Thorax 8 - Posterior Mediastinum Flashcards
Describe how the physiological cardiac sphincter works.
Contraction of the diaphragm squeezes the oesophagus closed, preventing back flow into the oesophagus
What is the name given to the anastomosis between the portal and systemic circulations?
Porto-systemic/Portocaval
What are the 3 constrictions in the oesophagus caused by?
Arch of aorta
Left main bronchus
Left atrium of heart
List the order of lymph drainage in the pulmonary region.
Pulmonary —> Bronchopulmonary —> Inferior and Superior Tracheobroncheal —> Paratracheal —> Bronchomediastinal
Where does lymph from posterior mediastinal nodes drain to?
Paratracheal
Where does lymph from anterior mediastinal nodes and parasternal nodes drain to ?
Bronchomediastinal
Name the 5 birds that cross the diaphragm.
Azy-goose Hemiazy-goose Va-goose Oesopha-goose Thoracic Duck
Boundaries of the superior mediastinum:
Thoracic inlet
Plane b/n sternal angle & T4/5
Boundaries of the inferior mediastinum:
Plane b/n sternal angle T4/5
Thoracic outlet
Boundaries of the posterior mediastinum:
Posterior to pericardial sac & diaphragm
T4/5 vertebral level
T12 vertebral level
The aortic hiatus in the diaphragm lies between the crura and ………… the median arcuate ligament.
Behind
Between which landmarks in the posterior mediastinum does the descending thoracic aorta lie?
T4/5 vertebral level aka 2nd CC
Aortic hiatus @ T12
What do the oesophageal arteries supply?
Middle third of the oesophagus
What do the 9 posterior intercostal arteries supply?
Lower 9 intercostal spaces (3 - 11)
Which arteries lie inferior to the 12th rib and supply the posterior abdominal wall?
Subcostal arteries
How many bronchial arteries are there on each side of the descending thoracic aorta?
2 left
1 right
What is the length and width of the oesophagus?
25cm long
2cm diameter
Where does the oesophagus lie in relation to the trachea and the aorta in the superior mediastinum?
Posterior to the trachea
Right of the aorta
Where does the oesophagus lie in relation to the aorta just prior to piercing the diaphragm in the posterior mediastinum?
Anterior
At what vertebral level does the oesophagus pierce the diaphragm?
T10
At what vertebral level does the aorta pierce the diaphragm via the aortic hiatus?
T12
What type of muscle is present in the oesophageal walls?
Upper third = striated (swallowing is voluntary)
Middle third = mixed
Lower third = smooth muscle
Where does the crico-pharyngeal sphincter lie and what is its purpose?
Between the pharynx and the oesophagus
Prevents air being sucked into the stomach during inhalation
What is the function of the cardiac sphincter?
To prevent gastric reflux
Which diaphragmatic crus does the oesophagus pass through?
Right crus
What is the arterial supply, venous drainage, nervous supply and lymph drainage of the superior (cervical) third of the oesophagus (beginning at C6)?
- Arterial supply from inferior thyroid arteries
- Venous drainage to brachiocephalic veins
- Nerve supply from branches of the vagus nerves (recurrent laryngeal nerves)
- Lymphatics drain to deep cervical nodes
What is the arterial supply, venous drainage, nervous supply and lymph drainage of the middle (thoracic) third of the oesophagus?
- Arterial supply direct from thoracic aorta and bronchial arteries
- Venous drainage to azygous system (systemic)
- Nerve supply from oesophageal plexus (vagus & sympathetic)
- Lymphatics drain to tracheobronchial nodes
What is the arterial supply, venous drainage, nervous supply and lymph drainage of the inferior (abdominal) third of the oesophagus?
- Arterial supply from the left gastric artery
- Venous drainage to left gastric veins and therefore to portal vein
- Nerve supply from branches of the oesophageal plexus (vagus & sympathetic)
- Lymphatics drain to left gastric and coeliac nodes
What is special about the submucosal veins?
Form an anastomosis between middle and inferior thirds of the oesophagus and therefore is a porto-systemic or portocaval anastomosis
How can cirrhotic liver disease cause fatal haemorrhage?
Raises portal venous pressure, causing portal hypertension, dilating first the submucosal and then the azygos vein and making the latter tortuous, leading to oesophageal varicies –> fatal haemorrhage
Where do the 4 oesophageal constrictions occur?
Upper oesophageal sphincter 17cm
Arch of aorta
Left main bronchus at 28cm
Diaphragm (lower oesophageal sphincter) at 43cm
(Indentation rather than constriction of left atrium
What structures lie anterior to the oesophagus?
Trachea Right pulmonary artery Left main bronchus LA Diaphragm
What structure lies to the right of the oesophagus?
Azygous vein
What structure lies to the left of the oesophagus?
Thoracic aorta
What is the thoracic duct a continuation of?
Cisternae chyli
What two structures does the thoracic duct lie between?
Azygous vein
Aorta
At what vertebral level does the thoracic duct cross to ascend the oesophagus on its left side?
T4/5
What will damage of the thoracic duct lead to?
Leaking of lymph –> chylothorax
List the 3 types of ‘tracheal’ lymph nodes.
Superior tracheobronchial
Inferior tracheobronchial
Paratracheal (alongside the trachea)
Where are the anterior mediastinal lymph nodes clustered?
BCV
Where do the posterior mediastinal lymph nodes lie?
Behind the heart and adjacent to the oesophagus
Where do the thoracic duct and the azygous vein peirce the diaphragm?
At the aortic hiatus - T12
List the pattern of lymph drainage of the thorax.
Pulmonary
Bronchopulmonary
Inf. and Sup. Tracheobroncial Post. Mediastinal
Paratracheal Parasternal Ant. Mediastinal
Bronchomediastinal Lymph Trunks
Which 3 lymph trunks does the thoracic duct receive before entering the BCV?
(Left) Jugular Lymph Trunk (Head & Neck)
(Left) Subclavian Lymph Trunk (UL)
(Left) Bronchomediastinal Trunk (Left Thorax)
Which 3 lymph trunks does the thoracic duct receive before entering the LBCV?
(Left) Jugular Lymph Trunk (Head & Neck)
(Left) Subclavian Lymph Trunk (UL)
(Left) Bronchomediastinal Trunk (Left Thorax)
Which 3 lymph trunks does the right lymphatic duct receive before entering the RBCV?
(Right) Jugular Lymph Trunk (H & N)
(Right) Subclavian Lymph Trunk (UL)
(Right) Bronchomediastinal Trunk (Right thorax)
What structures does the azygous vein drain?
Posterior thoracic walls
Part of the abdomen
From which veins does the azygous originate and which vein does it drain into?
Originates: Subcostal & Lumbar veins
Drains to: SVC
Where does it drain into the SVC?
2nd right CC
Which important vein does the hemi-azygous (lower) have connections with?
Left renal vein
At which vertebral level does the hemi-azygous (lower) vein cross to the RHS?
T9
At what vertebral level does the accessory hemi-azygous (upper) cross to the RHS?
T8
From which intercostal space does the accessory hemi-azygous (upper) vein descend from?
4th intercostal space
