posterior mediastinum Flashcards
prominent vessels in posterior mediastinum
descending aorta, oesophagus, vagus nerve
ligamentum arteriosum - remnant left over of foetal pulmonary bypass
vagus to left recurrent laryngeal nerve - control most skeletal muscles of larynx
recognise
phrenic, vagus nerves, hylem (bronchus, pulmonary veins, pulmonary arteries), trachea, oseophagus, thoracic duct
pulmonary ligament
part of hylem allowing expansion of right lung
right lung
azygos veins (more R than L)
hylem
phrenic anterior, alongside pericardium, vagi posterior
entire diagram at T3 from A
slide 5; no subclavian artery so only braciocephalic trunk; left winds around aorta; right winds around subclavian so right recurrent laryngeal nerve not present at T3; left recurrent laryngeal nerve winding around ligamentum arteriosum
contents of posterior mediastinum
remove pericardium; oesophagus, (larynx top of airway, pharynx top of GIT); descending aorta, thoracic duct, Azygos venous system
Posterior mediastinal lymph nodes
Thoracic sympathetic trunks
Splanchnic nerves
oesophagus
Begins at level of C7 vertebra Ends at stomach, level of T11 vertebra Bends more anteriorly at T7 Is right of aorta above T7 Deviates to left at T7 Progressively anterior to aorta below T7 Passes through diaphragm at T10 Has constrictions at four locations
trachea
C6
constrictions of oesophagus
at C7 (junction of oesophagus with pharynx), where arch of aorta becomes descending aorta, where compressed by L main bronchus, where passes through diaphragm
arteries of oesophagus
intercostal spaces at top have different supply to bottom (aorta doesn’t ascend as high as ICS 1 and 2 - posterior intercostal arteries receive supply from subclavian arteries - supreme intercostal artery); others supplied by descending aorta
azygos
thoracic duct; left and right brachioceophalic merge to form SVC; left to right side, ascends and drains into SVC; azygos smaller than aorta; on left: accessory hemiazygos and hemiazygos
azygos venous system
variable; Drains posterior wall of chest and upper abdomen + posterior mediastinal organs
Usually accessory hemiazygos (upper) and hemiazygos (lower) veins on left cross thoracic vertebral bodies to join single axygos vein on right
Azygos vein arches over right lung root to enter SVC just above right atrium
nerves in inferior mediastinum
phrenics (anterior to lung roots), vagi (posterior to lung roots - plexus - follow oesophagus to abdomen), sympathetic trunks (each side of posterior mediastinum)
vagus nerves
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
sympathetic trunks - none for preaortic ganglia which serve heart
Receive branches from spinal nerves T1 - L2
Distribute sympathetic nerves to smooth muscle and glands throughout body
Nerves to body wall synapse in ganglia of trunks
Nerves to internal organs (viscera) synapse in local ganglia
Also bring pain fibres back to CNS from viscera
Fibres from lower T5 - T12 reach abdomen in bundles called splanchnic nerves
stellate ganglion
trunk associated with T1 spinal cord segment
T5-T9
greater splanchnic nerve
T10-T11
lesser splanchnic nerve
T12
least splanchnic nerve
thoracic duct
Lymph duct returning lymph from lower limbs, pelvis, abdomen & left thoracic wall to blood
Begins below diaphragm at cisterna chyli
Starts between oesophagus and aorta on right, runs along spinal column
Crosses behind oesophagus to left side between T7 and T4
Drains into junction of left subclavian and left internal jugular veins (to form left brachiocephalic vein)
