CN IX?

Where do its fibers synapse?

Answer 24

Spinal Trigeminal Nucleus

• synapse in the superior ganglion of CN IX

(just inside the jugular foramen)

Question 25

What does the spinal trigeminal tract innervate via the glossopharyngeal nerve?

Answer 25

GSS innervation to…

• Oropharynx
• Pharyngeal Tonsil
• Tongue, Post. 1/3
• Tympanic Cavity

OPTT

Question 26

To where does CN IX give taste sensation?

Via what ganglion?

And to what nucleus?

Answer 26

• Posterior 1/3 Tongue

- Inferior Ganglion of CN IX

- Solitary Nucleus