Clinically Relevant Anatomy of the Heart

Question 1

describe phrenic nerves

Answer 1

motor nerves that supply the diaphragm
run anterior to the lungs
descend across the lateral borders of the pericardium

vagus nerve runs posterior to lung

Question 2

describe the anatomy of the pericardium

Answer 2

fibrous pericardium - tough, outermost layer of the heart

serous epicardium - thin layer, secretes pericardial fluid into pericardial cavity. Divided into 2 separate layers - parietal pericardium and visceral pericardium (epicardium)

pericardial cavity - space between parietal and visceral pericardium

Question 3

describe cardiac tamponade

Answer 3

when the pressure around the heart can prevent cardiac contraction

Question 4

describe haemopericardium

Answer 4

when pericardial cavity fills with blood

Question 5

describe the process of pericardiocentesis

Answer 5

drainage of fluid from the pericardial cavity

needle is inserted via the infrasternal angle and directed superoposteriorly, aspirating continuously

Question 6

describe the transverse pericardial sinus

Answer 6

space between pericardial cavity, posterosuperiorly (between the great vessels)
lies posterior to the ascending aorta and pulmonary trunk, anterior to the superior vena cava (most proximal segments of these vessels are enclosed in the pericardium, which blends with their adventitia a little further distally)
used by cardiac surgeons to identify and isolate great vessels to commence cardiopulmonary bypass

Question 7

identify the openings of all the great vessels once the heart has been removed

Answer 7

diagram

Question 8

describe the orientation of the heart

Answer 8

surfaces;
anterior (sternocostal)
base (posterior)
inferior (diaphragmatic)

borders;
right (lateral)
left (lateral)
inferior 
superior 

apex (on the left) - 5th intercostal space, left of sternum - cardiac enlargement (cardiomegaly) may sift apex beat to left

Question 9

describe the anterior surface of the heart

Answer 9

must refer to PP

auricles - extensions of the atrium that allow for maximal filling

Question 10

describe the base and diaphragmatic surface of the heart

Answer 10

must refer to PP
coronary sinus is the veins which differentiate the base (left atrium) and the apex (inferior diaphragmatic surface) of the heart

Question 11

describe the coronary arteries and their ranches

Answer 11

first thing to arise from the ascending aorta
supply the epicardium and myocardium
vessels come just deep to the epicardium, embedded in adipose tissue

right coronary artery - right atrio-vetricular grove - branches to the right marginal artery and posterior interventricular artery

left (main stem) coronary artery - atrio-ventricular groove between pulmonary trunk and left auricle - much shorter than the right coronary artery, branches to circumflex artery, left anterior descending, this then has its own branch, left marginal artery and lateral branch

Question 12

describe the coronary sinus

Answer 12

a short venous conduit (found in atrioventricular groove posteriorly) which receives deoxygenated blood from most of the cardiac veins and drains into the right atrium

Question 13

describe septum wall

Answer 13

internal wall that divides the heart into a right and left side
2 parts;
part between the 2 atria - inter-atrial septum (indicated by inter-atrial groove)
part between 2 ventricles - inter-ventricular septum (indicated by inter-ventricular groove)

Question 14

describe defects in the septum

Answer 14

hole in the inter-atrial or inter-ventricular septum
allows for the mixing of arterial and venous blood in the heart - life threatening as it reduces the oxygen content of systemic arterial blood in the aorta => hypoxaemia

Question 15

describe the inferior of the right atrium

Answer 15

must refer PP

Question 16

explain how the pump ensure unidirectional flow

Answer 16

4 cardiac valve, one valve at the exit of each cardiac chamber

leaflet design - cusps are flat (contain papillary muscles)
tricuspid - 3 cusps (anterior, posterior and septal)
mitral - 2 cusps (anterior and posterior)

semilunar design - cusps are like cups
aortic - 3 cusps (right, left and posterior). Also has sinuses (spaces within the cusps), from which the coronary arteries arise
pulmonary - 3 cusps (anterior, right and left)

papillary muscles - attached to chamber walls (extend from ventricles) and prevent prolapse of the mitral and tricuspid valves ventricular during contraction

Question 17

describe the inferior of the ventricles

Answer 17

refer to PP
moderator band - extension of tissue carrying fibres of right bundle branch to the papillary muscle of the anterior cusp to allow for coordinated contraction of the papillary muscles of tricuspid valve
the fibrous skeleton surrounding the valves allows for electrical conduction

Question 18

describe inferior of left atrium

Answer 18

refer PP