Anatomy Exam 2: Cardiovascular System

Question 1

Describe the structure of the pericardial layers.

Answer 1

The outermost pericardial layer is the “fibrous pericardium”. It is dense connective tissue. It is relatively inelastic, and prevents the heart from overfilling.

The inner layer of pericardium has a parietal layer, continuous with the visceral layer (aka epicardium).

Between the parietal and visceral layers is a thin film of serous fluid = decreased friction.

Question 2

Describe the structure of the pericardial cavity.

Answer 2

Contains thin film of serous fluid, which allows the visceral and parietal pleura to move against each other without friction.

Question 3

In which of the mediastinal subdivisions is the pericardium located?

Answer 3

Middle subdivision of the inferior mediastinum.

Question 4

What are the subdivisions of the mediastinum, what are the landmarks that distinguish them?

Answer 4

The mediastinum is divided into superior and inferior portions.

The superior mediastinum extends up to the manubrium and down to the bottom of T4.

The inferior mediastinum is the space below T4 to the diaphragm. It is subdivided into the anterior, middle, and posterior mediastinum.

Question 5

Compare/contrast the anterior, middle, and posterior mediastinum.

Answer 5

Anterior: sternum to pericardium.

Middle: pericardium and heart.

Posterior: pericardium to vertebral column.

Question 6

Describe arterial blood supply to the pericardium.

Answer 6

The coronary arteries provide arterial supply to the visceral layer only.

The following arteries provide arterial supply to both layers:

• pericardiacophrenic artery
• musculophrenic artery
• bronchial artery (via thoracic aorta)
• esophageal artery (via thoracic aorta)
• superior phrenic artery (via thoracic aorta).

Question 7

Describe venous drainage from the pericardium.

Answer 7

The pericardium is drained by the pericardiacophrenic vein, the internal thoracic vein, and in the posterior, by the azygos system.

Question 8

Describe innervation of the pericardium.

Answer 8

Somatic sensory (fibrous and parietal pleura): phrenic nerves (C3-5)

Visceral sensory (visceral pleura): cardiac plexuses; non-pain only.

Question 9

During an MI, how is pain signaled?

Answer 9

Ischemia in the myocardium travels via cardiac plexuses to the dorsal horn of T4 and T5.

Question 10

What sulci can be seen on the external surface of the heart from an anterior view?

Answer 10

The anterior interventricular groove separates the right and left ventricles.

The atrioventricular groove (aka coronary groove) can be seen between the right atrium and right ventricle.

Question 11

What vessels run in the sulci that are present on the anterior of the heart?

Answer 11

The right coronary artery runs in the coronary groove, between the right atrium and right ventricle. An anterior cardiac vein also runs in this space.

The LAD/anterior interventricular artery lays in the anterior interventricular groove, along with the great cardiac vein.

Question 12

What sulci are present on the posterior of the heart, and what vessels run in them?

Answer 12

The posterior interventricular sulcus runs vertically on the posterior of the heart. The posterior interventricular artery lies in this sulcus, as well as the middle cardiac vein.

Question 13

What are the branches of the RCA and what do they supply?

Answer 13

The right coronary artery has four branches:

1. ) Posterior interventricular (this is the case in right dominance - about 65% of the population).
2. ) Right marginal artery.
3. ) The AV nodal branch.
4. ) The SA nodal branch.
5. )

Question 14

What does the posterior interventricular artery supply?

Answer 14

Supplies AV node, R and L ventricles, and the posterior 1/3 of the interventricular septum.

Question 15

What does the right marginal artery supply?

Answer 15

The right ventricle.

Question 16

What does the RCA supply?

Answer 16

Right atrium, SA/AV nodes, right ventricle.

*if the posterior interventricular artery is a branch, it also supplies the left ventricle and the posterior 1/3 of the interventricular septum.

Question 17

Describe the structure of the valve that separates the right atrium from the right ventricle.

Answer 17

The right atrioventricular valve is a TRICUSPID valve. It has an anterior, posterior, and septal cusp.

Each cusp has associated papillary muscles. When these muscles contract, they pull on chordae tendinae which help keep the valve closed, thus preventing regurgitation.

Question 18

Describe the differences between the right and left ventricles.

Answer 18

The left ventricle has thicker walls than the right.

The left ventricle has finer, more numerous trabeculae carneae than the right.

Both have a smooth surface leading to the opening of their respective semi-lunar valves. In the right ventricle, this is the conus arteriosus. In the left ventricle, this is the aortic vestibule.

Question 19

During diastole, which valves are closed?

Answer 19

Semilunar (pulmonary and aortic valves).

Question 20

During systole, which valves are closed?

Answer 20

AV valves (tricuspid and mitral/bicuspid).

Question 21

Describe the structure of the last valve of the heart that deoxygenated blood passes through on its way to the lungs.

Answer 21

The pulmonary valve is a semilunar valve. It has three cusps but no chordae tendinae or papillary muscles. The cusps are confusingly named: Left (at 12’oclock), Anterior (at 4’oclock), and Right (at 8’oclock).

Question 22

Describe the structure of the first valve that blood passes through as it returns from the lungs to the heart.

Answer 22

The blood will pass through the left atrioventrical valve as it leaves the left atrium and passes into the ventricle. This is called the mitral valve or bicuspid valve. It has two cusps, each with associated papillary muscles which pull on chordae tendinae when contracted. This helps prevent regurgitation back into the atrium.

Question 23

Describe the valve through which blood will pass as it leaves the left ventricle.

Answer 23

Blood will pass through the aortic valve into the aorta. The aortic valve is a semilunar valve with three cusps but no chordae tendinae or papillary muscles. The cusps are confusingly named: Left (at 1 o’clock), Right (at 6 o’clock), and Posterior (at 10 o’clock).

Question 24

How is the interartrial septa formed?

Answer 24

As a fetus, the foramen ovale provides a connection between one atria to the other (bypassing the lungs). During development, it closes and leaves a remnant called the fossa ovalis.

Question 25

Describe the walls of the right atrium.

Answer 25

The posterior of the right atrium is smooth-walled and is called the sinus veranum. It is derived from different embryonic tissue (vascular tissue) than the pectinate muscles (derived from embryonic atrial tissue) that cover the rest of the wall of the right atrium.

The crista terminalis separates the two tissues.

Question 26

Describe the walls of the left atrium.

Answer 26

The interior walls of the left atrium are primarily sinus veranum. The left atrium has less pectinate muscle than the right atrium, which makes sense because it needs to do less pumping than the right (gravity works in its favor).

Question 27

What can happen if the foramen ovale does not close properly?

Answer 27

A patent foramen ovale (a type of atrial septal defect) allows oxygenated blood to be shunted into the right atrium. This can overload the pulmonary system.

The side of the heart and pulmonary trunk can become enlarged when this happens.

Parasternal heave and heart murmur may be evident.