13. CN - IX/X

Question 1

CN IX

Name, where it exits brain, features, components/branches, primordium

Answer 1

Glossopharyngeal N. - sensory to pharynx
Exits: Jugular Canal (w/ CN X, XI, Int Jugular Vein)

Superior Ganglia: for general sensation
Inferior Ganglia: for special and visceral sensation

Visceral sensory: to naso- and oropharynx (GAG REFLEX) and to middle ear
Taste: to back of tongue
Branchiomotor: to stylopharyngeus m. (tiny, no fx)
Parasymp: to otic ganglion (to V3 to parotid gland)
Route of Parasymp: Tympanic nerve = [otic ganglion] lesser petrosal nerve = auriculotemporal nerve (V3)

Primordium: Branchial Arch 3
Pretrematic: Tympanic Nerve

Question 2

CN X

Name, where it exits brain, features, components/branches, primordium

Answer 2

Vagus N. - motor to pharynx
Exits: Jugular canal (w/ CN IX, XI, int jugular vein)

Superior ganglion: General sensation
Inferior Ganglion: special and visceral sensation

Branchiomotor: to pharynx/larynx (test by saying “aah” to move soft palate)
Visceral Sensory: to most of foregut/midgut
General Sensory: to ext ear and posterior fossa dura
Taste: tiny bit to laryngopharynx
Special Sensory: to aortic sinus/body (monitor BP/blood gas)
Presynaptic Parasymps: craniosacral outflow, helps GI peristalsis

Primordium: Branchial Arch 4/6 (cranial root of CN XI is now part of CN X - accessory to vagus)

Question 3

What are the branches of CN X within the neck?

Answer 3

1. Pharyngeal N. = motor to constrictor/palate muscles (not tensor palati)
2. Superior Laryngeal N. = splits (carries parasymps)
   2a. Internal Laryngeal N. = visceral sensory to larynx above vocal cords (COUGH REFLEX)
   2b. External Laryngeal N. = motor to cricothyroid m.
3. Inferior (recurrent) Laryngeal N. = motor to all other laryngeal muscles; visceral sensory below vocal cords (carries parasymps)