Anterior and middle mediastinum

Question 1

Define the borders of the anterior mediastinum

Answer 1

Superior: TTP

Lateral: mediastinal pleura

Anterior: body of the sternum

Posterior: pericardium

Question 2

What is the content of the anterior mediastinum?

Answer 2

Thymus
Fat
Connective tissue
Lymph nodes
Mediastinal branches of internal thoracic vessels
Sternopericardial ligaments

Question 3

The pericardium lies within the middle mediastinum. Describe it

Answer 3

Composed of fibrous and serous pericardium

Fibrous layer made of CT, tough
Cone shaped with the apex continuous with great vessel adventitia, anterior surface bound to sternopericardial ligaments and the base attached to central tendon of diaphragm and small muscular area on LHS
Phrenic nerves and pericadiacophrenic vessels pass though fibrous layer

Serous layer composed of parietal and visceral pleura; between them lies the pericardial cavity
THIN
Continuous at the root of the great vessels, reflections occur 1. superiorly around root of great vessels 2. posteriorly around veins

Question 4

What is the function of the sternopericardial ligament?

Answer 4

Attachement to keep the heart in place in thorax and sac limits cardiac distention

Question 5

Describe the oblique sinus

Answer 5

Lies between the RPV/IVC and RPV/LPV

Question 6

Describe the transverse sinus

Answer 6

Lies between the aorta/pulmonary trunk, anterior to SVC

Clinically used to seperate veins from arteries

Question 7

Describe the arterial supply of the pericardium

Answer 7

Internal thoracic arteries 
Pericardiacophrenic arteries
Inferior phrenic arteries
Thoracic aorta
Musculophrenic artery

Question 8

Describe the venous drainage of the pericardium

Answer 8

Enter azygos veins and internal thoracic and superior phrenic veins

Question 9

Describe the innervation of the pericardium

Answer 9

Vagus nerve
Phrenic nerve
Sympathetic trunk

Question 10

Describe the referred pain from the pericardium

Answer 10

Referred to shoulder/neck
Referred from parietal pleura in serous pericardium

Somatic sensation (pain) is carried by somatic afferent fibres in phrenic nerves

Question 11

Which vessels drain into the right atrium?

Answer 11

Coronary sinus
Vena Cavae
Small cardiac veins

Question 12

Which structures is found within/on the right atrium?

Answer 12

Fossa ovalis- surrounded by prominent margin called limbus fossa ovalis

Right auricle

Smooth and pectinate muscles divided by crista terminalis in RA

Question 13

How do trabeculae carneae differ to pectinate muscles?

Answer 13

Trabeculae carneae irregular muscle tone in ventricles

Pectinate muscle in atria

Question 14

Describe the structure of the septum

Answer 14

Composed of thick-muscular part and thin-membranous part

Question 15

Where can the valve of the foramen oval be seen?

Answer 15

In the left atrium

Question 16

Describe the ascending aorta

Answer 16

Originates in the aortic orifice at base of left ventricle (level with 3rd costal cartilage)

Right and left coronary arteries arise from right and left sinuses respectively

Question 17

Outline the development of the heart

Answer 17

1. Angiogenic clusters form in mesoderm and canalise into early blood vessels
2. 2 blood vessels form in the cardiogenic area known as heart tubes
3. These heart tubes grow and fuse to form a single tube which begins to fold by day 23
4. Resulting in ventricles and outflow tracts positioned anterior to atria and veins
5. Septa grown to divide atria and ventricles

Question 18

State the three layers of heart tissue

Answer 18

Endocardium

Myocardium

Epicardium

Question 19

Describe the fibrous skeleton in the heart and its functions

Answer 19

Framework of 4 fibrous rings of dense CT

Electrical insulation between atria and ventricles
Allows attachment for AV and SL valves