vagus and phrenic nerves Flashcards
describe the pathway of the vagus nerve in the HEAD
- originates in brainstem
- exits cranium via jugular foreamen
- auricular branch
describe the pathway of the vagus nerve in the NECK
- travels inferiorly in the carotid sheath (w/common carotid and internal jugular )
- has several branches in neck
- divides into L&R at base of neck
what are the branches of the vagus nerve that arise in the neck?
- pharyngeal branch
- superior laryngeal
- recurrent laryngeal
what does the pharyngeal branch of the vagus nerve supply?
motor to pharynx constrictor muscles
what does the superior laryngeal branch of the vagus nerve supply?
internal branch - motor to cricothyroid
external branch - viscera sensory to laryngopharynx and superior pharynx
what does the recurrent laryngeal branch of the vagus nerve supply?
only on right
- motor to intrinsic muscles of the larynx
what does the auricular branch of the vagus nerve supply?
somatic sensory for the external accoustic meatus
how does the left vagus nerve travel from the neck to the thorax?
- inferior to common carotid & subclavian
- posterior to sternoclavicular joint
- enters thorax
how does the right vagus nerve travel from the neck to the thorax?
- anterior to subclavian
- posterior to sternoclavicular joint
- enters thorax
what are the vagal branches in the thorax?
- the posterior (R) and anterior (L) vagal trunks
- the left recurrent laryngeal
- the cardiac branches
what do the thoracic vagal trunks of the vagus nerve supply?
- supply to oesophageal plexus
what does the left recurrent laryngeal branch of the vagus nerve supply?
- intrinsic muscles of the larynx
what do the cardiac branches of the vagus nerve supply?
- visceral sensation of the heart
- parasympathetic regulation of heart rate
how do the L&R vagal nerves enter the abdomen?
- go through the oesophageal hiatus in diaphragm
what doe the terminating vagus branches in the abdomen supply?
parasympathetic innervation of the GI system
- contracts smooth muscle
- glandular secretions
(oesophagus, stomach, bowels)
what is the special sensory function of the vagus?
- taste (minor role)
OVERVIEW: what are the sensory functions of the vagus?
somatic
1. external acoustic meatus
viscera
- laryngopharynx
- superior larynx
- heart
- GI tract
OVERVIEW: what are the motor functions of the vagus?
- constrictor muscles of pharynx
- intrinsic muscles of larynx
- soft palate
OVERVIEW: what are the parasympathetic functions of the vagus?
- regulates heart rate
- contractions and secretions in GI tract
where does the phrenic nerve originate for?
C3,4,5
lateral border of anterior scalene muscle (on L&R side)
at what point does the course of the L&R phrenic nerves start to differ?
at subclavian vein
describe the anatomical route of the right phrenic vein from subclavian vein to diaphragm
- passes over right subclavian artery laterally
- enters thorax via superior thoracic arpeture
- descends ant.along right lung root
- along RA pericardium
- pierces diaphragm at IVC opening
describe the anatomical route of the left phrenic vein from subclavian vein to diaphragm
- passes over right subclavian artery medially
- enters thorax via superior thoracic arpeture
- descends ant.along left lung root
- along LV pericardium
- pierces diaphragm on inferior surface
motor function of phrenic?
innervates diaphragm
sensory function of phrenic?
peritoneum and pleura of the diaphragm
pericardium and pleura of the mediastinum
