Blood Supply of the Heart

Question 1

Describe the arterial and venous supply of the heart

Answer 1

Arterial supply: Coronary arteries and branches
Venous drainage: Coronary sinus and tributaries

Question 2

Number of coronary arteries

Answer 2

1 right and 1 left

Question 3

Where do the coronary arteries arise from?

Answer 3

Ascending aorta

Question 4

Which part of the heart does not receive oxygenated blood from the coronary arteries?

Answer 4

Inner 75-100µm of the endothelial layer of the heart receives nutrition from the blood in the heart chambers

Question 5

Are the coronary arteries end arteries?

Answer 5

Anatomically not end arteries but functionally end arteries

Question 6

Describe the course of the right coronary artery

Answer 6

Passes forwards and to the right emerging on the surface of the heart between the root of the pulmonary trunk and right auricle
Runs downwards in the right anterior coronary sulcus to the junction of the right and inferior borders of the heart
Winds round the inferior border to reach the diaphragmatic surface of the heart
Runs backwards and to the left in the right posterior coronary sulcus to reach the posterior interventricular groove
Terminates by anastomosing with the circumflex branch of left coronary artery at the crux

Question 7

What are the branches of the right coronary artery?

Answer 7

Anterior, posterior and lateral atrial branches. The SA nodal artery arises from the atrial branch and supplies the SA node
Right conus artery forms an arterial circle around pulmonary trunk with a similar branch from the left coronary artery. The circle is called, ‘Annulus of Vieussens’
Anterior and posterior ventricular branches. The anterior group lies on the sternocostal surface while posterior group traverses the diaphragmatic surface of the heart.
Right marginal artery arises as the right coronary artery crosses the right border of heart. It runs along its inferior border till the apex of heart
Posterior interventricular branch arises close to the crux of heart and lies in the posterior interventicular groove. It gives septal branches to posterior one-third of interventricular septum. It also supplies AV node

Question 8

Areas of distribution of the right coronary artery

Answer 8

Right atrium
Greater part of right ventricle except anterior Interventricular groove
Small part of left ventricle adjoining the posterior interventricular groove
Posterior 1/3rd of interventricular septum
Entire conducting system except left branch of the AV bundle

Question 9

Describe the course of the left coronary artery

Answer 9

Runs forwards and to the left and emerges between the pulmonary trunk and the left auricle
Gives the anterior interventricular branch which runs downwards in the anterior interventricular groove
The further continuation of the left coronary artery is called the circumflex artery
After giving off the anterior interventricular branch, the artery runs to the left in the left anterior coronary sulcus
It winds round the left border of the heart and continues in the left posterior coronary sulcus
Near the posterior interventricular groove, it terminates by anastomosing with the right coronary artery

Question 10

What are the branches of the left coronary artery?

Answer 10

Anterior interventricular branch
Circumflex branch: Terminal part of left coronary artery

Question 11

What are the branches of the anterior interventricular branch?

Answer 11

i. Anterior ventricular branches for the ventricles. The large branch is called ‘left diagonal artery’
ii. Septal branches which supply anterior two-thirds of the interventricular septum
iii. Left conus artery forms an arterial ring around the pulmonary trunk

Question 12

What are the branches of the circumflex artery?

Answer 12

i. Left marginal artery which lies along the left border of heart till the apex of heart
ii. Anterior and posterior ventricular branches
iii. Anterior, posterior and lateral atrial branches

Question 13

Areas of distribution of the left coronary artery

Answer 13

Left atrium
Greater part left ventricle except posterior Interventricular groove
Small part right ventricle at anterior Interventricular groove
Anterior 2/3rd of interventricular septum
Left branch of AV bundle

Question 14

What is cardiac dominance?

Answer 14

Describes which coronary artery gives rise to the posterior interventricular branch

Question 15

Right cardiac dominance

Answer 15

Right coronary artery gives rise to the posterior interventricular branch
Majority of population have right cardiac dominance

Question 16

Left cardiac dominance

Answer 16

Left coronary artery gives rise to the posterior interventricular branch
Approximately 10%

Question 17

What conditions commonly affect people with left cardiac dominance?

Answer 17

Coronary diseases

Question 18

Codominance

Answer 18

Posterior interventricular artery arises from both coronary arteries

Least affected by coronary diseases

Question 19

What are the cardiac anastomoses?

Answer 19

First two coronary arteries anastomose in the myocardium

Question 20

What are the extracardiac anastomoses?

Answer 20

Coronary arteries anastomose with other arteries, including:
* Vasa vasorum of the aorta
* Vasa vasorum of the pulmonary arteries
* The internal thoracic arteries
* The bronchial arteries
* The pericardiacophrenic arteries

Last three anastomose through the pericardium
These channels open up in emergencies when both coronary arteries are obstructed

Question 21

Describe the venous drainage of the heart

Answer 21

Venous blood drains from the heart into the right atrium through:
* The coronary sinus
* Anterior cardiac veins
* Venae cordis minimae (thebesian veins)

Question 22

Characteristics of the coronary sinus

Answer 22

2 to 3cm long
Situated - Left posterior coronary sulcus
Opens - Right atrium
Valve - Thebesian valve

Question 23

What are the tributaries of the coronary sinus?

Answer 23

1. Great cardiac vein
2. Small cardiac vein
3. Middle cardiac vein
4. Posterior vein of left ventricle
5. Oblique vein of left atrium (vein of Marshall)

Question 24

Characteristics of the anterior cardiac vein

Answer 24

Drains anterior part of right ventricle
Usually 2 or 3 in number - parallel to each other
Opens into right atrium

Question 25

Characteristics of venae cordis minimae/Thebesian veins

Answer 25

Opens into all chambers
Numerous in right atrium & ventricle