thoracic regional anatomy Flashcards
vagus and phrenic nerves: describe the origin, course and distribution of the vagus and phrenic nerves
what are phrenic nerves formed in
cervical plexus from C3, C4 and C5
what do motor phrenic nerves innovate
diaphragm
what 4 structures do sensory phrenic nerves innovate
central tendon to diaphragm, mediastinal pleura, pericardium, peritoneum of central diaphragm
what phrenic nerve reaches diaphragm
right and left separately
what 3 structures does the right phrenic nerve lie on the surface of
right brachiocephalic vein, superior vena cava, right side of heart and pericardium in front of lung root
where do vagus nerves lie in relation to common carotids
lateral
where does left vagus pass in relation to aortic arch
anterior
where does left phrenic cross the vagus in relation to aortic arch
more anteriorly
where does left phrenic descend
in front of lung root
where does left vagus cross in relation to root lung
behind
what does left vagus give off
left recurrent laryngeal nerve
where does the left recurrent laryngeal nerve recur around
ligamentum arteriosum and aortic arch
where does the left recurrent laryngeal nerve break up into many branches
round oesophagus
where does the right vagus nerve lie
on trachea
where does right vagus cross in relation to root lung
behind
what does right vagus give off
right recurrent laryngeal nerve
where does the right recurrent laryngeal nerve recur around
right subclavian artery
where does the right recurrent laryngeal nerve break up into many branches
round oesophagus
what type of nerve are phrenic nerves
somatic, so no autonomic function or visceral distribution
what do phrenic motor fibres supply
skeletal muscle of diaphragm
what do phrenic sensory fibres supply
central diaphragm, its plueral covering, mediastinal pleura, pericardium, peritoneum on inferior surfacr of central diaphragm
pulmonary plexuses
left vagus nerve, right vagus nerve, anterior pulmonary plexus, posterior pulmonary plexus
effect of parasympathetic efferents (vagus) on heart rate and diameter of coronary arteries
decrease heart rate via pacemaker tissue and constrict coronary arteries
what do parasympathetic afferents (vagus) relay
blood pressure and chemistry information from heart
where does vagus nerve arise from and leave skull through
arises from medulla and leaves skull through jugular foramina
where does the vagus nerve descend in the neck
posterolateral to common carotid artery
where does left vagus cross
anterior to aortic arch then posterior to left lung root
where does right vagus pass
posterior to right lung root
where do both vagi form a plexus
round oesophagus
what do the vagi separate to form
anterior and posterior oesophageal/gastric nerves
what are the branches to chest and abdomen
parasympathetic, with large sensory (enteroceptor) content from gut and lungs
difference between parasympathetic and sympathetic
parasympathetic provide no autonomic supply to body wall (e.g. arterioles and sweat glands)
recurrent laryngeal branch of vagus nerve
not parasympathetic - runs back up neck to supply most skeletal muscles of larynx
vagi in posterior mediastinum
mainly right vagus contributes to oesophageal plexus; nerves also acquire many sympathetic fibres
vagi in posterior mediastinum: inferior continuation
posterior oesophageal nerve, taking right vagal fibres through diaphragm to abdominal viscera
vagi in posterior mediastinum: left vagus
provides fibres to oesophageal plexus then continues as anterior oesophageal nerve
positions of phrenic and vagus nerves and sympathetic trunks in superior mediastinum
slide 42
nerves in inferior mediastinum
phrenics (anterior to lung roots), vagi (posterior to lung roots - plexus - follow oesophagus to abdomen)
vagus nerves inferior mediastinum
chest and abdomen are parasympathetic; large sensory from gut and airways, recurrent laryngeal nerve not parasympathetic - runs back up neck to supply most skeletal muscles of larynx
left vagus
becomes anterior vagal trunk
right vagus
becomes posterior vagal trunk
