The Heart!

Question 1

In which specific region of the thorax is the heart and its pericardial sac located?

Answer 1

The middle mediastinum

Question 2

The apex of the heart projects in which direction?

Answer 2

Inferiorly and to the left

Question 3

What is the ligamentum arteriosum and what was its fetal function?

Answer 3

The obliterated ductus arteriosum. Fetally, it was used as a bypass for fetal blood that passed into the right ventricle by not passing through the foramen ovale and is shunted out into the aorta rather than continuing out into the lungs as oxygenation is neither needed or possible.

Question 4

What is the moderator band? Where is it found? What is its function?

Answer 4

A band of cardiac muscle that stretches from the septal wall of the right ventricle to the base of the anterior papillary muscle. It contains Purkinje fibers so is thought to represent a shortcut for the conducting system of the heart.

Question 5

Name the parts of the septum found between the right and left heart.

Answer 5

From the base up: the muscular interventricular septum, the membranous interventricular septum, the membranous atrioventricular septum and the membranous interatrial septum.

Question 6

What was the fossa ovalis in the fetus? What was it’s function?

Answer 6

The foramen ovale. A fetal bypass for oxygenated blood, bypassing the right ventricle and lungs.

Question 7

Know the arrangement of the various components of the AV and semilunar valves.

Answer 7

An AV valve consists of the cusp, the fibrous chordae tendineae and a papillary muscle. A semilunar valve consists of a fibrous cusp, a thin flexible edge on the cusp - the lunule and a geometric central portion of the lunule - the nodule.

Question 8

Be able to name each cusp of the semilunar and A-V valves.

Answer 8

Pulmonary semilunar: anterior, left and right; aortic semilunar: left, right and posterior; mitral valve: anterior and posterior; tricuspid valve; anterior, posterior and septal.

Question 9

What is the function of the papillary mm.?

Answer 9

They contract to pull down on the chordae tendineae which in turn prevent the cusps of the AV valves from everting into the atria during contraction of the ventricle.

Question 10

Be able to identify the correct location for listening to the specific valve sounds for each
valve of the heart.

Answer 10

Diagram on pg 180?

Question 11

What is the fibrous skeleton of the heart?

Answer 11

A fibrous thickening (network) within the cardiac muscle surrounding the various valvular openings of the heart.

Question 12

What is the function of the fibrous skeleton?

Answer 12

Provides for the sturdy attachment of the cusps of both the AV and semilunar valves of the heart.

Question 13

How does the morphology of the fibrous skeleton differ around AV as opposed to
semilunar valves?

Answer 13

Around the AV openings the skeleton is ring-like. Around the semilunar openings the skeleton is cuff-like to allow attachment of the pocket-like cusps.

Question 14

Which spinal cord levels contain sympathetic neurons associated with innervating the cardiopulmonary plexus?

Answer 14

T1 to T5

Question 15

How do these fibers access the plexus?

Answer 15

Via the cardiac cervical rami.

Question 16

Where do the parasympathetic fibers that penetrate this plexus come from?

Answer 16

The vagus nerve (CN X).

Question 17

What is the function of each ANS fiber type in the heart?

Answer 17

Parasympathetic fibers slow heart rate, sympathetic fibers speed heart rate.

Question 18

What is the function of each ANS fiber type in the lungs?

Answer 18

Parasympathetic fibers constrict smooth muscle, sympathetic fibers relax smooth muscle.

Question 19

State the location of the SA and AV nodes of the conduction system of the heart.

Answer 19

The SA nodes is found subepicardially between the base of the superior vena cava and the top of the sulcus terminalis on the right atrium. The AV node is found subendocardially between the opening of the coronary sinus and the tricuspid valve on the inside of the right atrium.

Question 20

Be able to trace the pathway of impulse conduction in the heart.

Answer 20

From the cardiac plexus - SA node - internodal fibers traverse the atrial wall - AV node - AV bundle to the top of the muscular interventricular septum - bundles of HIS spread impulse throughout entire left and right ventricular walls.

Question 21

What cells comprise the bundles of His? They are modified ______ cells

Answer 21

Purkinje fibers.

Cardiac muscle fibers (cells).

Question 22

Between which two anatomical components of the right ventricle does the moderator
(septomarginal) band extend?

Answer 22

The muscular interventricular septum to the base of the anterior papillary muscle of the right ventricle.

Question 23

Be able to label the components of the coronary circulation on a diagram of the
heart - anterior and posterior surfaces (in conjunction with the surface anatomy features).

Answer 23

This is critical. Will be on the exam as well as the lab exam. See the diagrams on page 176. Be able to superimpose the surface anatomy of the heart onto these diagrams well as label the vessels of the aortic arch from the anterior view as well as the posterior view.

Question 24

What is meant by the indirect nature of the venous drainage of the heart?

Answer 24

Venous blood from the heart does not drain directly back to the right atrium but first drains to the coronary sinus which in turn drains to the right atrium - indirect venous drainage.

Question 25

Name an exception to this indirect venous drainage - and the locations drained.

Answer 25

The anterior cardiac veins. They drain blood from the right ventricle directly back into the right atrium. In addition tiny veins (venae cordis minimae) drain tiny amounts of venous blood directly back into all 4 chambers.

Question 26

List the 3 arterial coronary anastomoses?

Answer 26

1. Betweeen the continuation of the RCA and circumflex aa.;
2. Between the anterior interventricular and posterior interventricular aa.; and
3. Between anterior and posterior interventricluar aa. within the muscular interventricular septum of the heart.

Question 27

Where are these major arterial anastomoses of the heart located?

Answer 27

On the posterior surface (except for the interventricular septal ones).

Question 28

What is the function of these anastomoses?

Answer 28

They allow small amounts of blood to pass between the RCA and LCA. However, they are generally referred to as insufficient anastomoses as insufficent amounts of blood pass between these vessels to prevent significant heart (myocardium) damage.

Question 29

Which vessels primarily supply the muscular interventricular septum?

Answer 29

Anterior and posterior interventricular arteries - the larger branches come from the anterior interventricular artery.

Question 30

Typically, which coronary a. is most dominant?

Answer 30

The left coronary artery is typically dominant.

Question 31

the right coronary artery comes off which cusp?

Answer 31

the right cusp of off the aorta semilunar valve