Vagus Nerve (CNX)

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Vagus Nerve (CNX)

Main Text

TERMINOLOGY

Abbreviations

• Vagus nerve (CNX)

Definitions

• CNX: Longest and one of most complex cranial nerves (CN) with diverse functions, including parasympathetic (PS) innervation of neck, thoracic and abdominal viscera
• Involved in autonomic regulation of cardiovascular, respiratory, and gastrointestinal systems
• Additional innervation

Motor to majority of soft palate, pharynx, larynx, and palatoglossus tongue muscle

Visceral sensation from larynx, esophagus, trachea, thoracic and abdominal viscera

Sensory nerve to external tympanic membrane (TM), external auditory canal (EAC), and external ear

Taste from epiglottis

IMAGING ANATOMY

Overview

• Longest of CN, extending from medulla to colon
• Segments: Intraaxial, cisternal, skull base, and extracranial

Intraaxial Segment

• Vagal nuclei are in upper and middle medulla

Motor fibers originate in nucleus ambiguus

Taste from epiglottis goes to solitary tract nucleus

Sensory fibers from viscera go to dorsal vagal nucleus (afferent component)

PS fibers project from dorsal vagal nucleus (efferent component)

Sensations from meninges and ear to spinal nucleus CNV

Cisternal Segment

• Nerve fibers exit lateral medulla in postolivary sulcus inferior to CNIX and superior to bulbar portion of CNXI

Skull Base Segment

• Enters pars vascularis portion of jugular foramen (JF)

With CNXI (shared fibrous sheath) and jugular bulb

Superior vagal (jugular) ganglion is found within JF

Extracranial Segment

• Exits JF into nasopharyngeal carotid space
• Inferior vagal (nodose) ganglion lies just below skull base
• Travels posterolateral to carotid artery into thorax

Passes anterior to aortic arch on left and subclavian artery (SCA) on right
• Forms plexus around esophagus and major blood vessels to heart and lungs
• Esophageal plexus nerves provide PS supply to stomach
• Innervation to intestines and visceral organs follows arterial blood supply

Extracranial Branches in Head and Neck

• Auricular branch (Arnold nerve)

Sensation from external surface of TM, EAC, external ear

Arises from superior vagal ganglion within JF, also has CNIX branches

Passes through mastoid canaliculus extending from posterolateral JF to mastoid segment CNVII canal

Enters EAC via tympanomastoid fissure
• Pharyngeal branches

Pharyngeal plexus exits just below skull base

Sensory to epiglottis, trachea, and esophagus

Motor to soft palate [except tensor veli palatini muscle (CNV3)] and pharyngeal constrictor muscles

Carotid sinus branch (Hering nerve)

– Formed by small CNIX branch and branch from CNX

– Supplies carotid sinus wall baroreceptors and carotid body chemoreceptors
• Superior laryngeal nerve

Motor to cricothyroid muscle (external branch)

Sensory internal branch to hypopharynx and supraglottis

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Tags: Imaging Anatomy Brain and Spine

Mar 13, 2021 | Posted by admin in NUCLEAR MEDICINE | Comments Off

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