The Heart and Pericardium

Question 1

What are the border and contents of the middle mediastinum?

Answer 1

Anterior- pericardium, heart and pericardium
Posterior- pericardium, tracheal bifurcation (L and R main bronchi)
Lateral- mediastinal pleura, ascending aorta
Superior- sternal angle and T4, pulmonary trunk
Inferior- diaphragm, superior vena cava

Question 2

What is the pericardium?

Answer 2

Fibroserous fluid filled sac
Surrounds heart muscle and great vessels
Lies within middle mediastinum

Question 3

What are the two main layers of the pericardium?

Answer 3

Fibrous

Serous

Question 4

Describe the fibrous layer of the pericardium

Answer 4

Outer layer
Tough connective tissue
Inextensible
Central tendon of diaphragm

Question 5

Describe the serous layer of the pericardium

Answer 5

Inner layer
Single sheet epithelial cells
Parietal layer
Pericardial cavity- fluid filled
Visceral layer (epicardium)

Question 6

What are the functions of the pericardium?

Answer 6

Fixation within mediastinum
Prevents over filling of heart
Lubrication (thin fluid film reduces friction)
Protection from infection

Question 7

How is the pericardium innervated?

Answer 7

Phrenic nerve (C3, 4, 5)
Keeps the diaphragm ‘alive’
Referred pain

Question 8

What are the pericardial sinuses called?

Answer 8

Transverse pericardial sinus

Oblique pericardial sinus

Question 9

Describe the transverse pericardial sinus

Answer 9

Lies between arterial outflow (posteriorly) and venous inflow (anteriorly)
Lies deep/posterior to the ascending aorta and pulmonary trunk and anterior to the superior vena cava/ posterior to great vessels
Coronary artery bypass grafting
Forms due to the looping of the heart tube during foetal development

Question 10

Describe the oblique pericardial sinus

Answer 10

Blind ending passageway

Reflection of pericardium onto pulmonary veins

Question 11

What is the clinical relevance of the pericardium?

Answer 11

Cardiac tamponade (build-up of blood or other fluid in pericardial sac= pressure on heart, cannot pump effectively)- inextensible fibrous layer
Pericarditis- inflammation rom bacterial infection or infarction
Coronary Artery Bypass Grafting- ligation of arteries, transverse pericardial sinus

Question 12

How is the heart positioned in the body?

Answer 12

A pyramid which has fallen over

Anteroinferior and left lateral positioned apex

Question 13

What are the surfaces and borders of the heart?

Answer 13

Anterior (sternocostal)- right ventricle/ Right border- right atrium
Posterior (Base)- Left atrium/ Inferior border- L and R Ventricles
Inferior (Diaphragmatic)- Left and Right ventricles/ Left border- Left Ventricle and part of Left atrium
Right pulmonary- right atrium and Left pulmonary- Left Ventricle/ Superior border- left and right atria, great vessels

Question 14

What are sulci?

Answer 14

Grooves created by internal divisions

Question 15

What are the sulci of the heart?

Answer 15

Coronary sulcus

Anterior and posterior interventricular sulci

Question 16

What are the layers of the heart wall?

Answer 16

Endocardium
Subendocardial layer
Myocardium
 Subepicardial layer
Epicardium (Visceral Pericardium)

Question 17

Describe the endocardium

Answer 17

Innermost layer
Lines cavities and valves
Loose connective tissue and simple squamous epithelium
Regulates contractions
Role in development

Question 18

Describe the subendocardial layer

Answer 18

Joins endocardium and myocardium
Loose layer of connective tissue
Contains neurovasculature of heart conducting system

Question 19

Describe the myocardium

Answer 19

Cardiac muscle (involuntary striated muscle)
Cardiac contractions

Question 20

Describe the Subepicardial layer

Answer 20

Joins myocardium with epicardium

Question 21

Describe the epicardium

Answer 21

Outermost layer of the heart
Visceral layer of pericardium
Connective tissue and fat- secretes lubricating fluid
Lined by simple squamous epithelial cells

Question 22

Describe the right atrium

Answer 22

Receives blood from superior and inferior vena cava, coronary veins
Right auricle (atrial appendage, muscular cone-shaped pouch)
2 distinct parts divided by Crista Terminalis
Coronary sinus (between IVC and right atrioventricular orifice)
Sino-atrial node

Question 23

What is the Crista Terminalis?

Answer 23

Junction between the sinus venosus and the heart in the developing embryo
Smooth muscular ridge in superior portion of RA that divides musculi pectinati and the right atrial appendage from smooth surface of right atrium

Question 24

What is the sinus vernarum?

Answer 24

Posterior to Crista Terminalis
Smooth wall
Derived from embryonic sinus venosus

Question 25

What is the Atrium Proper?

Answer 25

Anterior to Crista Terminalis, includes auricle Rough muscular wall (pectinate muscles- musculi pectinati) Derived from primitive atrium

Question 26

What is the interatrial septum?

