Middle Mediastinum

Question 1

What is the function of the mediastinum?

Answer 1

Fibrous and serous layers that surround the heart so it can expand and contract. It also supports and stabilises the heart.

Question 2

Describe the structure of the fibrous pericardium

Answer 2

defines the middle mediastinum

surrounds the heart and the great vessels

Question 3

What are the attachments of the fibrous pericardium?

Answer 3

attaches superiorly to the roots of the great vessels

attaches inferiorly to the central tendon of the diaphragm halting the desert of the diaphragm during inspiration

Question 4

what are the attachments of the serous pericardium?

Answer 4

attaches to the internal surface of the fibrous layer and is continuous around the roots of the great vessels

Question 5

What is the position of the transverse pericardial sinus?

Answer 5

it separates the great arteries and veins
Anterior- aorta and the pulmonary trunk
posterior- superior vena cava and left auricular appendage of the left atrium

Question 6

what is the position of the oblique pericardial sinus?

Answer 6

potential space behind the left atrium

the posterior aspect of the heart

Question 7

What clinical conditions can affect the pericardium?

Answer 7

• Cardiac tamponade- when increased fluid puts pressure on the heart
• pericarditis- inflammation of the pericardium

Question 8

What forms the anterior/ sternocostal surface of the heart?

Answer 8

Right atrium, right ventricle, left ventricle and left auricular appendage

Question 9

What forms the inferior/diaphragmatic surface of the heart?

Answer 9

left and right ventricles

Question 10

What chamber forms the base of the heart?

Answer 10

left atrium

Question 11

What forms the right border of the heart?

Answer 11

the right atrium

Question 12

What forms the left border of the heart?

Answer 12

the left atrium and the left auricular appendage

Question 13

What forms the apex? Where can you locate the apex?

Answer 13

• the left ventricle

- the 5th left intercostal space, mid clavicular line

Question 14

What are the major relations on either side of the heart?

Answer 14

pleura and lungs (L+R) and the phrenic nerves

Question 15

What are the major relations behind the heart?

Answer 15

oesophagus and descending aorta

Question 16

which structures are associated with the R atrium of the mediastinum?

Answer 16

SVC, IVC and arch of the azygos

Question 17

Which structures are associated with the left ventricle of the mediastinum?

Answer 17

L common carotid artery, L subclavian artery, aortic arch, thoracic aorta

Question 18

How do both phrenic nerves enter the superior mediastinum?

Answer 18

between the veins and arterial plexuses, posterior to the brachiocephalic veins

Question 19

What is the course taken by the right phrenic nerve?

Answer 19

right side of SVC, anterior to the root of the right hilum, right of the IVC to underside of Diaphragm at T8

Question 20

What is the course of the left phrenic nerve?

Answer 20

anteriorly to the first part of SC artery posteriorly to the SC vein, crosses the aortic arch and passes lateral to the vagus nerve,

Question 21

Explain why irrigation of the phrenic nerve will result in referred pain to the shoulder.
Give an example.

Answer 21

-Phrenic nerve C3,4,5 (keeps the diaphragm alive), also sensory from: central tendon of diaphragm and related parietal pleura and underlying peritoneum, mediastinal pleura, pericardium
-Supraclavicular C3,4
-hence structures with a sensory supply via the phrenic will refer pain to the shoulder tip
Example- gall bladder refers pain to R shoulder tip