1. TheThe vagus nervevagus nerve is the tenth of twelve pairedis the tenth of twelve paired
cranial nervescranial nerves, and is the only nerve that, and is the only nerve that
starts in thestarts in the brainstembrainstem (within the(within the
medulla oblongatamedulla oblongata) and extends, through the) and extends, through the
jugular foramenjugular foramen, down below the, down below the headhead, to the, to the
neck, chest andneck, chest and abdomenabdomen..
2. BranchesBranches
AuricularAuricular
PharyngealPharyngeal
Superior laryngealSuperior laryngeal
Superior cervical cardiac branches of vagus nerveSuperior cervical cardiac branches of vagus nerve
Inferior cervical cardiac branchInferior cervical cardiac branch
Recurrent laryngealRecurrent laryngeal
Thoracic cardiac branchesThoracic cardiac branches
Branches to the pulmonary plexusBranches to the pulmonary plexus
Branches to the esophageal plexusBranches to the esophageal plexus
Anterior vagal trunkAnterior vagal trunk
Posterior vagal trunkPosterior vagal trunk
3. InnervationInnervation
The vagus descends from the spinal cord in theThe vagus descends from the spinal cord in the carotid sheathcarotid sheath, lateral to the carotid artery. It carries, lateral to the carotid artery. It carries
on past theon past the aortic archaortic arch to dip inferiorly behind theto dip inferiorly behind the left bronchusleft bronchus. Here it forms the. Here it forms the
pulmonary plexuspulmonary plexus, after giving rise to the recurrent laryngeal nerve., after giving rise to the recurrent laryngeal nerve.
The vagus nerve supplies motorThe vagus nerve supplies motor parasympatheticparasympathetic fibers to all the organs except the suprarenal (fibers to all the organs except the suprarenal (
adrenaladrenal) glands, from the) glands, from the neckneck down to the second segment of thedown to the second segment of the transverse colontransverse colon. The vagus. The vagus
also controls a fewalso controls a few skeletal musclesskeletal muscles, namely:, namely:
Cricothyroid muscleCricothyroid muscle
Levator veli palatini muscleLevator veli palatini muscle
Salpingopharyngeus muscleSalpingopharyngeus muscle
Palatoglossus musclePalatoglossus muscle
Palatopharyngeus musclePalatopharyngeus muscle
Superior, middle and inferiorSuperior, middle and inferior pharyngeal constrictorspharyngeal constrictors
Muscles of theMuscles of the larynxlarynx ((speechspeech).).
This means that the vagus nerve is responsible for such varied tasks asThis means that the vagus nerve is responsible for such varied tasks as heart rateheart rate, gastrointestinal, gastrointestinal
peristalsisperistalsis,, sweatingsweating, and quite a few muscle movements in the mouth, including, and quite a few muscle movements in the mouth, including speechspeech (via the(via the
recurrent laryngeal nerverecurrent laryngeal nerve) and keeping the larynx open for breathing. It also receives some) and keeping the larynx open for breathing. It also receives some
sensation from thesensation from the outer earouter ear, via the Auricular branch and part of the, via the Auricular branch and part of the meningesmeninges..
4. nuclei :nuclei :
thethe dorsal motor nucleusdorsal motor nucleus,,
thethe nucleusnucleus ambiguusambiguus
the nucleusthe nucleus solitary nucleussolitary nucleus..
5. Physical and emotionalPhysical and emotional
effectseffects
Activation of the vagus nerve typically leads to a reduction in heart rate, blood pressure,Activation of the vagus nerve typically leads to a reduction in heart rate, blood pressure,
or both. This occurs commonly in the setting of gastrointestinal illness such as viralor both. This occurs commonly in the setting of gastrointestinal illness such as viral
gastroenteritis or acute cholecystitis, or in response to other stimuli, including carotidgastroenteritis or acute cholecystitis, or in response to other stimuli, including carotid
sinus massage, Valsalva maneuver, or pain from any cause, particularly having bloodsinus massage, Valsalva maneuver, or pain from any cause, particularly having blood
drawn. When the circulatory changes are great enough, vasovagal syncope results.drawn. When the circulatory changes are great enough, vasovagal syncope results.
Relative dehydration tends to amplify these responses.Relative dehydration tends to amplify these responses.
Excessive activation of the vagal nerve during emotional stress, which is aExcessive activation of the vagal nerve during emotional stress, which is a
parasympathetic overcompensation of a strong sympathetic nervous systemparasympathetic overcompensation of a strong sympathetic nervous system
response associated with stress, can also cause vasovagal syncope because of aresponse associated with stress, can also cause vasovagal syncope because of a
sudden drop in blood pressure and heart rate. Vasovagal syncope affects youngsudden drop in blood pressure and heart rate. Vasovagal syncope affects young
children and women more often. It can also lead to temporary loss of bladder controlchildren and women more often. It can also lead to temporary loss of bladder control
under moments of extreme fear.under moments of extreme fear.
Research has shown that women who have complete transection of the spinal cord can experienceResearch has shown that women who have complete transection of the spinal cord can experience
orgasms through the vagus nerve, which can go from the uterus, cervix and probably theorgasms through the vagus nerve, which can go from the uterus, cervix and probably the
vagina to the brainvagina to the brain
6. Physical and emotionalPhysical and emotional
effectseffects
Activation of the vagus nerve typically leads to a reduction in heart rate, blood pressure,Activation of the vagus nerve typically leads to a reduction in heart rate, blood pressure,
or both. This occurs commonly in the setting of gastrointestinal illness such as viralor both. This occurs commonly in the setting of gastrointestinal illness such as viral
gastroenteritis or acute cholecystitis, or in response to other stimuli, including carotidgastroenteritis or acute cholecystitis, or in response to other stimuli, including carotid
sinus massage, Valsalva maneuver, or pain from any cause, particularly having bloodsinus massage, Valsalva maneuver, or pain from any cause, particularly having blood
drawn. When the circulatory changes are great enough, vasovagal syncope results.drawn. When the circulatory changes are great enough, vasovagal syncope results.
Relative dehydration tends to amplify these responses.Relative dehydration tends to amplify these responses.
Excessive activation of the vagal nerve during emotional stress, which is aExcessive activation of the vagal nerve during emotional stress, which is a
parasympathetic overcompensation of a strong sympathetic nervous systemparasympathetic overcompensation of a strong sympathetic nervous system
response associated with stress, can also cause vasovagal syncope because of aresponse associated with stress, can also cause vasovagal syncope because of a
sudden drop in blood pressure and heart rate. Vasovagal syncope affects youngsudden drop in blood pressure and heart rate. Vasovagal syncope affects young
children and women more often. It can also lead to temporary loss of bladder controlchildren and women more often. It can also lead to temporary loss of bladder control
under moments of extreme fear.under moments of extreme fear.
Research has shown that women who have complete transection of the spinal cord can experienceResearch has shown that women who have complete transection of the spinal cord can experience
orgasms through the vagus nerve, which can go from the uterus, cervix and probably theorgasms through the vagus nerve, which can go from the uterus, cervix and probably the
vagina to the brainvagina to the brain
