L-11 Internal Structure Of The Heart Flashcards
How is the heart internally divided
Right and left by longitudinal septum
Each half is divided by a transverse septum containing an atrioventricular valve in to:
Posterior(1/3) towards the base: atrium
Anterior (2/3) towards the apex: ventricle
What do heart valves do
Permit the passage of blood in one Direction and prevent its backflow
Describe the right atrium
Position, thickness, parts
▪️Position:it forms the right border and right surface of the heart
▪️Thickness: 2mm
▪️Parts: anterior rough part made of pectinate muscles in auricle
Posterior smooth part
▪️Two parts are separated by Crista terminalis
▪️Faint groove on the outer surface sulcus terminalis
Describe the interatrial septum
Shows oval depression called fossa ovalis which represents the site of the foreman ovale
Bounded above and on the side by a raised margin called limbus fossa ovalis
What are the veins opening into the right atrium
Superior and inferior vena cava
Coronary sinus
What are the structures opening into the right atrium
Superior and inferior vena cava
Coronary sinus
Tricuspid valve
Describe the left atrium
Position, thickness, parts
▪️Position:lies behind and to the left of the right atrium forming the greater part of the base of the heart
▪️thickness:3 mm
▪️Parts:anterior part(pectinate muscles) including only left auricle and smooth posterior part formed by entrance of the four pulmonary veins
What are the structures opening into the left atrium
4 pulmonary veins
Bicuspid valve
Describe the right ventricle
(Cavity and thickness)
Cavity:it is semilunar in cross-section
Thickness:4-5mm
Divided into two parts inflowing rough part (trabculae carnae)and out flowing smooth part(conus arteriosus)
How is the tricuspid valve attached
To the popular in muscles of the ventricular wall by the cordae tendinae
What are the orifices of the right ventricle
Pulmonary valve
tricuspid valve
Describe the left ventricle
Cavity and thickness
Cavity: rounded in cross-section
Thickness: 8-15 mm
Divided into 2 parts inflowing rough part trabeculae carnae and outflowing smooth part aortic vestibule
What are the orifices of the left ventricle
Aortic valve
Mitral valve
What is the interventricular septum and describe it
▪️Septum separating the two ventricles
▪️Oblique in position being biconcave towards the left ventricle and convex towards the right ventricle
▪️ it has two parts
membranous part:the small upper area muscular part:the lower large thick part
What are the two types of valves
1) atrioventricular valves:tricuspid and bicuspid
2) semi lunar valves: pulmonary valves and aortic valve
Describe the tricuspid valve
▪️Transmits blood from right atrium to right ventricle
▪️Fibrous ring and 3 cusps forming the valve(ant, post, and septal)
▪️Each cusp is attached to the cordae tendinae of the 3 papillary muscles of the right ventricle
Describe the Mitral valve
▪️Transmits blood from left atrium to left ventricle
▪️Has a fibrous ring and 2 cusps forming the valve(ant and post)
Describe the pulmonary valve
Formed of a fibrous ring guarded by the pulmonary valve that has three semi lunar cusps (one posterior and two anterior)
Describe the aortic valve
Structure is similar to the pulmonary valve but its 3 semilunar cusps(1ant and 2 post)
Dilatation(sinus of valsalva) in the aortic wall just above each cusp
How do the dilations in the sinus of valsalva help
▪️Allow blood to flow behind the cusps at the very beginning of the ventricular relaxation in the diastole and ensure that aortic valve shuts and that the cusps are not flattened against the side of the aorta
▪️allow blood to freely enter the right and left coronary arteries
Describe the fibrous skeleton of the heart and what is its function
▪️Framework of dense collagen around the atrioventricular junction and the arterial outflow
▪️provides structural support for the heart particularly by the stabilizing the heart valves and it also prevents the heart from being overstretched
What does electrical insulation provided by the fiberous skeleton do
Forms a barrier between the atria and the ventricles and ensures that electrical conductivity normally only occurs through the bundle of His
