The heart and mediastinum

Question 1

Which 2 veins join to form the brachiocephalic veins?

Answer 1

Internal jugular veins and subclavian veins

Question 2

The brachiocephalic veins are formed behind what?

Answer 2

The sternoclavicular joint

Question 3

The brachiocephalic veins join to form what?

Answer 3

Superior vena cava

Question 4

Where is the SVC formed?

Answer 4

Behind the right costal cartilage of rib 2

Question 5

Which procedure involves both the venous system and liver biopsy?

Answer 5

Transjugular liver biopsy

Question 6

What are the 3 main arteries that branch off the aortic arch in the superior mediastinum?

Answer 6

Brachiocephalic trunk

Left common carotid artery

Left subclavian artery

Question 7

The ligamentum arteriosum is a remnant of what?

Answer 7

Ductus arteriosus

Question 8

Which 2 structures did the ductus arteriosus join together?

Answer 8

Pulmonary trunk and aortic arch

Question 9

What was the function of the ductus arteriosus?

Answer 9

Allowed blood to bypass the lungs during embryological development

Question 10

What can happen if the ductus arteriosus fails to close after birth?

Answer 10

It results in a patent ductus arteriosus, which allows for mixing of low oxygenated blood from the pulmonary trunk with high oxygenated blood in the aorta, therefore decreasing the oxygen content of the blood heading towards systemic circulation

Question 11

The internal thoracic arteries branch off from which arteries?

Answer 11

Subclavian arteries

Question 12

The internal thoracic arteries can be grafted for use in which procedure? Why are these arteries particularly beneficial for this procedure?

Answer 12

CABG – coronary artery bypass graft

They resist atherosclerotic plaque build up

Question 13

What happens to the thymus gland after childhood?

Answer 13

Atrophies

Question 14

What surrounds the heart?

Answer 14

Pericardial sac

Question 15

The fibrous pericardium is attached to what inferiorly?

Answer 15

Central diaphragmatic tendon

Question 16

What are 2 things that are most likely to cause a blockage of the SVC?

Answer 16

Extrinsic compression by a tumour

Metastasis to mediastinal lymph nodes

Question 17

Which levels of the sympathetic chain carry fibres to the heart?

Answer 17

T1 – T4

Question 18

Why does cardiac pain occur in the T1 – T4 dermatomes, mainly on the left?

Answer 18

Cardiac visceral sensory fibres travel back to the CNS with the sympathetic nerves T1 – T4

Question 19

What 2 layers is the pericardium composed of?

Answer 19

Fibrous pericardium

Serous pericardium

Question 20

The parietal layer of the serous pericardium lines what?

Answer 20

The inside of the fibrous pericardium

Question 21

The visceral layer of the serous pericardium lines and forms what?

Answer 21

The heart and forms the epicardium

Question 22

What innervates the fibrous pericardium?

Answer 22

Phrenic nerve

Question 23

Describe how a haemopericardium can lead to cardiac tamponade?

Answer 23

In a haemopericardium, blood accumulates in the pericardial sac. The fibrous pericardium is relatively inelastic, so blood in the sac can compress the heart and prevent it from being able to fill properly during diastole due to external compression – this is cardiac tamponade

Question 24

What are the 2 sinuses of the heart?

Answer 24

Transverse pericardial sinus

Oblique pericardial sinus

Question 25

What clinical manoeuvre can the transverse pericardial sinus be used for?

Answer 25

Can be used during cardiac surgery (e.g. coronary artery bypass graft) to pass a surgical clamp around the aorta and pulmonary trunk to control blood flow while on a heart-lung machine