W01L06 The Heart: Internal Structure Flashcards
Right atrium: Inflow from 3 vessels bringing deoxygenated blood
Inferior vena cava
Superior vena cava
Coronary sinus
Right atrium: Outflow tract tricuspid valve
Faces anteriorly and medially
Opens into the right ventricle
Right atrium: Anterior wall trabeculated
Musculi pectinati, starts at the crista terminalis which is a ridge
Right atrium: Posterior wall smooth - interatrial septum
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
Right atrium summary (MD2001)
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
Right ventricle: circulation path
De-ox blood in through tricuspid valves from right atrium and out through infundibulum and pulmonary trunk
Infundibulum
Smooth walled funnel of the right ventricle
Allows smooth laminar flow
Right ventricle key features
Forms most of the sternocostal surface and some of the diaphragmatic surface
Crescentic in cross section because the interventricular septum bulges from the left
Right ventricle: Trabeculated Walls and papillary muscles
Trabeculae carneae (course) 3 papillary muscles with chordae tendineae - septal, posterior, anterior
Right ventricle: Septomarginal trabeculum
Moderator band
Bridge between the lower portion of the interventricular septum and the anterior papillary muscle for cardiac conduction
Tricuspid valve and how it stays open
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)
3 cusps of the tricuspid valve
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
Active competence
Valve competence requires functional papillary muscles
Each papillary muscle sends chordae tendineae to 2 cusps
Right ventricle: pulmonary valve
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
Ventricles in summary MD2001
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
Trabeculae Carneae
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
Papillary muscles
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
Pulmonary trunk relations
Lies inf. to arch of aorta
Linked to aorta via ligamentum arteriosum
Divides to become left and right pulmonary arteries
Ligamentum arteriosum
Derived from ductus arteriosus in fetus
Left atrium summary
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
Left ventricle summary
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
Mitral/Bicuspid valve
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)
Importance of knowing active competence
MI can damage papillary muscles and valve competence cannot be maintained, resulting in leakage
Aortic valve
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
Cardiac skeleton
Fibrous skeleton, supports valves and myocardium
Electrically separates atria and ventricles
Bundle of His should be the only conduction between them (arrhythmias)
LA, LV, and Ao during systole
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)
LA, LV, and Ao during diastole
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
Importance of knowing active competence
MI can damage papillary muscles and valve competence cannot be maintained, resulting in leakage
Aortic valve
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
Cardiac skeleton
Fibrous skeleton, supports valves and myocardium
Electrically separates atria and ventricles
Bundle of His should be the only conduction between them (arrhythmias)
LA, LV, and Ao during systole
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)
LA, LV, and Ao during diastole
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
Calcification of the aortic valve could cause…
Probably cause an extra heart sound during systole