Answer 26

Muscular wall separating atria | Oval depression on septal wall of RA Fossa Ovalis

Question 27

Describe the right ventricle

Answer 27

``` Receives blood from RA Pumps blood to pulmonary artery via pulmonary orifice Triangular shape Anterior heart border Inflow and outflow portions Separated by supraventricular crest ```

Question 28

Describe the inflow portion of the right ventricle

Answer 28

Trabeculae carnae 'sponge like' (ridges, bridges, pillars/papillary muscles) Papillary muscle base attached to ventricle Chordae Tendineae Cusps of Tricuspid valve

Question 29

Describe the outflow portion of the right ventricle

Answer 29

``` Conus arteriosus Superior ventricle leading to pulmonary artery Pulmonary semilunar valve Derived from embryonic Bulbus cordis Smooth walls No trabeculae carnae ```

Question 30

Describe the left atrium

Answer 30

Receives blood from pulmonary veins Forms posterior border (base) of heart Left auricular appendage

Question 31

Describe the inflow portion of the left atrium

Answer 31

Receives blood from the pulmonary veins Smooth surface Derived from pulmonary veins Left atrial side of fossa ovalis

Question 32

Describe the outflow portion of the left atrium

Answer 32

Found anteriorly, includes auricle Lined with pectinate muscles Derived from embryonic antrium

Question 33

Describe the left ventricle

Answer 33

Receives blood from left atrium Forms apex of the heart] Left and inferior heart borders Inflow and outflow portions

Question 34

Describe the inflow portion of the left ventricle

Answer 34

``` Trabeculae carnae 2 Papillary muscles Chordae Tendineae attach cusps of mitral valve Bicuspid Interventricular septum ```

Question 35

Describe the outflow portion of the left ventricle

Answer 35

Aortic vestibule (superior region of left ventricle inferior to aortic orifice, outflow tract) Smooth walls Derived from Bulbus Cordis

Question 36

Describe heart valves in general

Answer 36

Ensure blood flow in one direction Connective tissue and lined in endocardium 4- 2 atrioventricular, 2 semilunar

Question 37

Describe the action of Atrioventricular valves

Answer 37

Close at start of systole (first heart sound) | Valves are supported by chordae tendineae

Question 38

Describe the Tricuspid valve

Answer 38

Guards right atrioventricular orifice 3 cusps (anterior, septal, posterior) 3 supporting papillary muscles

Question 39

Describe the mitral valve

Answer 39

Guards left atrioventricular orifice 2 cusps (anterior and posterior) 2 supporting papillary muscles

Question 40

Describe the semilunar valves

Answer 40

Close at the start of diastole (second heart sound) Found between ventricles and corresponding outflow tracts Sinuses Lunule (thickened free edge) Nodule (widest area)

Question 41

Describe the pulmonary valve

Answer 41

``` Guards pulmonary orifice (right ventricle and pulmonary trunk) 3 cusps (right, left and posterior) ```

Question 42

Describe the aortic valve

Answer 42

Guards aortic orifice (left ventricle and ascending aorta) 3 cusps (right, left and posterior) Left and right coronary aortic sinuses

Question 43

What causes the first heart sound?

Answer 43

Tricuspid and mitral valves

Question 44

What causes the second heart sound?

Answer 44

Aortic and pulmonary valve

Question 45

Describe the coronary circulation

Answer 45

Right coronary artery- right marginal artery, posterior interventricular artery (85%) Left coronary artery- left anterior descending artery, left marginal artery, left circumflex artery

Question 46

Describe the right coronary arteries

Answer 46

Right coronary artery= supplies the right atrium and the right ventricle Right marginal artery= supplies the right ventricle and the apex Posterior interventricular artery= supplies the right and the left ventricles, and the interventricular septum anterior interventricular artery

Question 47

Describe the left coronary arteries

Answer 47

Left anterior descending artery- supplies the left and right ventricles and the interventricular septum Left marginal artery- supplies the left ventricle Left circumflex artery- supplies the left atrium and left ventricle (aortic sinus)

Question 48

Describe the coronary circulation venous drainage

Answer 48

5 tributaries Converge at coronary sinus Drain into RA between atrioventricular orifice and orifice of IVC

Question 49

Name the 5 tributaries of coronary venous drainage

Answer 49

``` Greta Cardiac vein Small cardiac vein Middle cardiac vein Left marginal vein Left posterior ventricular vein ```

Question 50

What is an auricle?

Answer 50

Wrinkled pouch like structures | Increase capacity of atrium and increase volume of blood able to contain

Question 51

What are the differences between the left and right ventricles?

Answer 51

Left ventricle- thicker walls, longer conical cavity, finer more numerous trabeculae carne, larger papillary muscles

Question 52

Where do we auscultate valves?

Answer 52

1. The fifth intercostal space at approximately one cm medial to the mid-clavicular line. This corresponds to the mitral valve. 2. The fourth intercostal space, at the lower left border of the sternum. This corresponds to the tricuspid valve. 3. The second right intercostal space corresponds to the aortic valve. 4. The second left intercostal space corresponds to the pulmonary valve.