Anatomy of vagus nerve

Question 1

Functions of vagus nerve

Answer 1

Somatic sensory
Visceral sensory
Special sensory
Somatic motor
Visceral motor

Question 2

Course of vagus nerve to abdomen

Answer 2

Vagus nerve
→ leave jugular foramen
→ penetrate carotid sheath
→ course along common carotid artery

→ esophageal hiatus….
→ supply visceral organs of abdomen

Question 3

Course of vagus nerve along the neck

Answer 3

Vagus nerve gives rises to
(1) superior laryngeal nerve - give branches to internal & external laryngeal nerves
(2) pharyngeal branches
(3) recurrent laryngeal nerve
=> Provide branchial motor innervation to muscles of 4th & 6th pharyngeal arches

Question 4

Which branches of CN X provide branchial motor in- nervation? Which structures do they innervate?

Answer 4

Superior laryngeal nerve, pharyngeal branches, recurrent laryngeal nerve
=> innervate palate, pharynx

; larynx => swallowing, phonation

Question 5

Which branches of vagus nerve gives the sensory info?

Answer 5

1) Superior laryngeal n provides sensory info - Epiglottis

• Base of tongue
• Epiglottic glands
• Mucous membrane surrounding entrance of larynx

(2) Recurrent laryngeal nerve provides sensory info - Structures below vocal folds

Question 6

Describe somatic (branchial) motor fibers pathway

Answer 6

Nucleus ambiguus

• > cell bodies of lower motor neurons
• > efferent fibers travel to muscles of 4th & 6th pharyn- geal arches

(4th) All muscles of pharynx except stylopharyngeus m
- All muscles of palate except tensor veli palitini
6th - All intrinsic muscles of larynx except cricothy- roid)

Question 7

Describe somat- ic sensory fibers pathway

Answer 7

Receive general sensory info from…

• Mucosa of larynx
• Dura matter surrounding posterior cranial fossa
• Small section of skin of external ear
• Posteroinferior aspect of external auditory canal & tympanic membrane

-> vagus nerve

• >
  (1) inferior vagal ganglion - general sensation from larynx
  (2) superior vagal ganglion - general sensation from ear & dura matter

-> spinal trigeminal nucleus

Question 8

Describe viscer- al sensory fibers pathway

Answer 8

Receive sensory info from

• Mucosa of laryngopharynx
• larynx
• aortic body chemoreceptors
• Thoracic & abdominal viscera
• *→ inferior vagal ganglion**
• *→ synapse in nucleus of solitary tract**

Question 9

Describe special sensory fibers pathway

Answer 9

Sensory info from epiglottic region & laryngopharynx

→ inferior vagal ganglion

→ gustatory part of nucleus of solitary trac

Question 10

Describe parasympathetic fibers pathway

Answer 10

!!! Visceral motor innervation - Esophagus

• *- Heart**
• *- Digestive tract**
• *(1) Preganglionic fibers from dorsal motor nucleus of vagus nerve**
• *-> synapse at various ganglion**
• *-> postganglionic fibers synapse at target organs**