L-11 Internal Structure Of The Heart

Question 1

How is the heart internally divided

Answer 1

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

Question 2

What do heart valves do

Answer 2

Permit the passage of blood in one Direction and prevent its backflow

Question 3

Describe the right atrium

Position, thickness, parts

Answer 3

▪️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

Question 4

Describe the interatrial septum

Answer 4

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

Question 5

What are the veins opening into the right atrium

Answer 5

Superior and inferior vena cava

Coronary sinus

Question 6

What are the structures opening into the right atrium

Answer 6

Superior and inferior vena cava
Coronary sinus
Tricuspid valve

Question 7

Describe the left atrium

Position, thickness, parts

Answer 7

▪️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

Question 8

What are the structures opening into the left atrium

Answer 8

4 pulmonary veins

Bicuspid valve

Question 9

Describe the right ventricle

(Cavity and thickness)

Answer 9

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)

Question 10

How is the tricuspid valve attached

Answer 10

To the popular in muscles of the ventricular wall by the cordae tendinae

Question 11

What are the orifices of the right ventricle

Answer 11

Pulmonary valve

tricuspid valve

Question 12

Describe the left ventricle

Cavity and thickness

Answer 12

Cavity: rounded in cross-section
Thickness: 8-15 mm
Divided into 2 parts inflowing rough part trabeculae carnae and outflowing smooth part aortic vestibule

Question 13

What are the orifices of the left ventricle

Answer 13

Aortic valve

Mitral valve

Question 14

What is the interventricular septum and describe it

Answer 14

▪️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

Question 15

What are the two types of valves

Answer 15

1) atrioventricular valves:tricuspid and bicuspid

2) semi lunar valves: pulmonary valves and aortic valve

Question 16

Describe the tricuspid valve

Answer 16

▪️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

Question 17

Describe the Mitral valve

Answer 17

▪️Transmits blood from left atrium to left ventricle

▪️Has a fibrous ring and 2 cusps forming the valve(ant and post)

Question 18

Describe the pulmonary valve

Answer 18

Formed of a fibrous ring guarded by the pulmonary valve that has three semi lunar cusps (one posterior and two anterior)

Question 19

Describe the aortic valve

Answer 19

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

Question 20

How do the dilations in the sinus of valsalva help

Answer 20

▪️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

Question 21

Describe the fibrous skeleton of the heart and what is its function

Answer 21

▪️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

Question 22

What does electrical insulation provided by the fiberous skeleton do

Answer 22

Forms a barrier between the atria and the ventricles and ensures that electrical conductivity normally only occurs through the bundle of His