The Cardiovascular System

Question 1

Where is the mediastinum?

Answer 1

Between the pleura. Extends from the sternum to the vertebral column.
Contains all of the thoracic structures, except the lungs and pleura.

Question 2

What are the borders of the heart anatomically related to?

Answer 2

Anterior - sternum and costal cartilages 4-7.
Posterior - oesophagus and descending aorta.
Lateral - pleura and phrenic nerve.
Inferior - central tendon of the diaphragm.

Question 3

What sections of the heart correspond to the borders?

Answer 3

Superior - auricles and great vessels.
Right - RA.
Left - LV.

Anterior (sternocostal) - 1/3RA, 2/3RV, LV.
Posterior (basal) - LA.
Inferior (diaphragmatic) - RV + LV.

Question 4

Where is the heart and apex located?

Answer 4

Heart - lies anterior to T5-T8.
Apex - 5th left intercostal space, midclavicular line (LV).

Question 5

What is the pericardium?

Answer 5

Fibrous - dense CT sac.
Serous - outer parietal layer and inner visceral layer (epicardium).
Pericardial cavity - between the parietal and visceral layers, filled with fluid.

Question 6

What are the major sulci?

Answer 6

Coronary (atrioventricular) sulcus - between the atria and ventricles.
Interventricular sulcus - between the right and left ventricles.
The two major sulci contains the branches of the coronary arteries.

Question 7

What are the coronary arteries?

Answer 7

RCA - branches into the right marginal and posterior interventricular artery.
LCA - branches into the left anterior descending and circumflex artery.

Question 8

Where are the anastomoses of the heart?

Answer 8

Anterior and posterior descending (interventricular) arteries.
Circumflex and RCA.
Occurs on the posterior surface of the heart.

Question 9

What are the cardiac veins?

Answer 9

Great cardiac vein - lies alongside the anterior descending artery.
Middle cardiac vein - lies alongside the posterior descending artery.
Small cardiac vein - lies alongside the right marginal artery.

Question 10

Where do the cardiac veins drain?

Answer 10

These three veins drain into the coronary sinus lying alongside the circumflex artery. The coronary sinus and anterior cardiac veins drain into the RA.

Question 11

What are the nerves that innervate the heart?

Answer 11

Phrenic - innervates the fibrous pericardium and the parietal layer of serous pericardium (pain).
Vagus - innervates the myocardium and the visceral layer of serous pericardium (para).
T1-T4 - same as vagus, but sympathetic. Refers pain to the inner surface of the upper arm.

Question 12

What do the different arteries of the heart supply?

Answer 12

RCA - RA and RV.
Left circumflex - LA and LV.
Left anterior descending - RV, LV, and interventricular septum.
Left marginal - LV.
Right marginal - RV and the apex.

Question 13

What is the intrinsic innervation of the heart?

Answer 13

SAN signals stimulate atrial contraction, which travels to the AVN. After a delay, the stimulus is conducted through the Bundle of His, to the left and right bundle branches, then to the endocardium (at the apex of the heart), and to the ventricles and ventricular epicardium.

Question 14

What are the locations of the heart valves and heart sounds?

Answer 14

Above to downwards - P, A, M, T.
P - upper left sternal border at the level of the 2nd left intercostal space.
A - upper right sternal border at the level of the 2nd left intercostal space.
M - over the apex beat point.
T - lower left sternal border at the level of the 4th left intercostal space.

Question 15

Where are the locations of the heart sounds?

Answer 15

The heart sounds radiate roughly to the corners of the heart, where they can be auscultated.

Question 16

What features does the RA have?

Answer 16

Openings for the IVC, SVC, and coronary sinus.
Musculi pectinate.
Fossa ovalis (in the interatrial septum).

Question 17

What features does the RV have?

Answer 17

Tricuspid - 3 valve cusps, chordae tendineae, 3 papillary muscles.
Moderator band - septomarginal trabeculum.
Trabeculae carneae - contractile fleshy struts.

Question 18

What is the function of the trabeculae carneae?

Answer 18

Prevents suction that would occur with a flat surface and impair the heart’s ability to pump efficiently.

Question 19

What features does the LA have?

Answer 19

A smooth and small chamber, lying posterosuperior against the oesophagus.
Forms the basal surface of the heart.

Has an interventricular septum - between the ventricles, 3x thicker in the LV.
Has openings for the pulmonary veins.

Question 20

What features does the LV have?

Answer 20

Mitral - 2 valve cusps, chordae tendineae, 2 papillary muscles.
Forms the apex of the heart.
Trabeculae carneae.