Superior and Posterior Mediastinum

Question 1

What are the borders of the Superior Mediastinum?

Answer 1

1. Superior–> Thoracic Inlet
2. Inferior–> Level T4
3. Anterior–> Manubrium of Sternum
4. Posterior–> Vertebral bodies T1-T4
5. Lateral–> Pleura of Lungs

Question 2

What are the contents of the Superior Mediastinum?

Answer 2

1. Great Arteries and Vein
2. Oesophagus
3. Trachea
4. Vagus and Phrenic Nerves
5. Thoracic Duct

Question 3

What are the branches of the Arch of Aorta?

Answer 3

1. Descending Aorta
2. Brachiocephalic–> Branches into the right subclavian and right common carotid
3. Left Common Caortid
4. Left Subclavian

Question 4

Where does the Superior Vena Cava bifurcate into the right and left brachiocephalic veins?

Answer 4

At the level of Costal Cartilage 1

Question 5

Where does the Azygous vein join up with the Superior Vena Cava?

Answer 5

At level T4, level of Costal Cartilage 2

Question 6

Where doe the Superior Vena Cava enter the right atrium of the heart?

Answer 6

At the level of Costal Cartilage 3

Question 7

Where does the right vagus nerve run?

Answer 7

Runs parallel to the trachea, passing anteriorly to the origin of (hooks over) the right subclavian artery and gives of the right recurrent laryngeal nerve which hooks under the right subclavian artery to supply the muscles of the larynx–> can be affected by conditions at the apex of the lung e.g. Pancoasts Tumour

Question 8

Where does the left vagus nerve run?

Answer 8

Enters the superior mediastinum between the left common carotid and left subclavian arteries, passes over the aortic arch and gives off the left recurrent laryngeal nerve which hook under the the arch of aorta to supply the muscles of the larynx–> can be affected by enlarged lymph nodes

Question 9

Where does the Right Phrenic Nerve run?

Answer 9

On the right wall of the Superior Vena Cava and directly to the right side of the fibrous pericardium

Question 10

Where does the Left Phrenic Nerve run?

Answer 10

Passes over the left side of the arch of aorta and the left pulmonary artery, then descends on the pericardium over the left ventricle to the diaphragm near the cardiac apex

Question 11

What are the borders of the posterior mediastinum?

Answer 11

1. Lateral–> Mediastinal Pleura
2. Anterior–> Pericardium
3. Posterior–> T5-T12 vertebrae
4. Superior–> Level T4
5. Inferior–> Diaphragm

Question 12

What are the contents of the posterior mediastinum?

Answer 12

1. Great Arteries and Vein
2. Oesophagus
3. Trachea
4. Vagus and Phrenic Nerves
5. Thoracic Duct
6. Sympathetic Chain

Question 13

What is the arterial supply to the posterior mediastinum?

Answer 13

1. Posterior Intercostal arteries–> 1st and 2nd arise from the subclavian, 3rd onwards from the descending aorta
2. Oesophagal Arteries to Oesophagus
3. Superior Phrenic Arteries to Superior aspect of diaphragm

Question 14

What is the venous drainage of the posterior mediastinum?

Answer 14

The Azygous system

Question 15

Describe the Azygous system

Answer 15

Right Side: Azygous Vein

Left Side: Accessory Hemiazygous (T4-T8) and Hemiazygous (T9-T12)

Question 16

Describe the lymphatic drainage of the posterior mediastinum

Answer 16

Via the Thoracic Duct, starting from the Cisterna Chyli at L2–> receives drainage from intercostal nodes, parasternal nodes and diaphragmatic nodes. Right side drains into the jugular trunk and right subclavian, left side drains directly into the left subclavian

Question 17

Where is the Sternal Origin of the Diaphragm?

Answer 17

Level T8

Question 18

What passes through the Diaphragm at Level T8?

Answer 18

Inferior Vena Cava and Right Phrenic Nerve

Question 19

Where is the Vertebral Origin of the Diaphragm?

Answer 19

Level T10

Question 20

What passes through the diaphragm at level T10?

Answer 20

Vagus Nerves and Oesophagus

Question 21

Where is the Costal Origin of the diaphragm?

Answer 21

Level T12

Question 22

What passes through the diaphragm at Level T12?

Answer 22

Aorta, Thoracic Duct and Azygous Vein

Question 23

What is the nervous supply of the Diaphragm?

Answer 23

Phrenic Nerves from C3,4,5

Question 24

What is the Arterial Supply of the Diaphragm?

Answer 24

1. Inferior Phrenic Arteries
2. Superior Phrenic Arteries
3. Musculophrenic Arteries
4. Pericardiophrenic Arteries

Question 25

Where is the oesophagus narrowed?

Answer 25

1. Cricopharyngeus (15cm)
2. Aortic Arch and Left Main Bronchus (25cm)
3. Squamocolumnar Junction (40cm)

Question 26

What is the arterial supply of the oesophagus?

Answer 26

1. Cervical Portion–> Inferior Thyroid Artery
2. Thoracic Portion–> Bronchial and Oesophageal branches of Thoracic Aorta
3. Abdominal Portion–> Left Phrenic Artery and Left Gastric Artery

Question 27

What is the Venous Drainage of the Oesophagus?

Answer 27

Oesophageal Veins drain to Azygous in the Thorax and the Inferior Thyroid Vein in the neck

Question 28

What is the Nervous Supply of the Oesophagus?

Answer 28

Vagus Nerve and the Cervical andThoracic Sympathetic Trunk