Week 5 - The Mediastinum

Question 1

What are the boundaries of the mediastinum?

Answer 1

Anteriorly – Sternum, Posteriorly – Vertebral Column, Superiorly – Thoracic Inlet, Inferiorly – Diaphragm, On each side – Mediastinal pleura

Question 2

How is the mediastinum subdivided?

Answer 2

Divided into Superior Mediastinum and Inferior Mediastinum (3 parts: Anterior, Middle, Posterior)

Question 3

What are the boundaries of the Superior Mediastinum?

Answer 3

Anteriorly – Manubrium sterni, Posteriorly – Upper 4 thoracic vertebrae, Superiorly – Plane of the thoracic inlet, Inferiorly – imaginary plane passing through sternal angle & T4, On each side – Mediastinal pleura

Question 4

List the contents of the Superior Mediastinum.

Answer 4

• Trachea & Oesophagus
• Arch of aorta
• Brachiocephalic artery
• Left common carotid artery
• Left subclavian artery
• Upper half of superior vena cava
• Right & left brachiocephalic veins
• Left superior intercostal veins
• Vagus nerve
• Phrenic nerves
• Left recurrent laryngeal nerve
• Thymus gland
• Thoracic duct
• Paratracheal lymph nodes
• Brachiocephalic lymph nodes
• Tracheobronchial lymph nodes

Question 5

What is the course of the Right Recurrent Laryngeal Nerve?

Answer 5

Hooks around right subclavian artery and ascends in trachea-oesophageal groove

Question 6

What is the course of the Left Recurrent Laryngeal Nerve?

Answer 6

Hooks around the aortic arch and ascends in trachea-oesophageal groove

Question 7

What do the Recurrent Laryngeal Nerves innervate?

Answer 7

Laryngeal mucosa below fissure of glottis and all laryngeal muscles except cricothyroid

Question 8

What forms the Brachiocephalic veins?

Answer 8

Formed by Internal jugular veins and Subclavian veins

Question 9

Where do the Brachiocephalic veins join to form the superior vena cava?

Answer 9

Behind the lower border of the first right costal cartilage

Question 10

What does the Superior Vena Cava collect blood from?

Answer 10

Veins of upper half of the body

Question 11

What are the boundaries of the Anterior Mediastinum?

Answer 11

Anteriorly – body of sternum, Posteriorly – pericardium, Superiorly – imaginary plane, Inferiorly – superior surface of diaphragm, On each side – mediastinal pleura

Question 12

List the contents of the Anterior Mediastinum.

Answer 12

• Sternopericardial ligaments
• Lymph nodes with lymphatics
• Lowest part of the thymus

Question 13

What are the contents of the Middle Mediastinum?

Answer 13

• Heart enclosed in pericardium
• Ascending aorta
• Pulmonary trunk & 2 branches
• Upper part of inferior vena cava
• Lower half of superior vena cava
• Terminal part of the azygos vein
• Phrenic nerves
• Bifurcation of trachea into right & left principal bronchi

Question 14

What are the boundaries of the Posterior Mediastinum?

Answer 14

Posterior to heart & pericardium, Anterior to vertebrae T5-T12, On each side – mediastinal pleura

Question 15

List the contents of the Posterior Mediastinum.

Answer 15

• Oesophagus
• Descending aorta & its branches
• Azygos vein
• Hemiazygos vein
• Accessory hemiazygos vein
• Vagi nerves
• Splanchnic nerves
• Posterior mediastinal lymph nodes
• Thoracic duct