Mediastinum

Question 1

What is the mediastinum?

Answer 1

A region of the thoracic cavity which separates the right and left pleural sacs and is limited on either side by the mediastinal pleura

Question 2

What is the extent of the mediastinum?

Answer 2

Above: Thoracic inlet
Below: Diaphragm
Front: Sternum
Behind: 12 thoracic vertebra

Question 3

How is the mediastinum divided into superior and inferior?

Answer 3

Imaginary horizontal plane from sternal angle to lower border of T-4

Question 4

What are the boundaries of the superior mediastinum?

Answer 4

Anteriorly: Manubrium sterni
Posteriorly: Upper four thoracic vertebra and anterior longitudinal ligament
Superiorly: Thoracic inlet
Inferiorly: Imaginary line
Laterally: Mediastinal pleura

Question 5

What are the regions of the superior mediastinum?

Answer 5

RIP
Retrosternal
Intermediate
Prevertebral

Question 6

What are the contents of the retrosternal region?

Retrosternal = behind manubrium

Answer 6

Sternothyroid & sternohyoid muscles
Thymus gland
Right & Left Brachiocephalic veins + Superior Vena Cava

Question 7

What are the contents of the intermediate region?

Answer 7

Arch of aorta & its 3 branches
Phrenic nerve
Vagus nerve
Cardiac nerve
(PVC)

Question 8

What are the contents of the prevertebral region?

Answer 8

Trachea + paratracheal & tracheobronchial lymph nodes
Oesophagus
Left recurrent laryngeal nerve
Thoracic duct

Question 9

How does infection of the neck spread?

Answer 9

Prevertebral layer of deep cervical fascia extends into superior mediastinum & attached to 4th thoracic vertebra. Infection in neck can pass down into sup. Mediastinum but not lower.

Pretracheal blends with arch of aorta. Neck infection between pretracheal & prevertebral fascia can spread into superior mediastinum- mediastinitis from infection in neck

Question 10

What are the contents of the anterior mediastinum?

Answer 10

RETRO SLAM
Superior & inferior sternopericardial ligaments
Loose areolar tissue
Mediastinal branch of internal thoracic artery
Retrosternal lymph nodes

Question 11

What are the contents of the middle mediastinum?

Answer 11

Ascending aorta
Superior vena cava
Pulmonary trunk
4 pulmonary veins
Arch of azygos vein
Bifurcation of trachea
Phrenic nerve & peri-cardiacophrenic vessels

Question 12

What are the boundaries of the posterior mediastinum?

Answer 12

Anteriorly: Trachea, pulmonary vessels, fibrous pericardium, diaphragm
Posteriorly: Lower 8 thoracic vertebrae
Superiorly: Imaginary plane
Inferiorly: Diaphragm