Vagus Nerve Flashcards
How much of the vagus nerve fibres communicate from the body to the brain
80%
How much of the vagus nerve fibres communicate from the brain to the body
20%
What does the vagus nerve control
Muscles that you use to swallow and speak And body’s response to rest/relaxation
What is the vagus nerves sensory function
Innervates the skin of the external acoustic meatus and internal surfaces of the laryngopharynx and larynx
Provides visceral sensation to the heart and abdominal viscera
What is the vagus nerves special sensory function
Provides taste sensation to the epiglottis and root of the tongue
What is the vagus nerves motor function
Provides innervation to the majority of the muscles of the pharynx, soft palate and larynx
What is the vagus nerves parasympathetic function
Innervates the smooth muscle of the trachea, bronchi and gastrointestinal tract and regulates heart rhythm
What are the 4 vagal nuclei
Dorsal motor nucleus
Nucleus ambiguus
Solitary nucleus
Spinal trigeminal nucleus
What does the dorsal motor nucleus do
Supply parasympathetic efferent primarily to the gastrointestinal tract and lungs
What does the nucleus ambiguus do
Efferent fibres supply muscles of the soft palate, pharynx and larynx
Also gives rise to branchial efferent fibres and preganglionic parasympathetic neurons for the heart
What does the solitary nucleus do
Receives primary afferents from visceral organs as well as taste information
What does the spinal trigeminal nucleus do
Relay sensory information regarding pain, temperature and deep touch of the outer ear, the dura of the posterior cranial fossa and the mucosa of the larynx
What does the Auricular branch of the vagus nerve supply
Sensation to the posterior part of the external auditory canal and external ear
What does the vagus nerve pass through in the neck
The carotid sheath
How does the vagus nerve travel within the neck
Inferiorly with the internal jugular vein and common carotid artery
Where does the right vagus nerve pass
Anterior to the subclavian artery and posterior to the sternoclavicular joint entering the thorax
Where does the left vagus nerve pass
Inferiorly between the left common carotid and left subclavian arteries, posterior to the sternoclavicular joint entering the thorax
What are the 4 branches which the vagus nerve breaks into in the neck
Pharyngeal branch
Superior laryngeal nerve
Right recurrent laryngeal nerve
Left recurrent laryngeal nerve
What does the pharyngeal branch of the vagus nerve do
Provide motor innervation to the majority of the muscles of the pharynx and soft palate
What does the external laryngeal nerve of the vagus nerve do
Innervate the cricothyroid muscle of the larynx
What does the internal laryngeal nerve of the vagus nerve do
Provide sensory innervation to the laryngopharynx and superior part of the larynx
What does the right recurrent laryngeal nerve of the vagus nerve do
Innervates the majority of the intrinsic muscles of the larynx
What is the pathway of the left recurrent laryngeal nerve of the vagus nerve
Hooks underneath the aortic arch before transcending towards the larynx
In the thorax what does the right vagus nerve form
The posterior vagal trunk
In the thorax what does the left vagus nerve form
The anterior vagal trunk
What do the vagal trunks of the vagus nerve contribute to
The formation of the oesophageal plexus which innervates the smooth muscle of the oesophagus
In the thorax what are the 2 other branches of the vagus nerve
Left recurrent laryngeal nerve
Cardiac branches
What do the cardiac branches of the vagus nerve do
Innervate/regulate heart rate and provide visceral sensation to the organ
How does the vagus nerve enter the abdomen
The vagal trunks enter the abdomen via the oesophageal hiatus - an opening in the diaphragm
How does the vagus nerve terminate in the abdomen
By dividing into branches that supply the oesophagus, stomach and the small and large bowel - up to the splenic flexure
What are the muscles of the pharynx innervated by
The pharyngeal branches of the vagus nerve
What 5 pharynx muscles are innervated by the vagus nerve
Superior, middle and inferior pharyngeal constrictor muscles
Palatopharyngeus
Salpingopharyngeus
What is the stylopharyngeus innervated by
The glossopharyngeal nerve
What is the 6th pharynx muscle that is not innervated by the vagus nerve
The Stylopharyngeus muscle
What are the 5 recurrent laryngeal muscles
Thyro arytenoid
Posterior crico arytenoid
Lateral crico arytenoid
Transverse and oblique arytenoids
Vocalis
What is the external laryngeal muscle
Cricothyroid
How does the vagus nerve help cardiac function
Cardiac branches arise in the thorax conveying parasympathetic innervation to the sino atrial and atrio ventricular nodes of the heart
Stimulates reduction in the resting heart rate
What would happen to the heart rate if the vagus nerve was damaged
The resting heart rate would increase
How does the vagus nerve help with the gastrointestinal system
Provides parasympathetic innervation to the majority of abdominal organs
Sends branches to the oesophagus, stomach and intestinal tract - up to the splenic flexure of the large colon
Stimulate muscle contraction and glandular secretions in these organs
How does the vagus nerve stimulate muscle contractions in the parasympathetic nervous system
Releases acetylcholine at the synaptic junction with secreting cells, intrinsic nervous fibres and smooth muscles
Acetylcholine binds to nicotinic and muscarinic receptors to stimulate muscle contraction
How is the vagus nerve related to swallowing
It’s motor fibres innervate all striated muscles of the larynx and pharynx expect the stylopharyngeus and the tensor veli palatini muscles
Which cranial nerves does vomiting (emetic) center coordinate reflex through
Trigeminal
Facial
Glossopharyngeal
Vagus
Hypoglossal
What are the stages of vomiting occurring
Stimulus in medulla oblongata
Cranial nerve respond
Hypersalivation, pallor, sweat, tachycardia
Glottis closes - soft palate rises to close off airway
Deep inspiration diaphragm contracts
Gastroesophageal sphincter and fundus of stomach relax
Abdominal muscles contract forcefully
Antiperistaltic waves
Increased pressure forces chyme upward from stomach out of mouth
What are the 4 stages of coughing
Receptorial phase
Inspiratory phase
Compressive phase
Expiratory phase
What is the receptorial phase of coughing
Stimulation to cough receptors send an impulse via the vagus nerve
What is the Inspiratory phase of coughing
Wide opening of the glottis by contraction of the arytenoid cartilage with rapid inhalation
What is the compressive phase of coughing
Closure of the glottis following contraction of the adductor muscles of the arytenoid cartilages with consequent adduction of the vocal cords
Contraction of the abdominal muscles and other expiratory muscles resulting in an increased intrapulmonary pressure and compression of the alveoli and bronchioles
What is the expiratory phase of coughing
Vocal cords and epiglottis open causing air from lungs out
Exhalation continues until complete relaxation of the diaphragm
Which nerve is related to the afferent limb of a gag reflex
Glossopharnygeal nerve
What does the afferent limb of the glossopharyngeal nerve do during a gag reflex
Inputs to the nucleus solitarius and the spinal trigeminal nucleus
Which nerve is related to the efferent limb of a gag reflex
Vagus nerve from the nucleus ambiguus
