Cardiac Anatomy

Question 1

From which of the aortic sinuses do the coronary arteries arise?

Answer 1

RCA from the anterior coronary sinus LCA from the left coronary sinus The right sinus is non-coronary

Question 2

From which coronary arteries are the SAN, AVN and PIVA supplied? Outline the important anastomoses

Answer 2

SAN 60% from RCA, 40% from LCA AVN 80% from RCA, 20% from LCA PIVA 60% from RCA, 40% from LCA Anatomises between the PIVA and AIVA, PIVA and left circumflex

Question 3

Describe the venous drainage of the heart

Answer 3

The main vessel which drains the heart is the coronary sinus, situated within the coronary sulcus. The sinus drains into the right atrium.

Question 4

Through what mechanism is back flow through the tricuspid valves prevented?

Answer 4

The contraction of the papillary muscles, prior to ventricular contraction, causes the chorda tendinae to become taut. This causes the tricuspid valves to close, preventing back flow of the from the ventricles in to the atria during contraction.

Question 5

Describe the consequences of damage to the papillary muscles

Answer 5

The papillary muscles may become damaged following ischaemic periods, leading to myocardial infarction. The muscles may cease to function and allow back flow of blood between the ventricles and the atria.

Question 6

Describe the borders of the mediastinum

Answer 6

Upper: Thoracic inlet/

Anterior: Sternum

Inferior: Diaphragm

Posterior: Thoracic vertebrae

• The mediastinum is divided into superior and inferior portions at vertebral level T4/T5

Question 7

Describe the contents of the superior mediastinum

Answer 7

Vessels: SVC, azygous vein, aorta Nerves: Left recurrent laryngeal, phrenic, vagus Thoracic duct, thyroid glands, trachea, oesophagus

Question 8

Describe the contents of the anterior mediastinum

Answer 8

Small portion (lower lobes) of the thyroid gland in children, adipose tissue, lymphatics, loose connective tissue

Question 9

Describe the contents of the middle mediastinum

Answer 9

The heart: Fibrous pericardium, parietal membranous pericardium, visceral pericardium, myocardium, endocardium Great vessels: Aorta, SVC, pulmonary trunk

Question 10

Describe the contents of the posterior mediastinum

Answer 10

Azygous vein, vagus nerve, hemizygous vein, oesophagus Thoracic duct (4 geese and a duck)

Question 11

Define the mediastinum

Answer 11

A cavity within the thorax bordered by the pleura sacs. The mediastinum is divided into superior and inferior areas by the sternal angle (T4/T5)

Question 12

Pharyngeal arch vessels: 3^rd, 4^th and 6^th

Answer 12

3^rd - Common carotid

4^th - Part of the arch of the aorta

6^th - The ductus arteriosus

Question 13

Outline the clinical significance of the transverse sinus

Answer 13

Located posterior to the aorta and the pulmonary vein - can be clamped during surgery