Thorax 9: Posterior Mediastinum Flashcards
What vertebral levels define the posterior mediastinum?
T4/5 and posterior attachment of the diaphragm at T12
what are the levels that define the thoracic aorta?
from T4/5/angle of louis at 2nd costal cartilage to the aortic hiatus at T12
how does the thoracic aorta pass through the diaphragm
runs between the crura and behind the median arcuate ligament
define the relationship of the thoracic aorta to the vertebral bodies
initially lies on the left of vertebral bodies
moves to midline in lower thorax
Name the branches of the aorta
posterior intercostal arteries bronchial arteries oesophageal arteries subcostal arteries small branches to diaphragm and pericardium
how many posterior intercostal arteries are there and what do they supply?
9 arteries that supply lower 9 intercostal spaces from ribs 3-11
what artery supplies the first 2 intercostal spaces and what does it arise from
superior intercostal artery arising from the costocervical trunk of the subclavian arteries
where do the anterior intercostals arise from?
internal thoracic arteries arising from the subclavian arteries
how many bronchial arteries are there?
2 left and 1 right
what part of the oesophagus is supplied by the thoracic aorta?
middle 1/3 of the oesophagus
what drains the part of the oesophagus supplied by the thoracic aorta?
azygous vein
what artery supplies the posterior abdominal wall
subcostal arteries that lie inferior to the 12th rib
what is the vascular supply of the superior 1/3 of the oesophagus
arterial from inferior thyroid arteries
venous to brachiocephalic veins
what is the nervous supply of the superior 1/3 of the oesophagus?
recurrent laryngeal nerves of the vagus nerve
the deep cervical nodes drain which part of the oesophagus?
superior 1/3
what part of the oesophagus is made up of striated muscle only
superior 1/3
which part of the oesophagus is made up of mixed muscle
middle 1/3
what part of the oesophagus is supplied by the oesophageal plexus?
middle and inferior 1/3s
the tracheobronchial nerves drain which part of the oesophagus?
middle 1/3
what is the vascular supply of the inferior 1/3 of the oesophagus
arterial - left gastric artery
venous - left gastric vein and portal vein
what is the lymphatic drainage of the inferior 1/3 of the oesophagus?
coeliac nodes
what are the relationships of the oesophagus in the superior mediastinum?
posterior to trachea
right of the aorta
what are the relationships in the inferior mediastinum of the oesophagus?
swings forward and to the left
anterior to the aorta
leaves at T10
what forms the cardiac sphincter?
the oblique entry of the oesophagus into the stomach
resting tone of smooth muscle
prevents gastric reflux
what is significant about the submucosal veins
form an anastomoses between the venous drainage of the lower and middle 1/3s
connects the portal and systemic circulations
what is the distance to the upper oesophageal sphincter and what is the anatomical landmark
17cm
junction of oesophagus with pharynx
name the 4 oesophageal sphincters
upper oesophageal sphincter
arch of the aorta
left main bronchus
lower oesophageal sphincters
what is the distance to the 3rd oesophageal sphincter
28 cm
what is the distance to the last oesophageal sphincter
43 cm
what problems are caused by the oesophageal sphincters
blockage more likely
passage of instruments more difficult
slow down passage of caustic substances
what is found posterior to the oesophagus
thoracic duct and thoracic aorta inferiorly
at what point does the thoracic duct cross the oesophagus
T4/5
where does the thoracic duct receive lymph from?
left
jugular lymph trunk of head and neck
subclavian lymph trunk of upper limb
bronchomediastinal trunk of left thorax
where are posterior mediastinal nodes found
behind the heart near the oesophagus
describe the route of lymph from pulmonary nodes
bronchopulmonary - inferior and superior tracheobronchial - paratrancheal - bronchomediastinal lymph trunks
describe the route of lymph from the posterior mediastinal nodes
paratracheal - bronchomediastinal
which node groups drain straight into the bronchomediastinal trunks
parasternal/internal thoracic
anterior mediastinal
what does the azygous vein drain
posterior thorax wall
where does the azygous vein begin?
begins from the lumbar and subcostal veins or a direct branch of the IVC
where does the azygous vein lie on the vertebral column?
midline or to the right
where does the azygous vein join the SVC
2nd right costal cartilage
what vessels does the azygous vein receive?
veins equivalent to branches of the descending thoracic aorta
what are the parts of the hemiazygous veins
lower and upper accessory hemiazygous veins
what is the route of the lower hemiazygous vein
connects with left renal vein
passes through or behind left crus of diaphragm
crosses to azygous at T9
what is the route of the upper accessory hemiazygous vein?
descend from the 4th intercostal space and crosses to azygous at T8
what can cause pain on swallowing
oesophageal indentations caused by arthritic osteophytes
what causes portal hypertension
cirrhotic liver disease
what causes oesophageal varices
escaping of blood from portal vein to azygous vein via the submucosal portosystemic anastomosesin portal hypertension
what is a danger of thoracic surgery
damage to thoracic duct
leakage of lymph
chylothorax
