W01L06 The Heart: Internal Structure

Question 1

Right atrium: Inflow from 3 vessels bringing deoxygenated blood

Answer 1

Inferior vena cava
Superior vena cava
Coronary sinus

Question 2

Right atrium: Outflow tract tricuspid valve

Answer 2

Faces anteriorly and medially

Opens into the right ventricle

Question 3

Right atrium: Anterior wall trabeculated

Answer 3

Musculi pectinati, starts at the crista terminalis which is a ridge

Question 4

Right atrium: Posterior wall smooth - interatrial septum

Answer 4

Fossa ovalis and limbus fossa ovalis (ridge) which are remnants of foramen ovale in fetus
SinoAtrial node (pacemaker) close to the opening of the SVC
AtrioVentricular node close to the tricuspid valve

Question 5

Right atrium summary (MD2001)

Answer 5

The muscular ridges (musculi pectinati) pass from the crista terminalis into the auricle, they provide some power of contraction without appreciably thickening the cardiac wall
The fossa ovalis is the site of what was the foramen ovale in embryo
De-ox blood enters from SVC and IVC and coronary sinus
Blood leaves via the tricuspid valve

Question 6

Right ventricle: circulation path

Answer 6

De-ox blood in through tricuspid valves from right atrium and out through infundibulum and pulmonary trunk

Question 7

Infundibulum

Answer 7

Smooth walled funnel of the right ventricle

Allows smooth laminar flow

Question 8

Right ventricle key features

Answer 8

Forms most of the sternocostal surface and some of the diaphragmatic surface
Crescentic in cross section because the interventricular septum bulges from the left

Question 9

Right ventricle: Trabeculated Walls and papillary muscles

Answer 9

Trabeculae carneae (course)
3 papillary muscles with chordae tendineae - septal, posterior, anterior

Question 10

Right ventricle: Septomarginal trabeculum

Answer 10

Moderator band

Bridge between the lower portion of the interventricular septum and the anterior papillary muscle for cardiac conduction

Question 11

Tricuspid valve and how it stays open

Answer 11

The valve opens and closes due to blood pressure differences
The papillary muscles and chordae tendineae prevent cusp eversion during systole (they do not close the valves but maintain closure)

Question 12

3 cusps of the tricuspid valve

Answer 12

Anterior, posterior, septal
Attached to a fibrous ring which is part of the fibrous skeleton of the heart
Closes during ventricular contraction (systole) prevents back flow to the atrium

Question 13

Active competence

Answer 13

Valve competence requires functional papillary muscles

Each papillary muscle sends chordae tendineae to 2 cusps

Question 14

Right ventricle: pulmonary valve

Answer 14

3 cusps (right, left, anterior) in root of pulmonary trunk
Opens during systole and closes in diastole due to blood pressure differences
Do not have papillary muscles or chordae tendineae - passive competence

Question 15

Ventricles in summary MD2001

Answer 15

The muscular ridges in the ventricles that give power of contraction without taking up space are the trabeculae carneae
The tricuspid and mitral valves are opened and closed by the pressure of blood
The walls of each ventricle becomes smooth near its outflow to create laminar blood flow into the pulmonary trunk and aorta

Question 16

Trabeculae Carneae

Answer 16

The muscular ridges in the ventricles that give power of contraction without taking up space (don’t increase thickness of the walls)
Give rise to papillary muscles each of which sends chordae tendineae to the edges of two valve cusps

Question 17

Papillary muscles

Answer 17

The papillary muscles and chordae tendineae prevent cusp eversion into the atrium during ventricular contraction
Myocadial infarction my affect papillary muscles and cause valve incompetence

Question 18

Pulmonary trunk relations

Answer 18

Lies inf. to arch of aorta
Linked to aorta via ligamentum arteriosum
Divides to become left and right pulmonary arteries

Question 19

Ligamentum arteriosum

Answer 19

Derived from ductus arteriosus in fetus

Question 20

Left atrium summary

Answer 20

LA forms the base of the heart
Inflow oxygenated blood from the pulmonary veins
Outflow mitral (bicuspid) valve
Interatrial wall smooth
Fewer pectinate muscles
Posterior to the LA are the oesophagus and descending thoracic aorta

Question 21

Left ventricle summary

Answer 21

Inflow tract anterior through mitral valve to apex
Outflow tract upwards and backwards, posterior to the pulmonary valve through the aortic valve
Trabeculated walls with numerous trabeculae carneae
2 papillary muscles with chordae tendineae
Circular in corss section because the interventricular wall bulges towards the right
Thick walled consisting of membranous and muscular portions from 4 embryological origins

Question 22

Mitral/Bicuspid valve

Answer 22

2 cusps (anterior, posterior)
Attached to 2 papillary muscles by the chordae tendineae
Attached to a fibrous ring which is part of the fibrous skeleton of the heart
Closes during ventricular contraction (systole)

Question 23

Importance of knowing active competence

Answer 23

MI can damage papillary muscles and valve competence cannot be maintained, resulting in leakage

Question 24

Aortic valve

Answer 24

3 cusps at the apex of the aortic vestibule (right, left and posterior, also described as coronary and noncoronary)
As blood recoils after ventricular contraction and fills the aortic sinses, it is automatically forced into the coronary arteries
Passive competence

Question 25

Cardiac skeleton

Answer 25

Fibrous skeleton, supports valves and myocardium
Electrically separates atria and ventricles
Bundle of His should be the only conduction between them (arrhythmias)

Question 26

LA, LV, and Ao during systole

Answer 26

Atria relax and fill with blood
Ventricles contracts forcing blood upwards and backwards
Closing the first mitral valve (and tricuspid) - 1st heart sound at start of systole
Forcing blood through the aortic valve (and pulmonary)

Question 27

LA, LV, and Ao during diastole

Answer 27

Atrium contracts and forces blood through the mitral valve (and tricuspid)
Ventricles relax and fills with blood
Aortic valve (and pulmonary) closed by pressure of blood trying to come back under elastic recoil - 2nd heart heart sound at end of systole
Aortic sinuses fill and blood enters coronary arteries

Question 28

Importance of knowing active competence

Answer 28

MI can damage papillary muscles and valve competence cannot be maintained, resulting in leakage

Question 29

Aortic valve

Answer 29

3 cusps at the apex of the aortic vestibule (right, left and posterior, also described as coronary and noncoronary)
As blood recoils after ventricular contraction and fills the aortic sinses, it is automatically forced into the coronary arteries
Passive competence

Question 30

Cardiac skeleton

Answer 30

Fibrous skeleton, supports valves and myocardium
Electrically separates atria and ventricles
Bundle of His should be the only conduction between them (arrhythmias)

Question 31

LA, LV, and Ao during systole

Answer 31

Atria relax and fill with blood
Ventricles contracts forcing blood upwards and backwards
Closing the first mitral valve (and tricuspid) - 1st heart sound at start of systole
Forcing blood through the aortic valve (and pulmonary)

Question 32

LA, LV, and Ao during diastole

Answer 32

Atrium contracts and forces blood through the mitral valve (and tricuspid)
Ventricles relax and fills with blood
Aortic valve (and pulmonary) closed by pressure of blood trying to come back under elastic recoil - 2nd heart heart sound at end of systole
Aortic sinuses fill and blood enters coronary arteries

Question 33

Calcification of the aortic valve could cause…

Answer 33

Probably cause an extra heart sound during systole