Superior and Posterior Mediastinum Flashcards
Where does the transverse thoracic plane run from to
The sternal angle to the intervertebral space between T4 and T5
What are the 5 boundaries of the superior mediastinum
- Manubrium
- Bodies of T1-T4
- Thoracic inlet
- Parietal pleura
- Transverse thoracic plane
What are the 7 contents of the superior mediastinum (starting with the most anterior)
- Thymus
- Brachiocephalic veins and SVC
- Arch of aorta
- Trachea
- Oesophagus
- Phrenic and vagus nerves
- Lymphatics
What drains into the great vessels of the superior mediastinum
Head, neck and the upper limb; empties into the SVC
What 3 branches come off the arch of the aorta
- Brachiocephalic trunk
- Left common carotid artery
- Left subclavian artery
What nerve branches from the vagus nerves
The left and right recurrent laryngeal
Where does the right vagus nerve run in the superior mediastinum
It runs anterior to the right subclavian artery
Where does the right recurrent laryngeal nerve run in the superior mediastinum
It loops under the subclavian artery
Where does the left vagus nerve run in the superior mediastinum
It runs between the left common carotid and left subclavian arteries
Where does the left recurrent laryngeal nerve run in the superior mediastinum
It loops under the arch of the aorta; posterior to the ligamentum arteriosum
Is the vagus nerve part of the sympathetic or the parasympathetic nervous system
Parasympathetic
What plexus’ branch from the vagus nerve and where are they located
- Cardiac plexus; deep to aortic arch
- Right pulmonary plexus; right bronchi
- Left pulmonary plexus; left bronchi
- Oesophageal plexus; surface of the oesophagus
What vagal trunk arises from the left and right vagal nerves
- Left vagal nerve forms the anterior vagal trunk
2. Right vagal nerve forms the posterior vagal trunk
What is the root value of the phrenic nerve
Anterior rami C3, C4, and C5
Where does the right phrenic nerve run in the superior mediastinum
Alongside the right brachiocephalic vein, the SVC and the pericardium over the right atrium
Where does the right phrenic nerve pierce the diaphragm
Near the caval opening
Where does the left phrenic nerve run in the superior mediastinum
In between the left subclavian artery and vein, to the left of the aortic arch and onto the surface of the pericardium over the left atrium
Where does the left phrenic nerve pierce the diaphragm
To the left of the pericardium
What information and innervation does the phrenic nerve provide to the superior mediastinum
- Motor innervation to the diaphragm
2. Sensory information to the fibrous pericardium
Where does the trachea run from to
Begins at C6/7 and runs to the carina at T4/5
What muscle is in the posterior section of the trachea
Trachealis muscle
What is the oesophagus a continuation of and where does it begin
The pharynx and at C6
Describe the positioning and route of the oesophagus
Initially it lies to the right of the aorta, then it crosses anteriorly prior to piercing the diaphragm at T10
Where are the 3 constrictions of the oesophagus
- Arch of aorta
- Left bronchus
- Diaphragm
What are the 4 boundaries of the posterior mediastinum
- Transverse thoracic plane
- Bodies of T5-T12
- Pericardium and diaphragm
- Parietal pleura
Where does the descending aorta become the thoracic aorta
At T4/5
Where does the thoracic aorta become the abdominal aorta
After piercing the diaphragm through the aortic hiatus
What do the anterior branches of the thoracic aorta supply
The organs and tissues within the thoracic cavity (oesophagus, pericardium & bronchi)
What do the posterolateral branches of the thoracic aorta supply
The thoracic wall (posterior intercostal arteries)
What are the 5 main branches of the thoracic aorta
- Oesophagus
- Pericardium
- Bronchi
- Thoracic wall
- Diaphragm
What does the azygous venous system drain
The posterior abdominal wall and the thoracic wall
What thoracic wall veins drain directly into the azygous vein
- Right posterior intercostal veins 2-11
2. Right subcostal vein
Where does the 1st right posterior intercostal vein drain
Directly into the right brachiocephalic vein
What thoracic wall veins drain directly into the left brachiocephalic vein
Left posterior intercostal veins 1-4
What veins drain into the accessory hemiazygous vein
The left posterior intercostal veins 5-8; and then into the azygous vein
What veins drain into the hemiazygous vein
The left posterior intercostal veins 9-11 plus the left subcostal vein; and then into the azygous vein
Describe the pathway of the thoracic duct
Ascends up the right hand side of the vertebral column and wraps around the left internal jugular vein
Where does the thoracic duct empty into the venous system
At the junction of the left internal jugular and left subclavian veins; called the left venous angle
What are splanchnic nerves
Nerves coming from the sympathetic chain providing innervation to the abdominal viscera
What is the root value of the greater splanchic nerve
T5-T9 ganglia
What is the root value of the lesser splanchnic nerve
T10-T11 ganglia
What is the root value of the least splanchnic nerve
T12 ganglion
What ganglia does the greater splanchnic nerve supply
- Coeliac
2. Superior mesenteric
What ganglia does the lesser splanchnic nerve supply
- Superior mesenteric
2. Aorticorenal
What ganglia does the least splanchnic nerve supply
Aorticorenal
At what vertebra does the IVC pierce the diaphragm and what is the opening called
T8 and the caval opening
At what vertebra does the oesophagus and vagal trunk pierce the diaphragm, and what is the opening called
T10 and the oesophageal hiatus
At what vertebra does the aorta, thoracic duct and azygous vein pierce the diaphragm, and what is the opening called
T12 and the aortic hiatus
At what vertebra do the greater and lesser splanchnic nerves pierce the diaphragm, and where do they pierce it
T12 and through openings in the crura
At what vertebra does the least splanchnic nerve and the sympathetic trunk pierce the diaphragm, and where do they pierce it
T12 and behind the medial acruate ligament
