2. Anatomy of the Heart & Coronary Vessels Flashcards
What are the 4 functions of the pericardium?
Fixes heart in mediastinum
Protection from infections from other organs
Prevents excessive heart dilation
Lubrication
What is this?
Pericardial effusion leading to pericardial tamponade
Give 3 factors leading to cardiac tamponade.
- rate of accumulation
- fluid amount in pericardium
- compliance of pericardium
How can cardiac tamponade lead to MI?
CT from e.g. fluid amount in pericardium/accumulation rate -> increase in volume compresses atria, vena cava and pulmonary veins -> R ventricle collapse
OR
CT from e.g. fluid amount in pericardium/accumulation rate -> decreased R. ventricle filling in diastole, stroke volume and C.O.
What are A, B, C, D and E?
A: Endocardium
B: Myocardium
C: Epicardium
D: Atrioventricular valve
E: Branch of the coronary artery
Describe the flow of blood through the heart.
SVC, IVC, Coronary sinus -> R. atrium -> (tricuspid valve) -> R. ventricle -> (pulmonary semi lunar valve) -> pulmonary trunk -> pulmonary arteries to lungs -> pulmonary capillaries -> 4 pulmonary veins -> L. atrium -> (mitral valve) -> L. ventricle -> (aortic semi lunar valve) -> aorta -> (body) -> systemic capillaries -> veins -> heart
What is the coronary groove (atrioventricular sulcus)?
Oblique plane which seperates atria and ventricles
What are the (ant. and post.) interventricular grooves?
Overlie intervetricular septum which seperates L and R ventricles
Give 2 features of the R. ventricle.
Give 3 features of the L. ventricle.
R. ventricle: 2/3 anterior, pulmonary trunk
L. ventricle: apex (L. border), inferior surface (2/3 posterior), aorta
What are A, B, C, D and E?
A: R. atrium
B: R. ventricle
C: L. ventricle
D: Pulmonary trunk
E: ligamentim arteriosum
What are A - G?
A: auricle of LA
B: L ventricle
C: coronary sinus
D: PIG (post. interventricular groove)
E: R. ventricle
F: L. atrium
G: L pulmonary arteries
What are A-F?
A: coronary sinus
B: fossa ovalis
C: tricuspid valve
D: chordae tendinae
E: papillary muscles
F: trabeculae carnae
What are A-F?
A: SVC
B: fossa ovalis
C: IVC
D: coronary sinus
E: tricuspid valve
F: pectinate muscle
Where are the R. atrium and ventricle in relation to the L. atrium and ventricle?
R: right border and anterior surface
L: posterior or base of heart (plus thicker myocardium)
Label the coronary blood supply
A: L. coronary artery
B: R. coronary artery
C: mitral valve
Describe the coronoray artery supply.
RCA gives rise to post. interventricular artery and then anastomoses with circumflex branch of LCA
Anterior interventricular (LAD) loops around apex and anastamoses with post. interventricular artery
What are A-C?
A: Left Coronary Artery
B: L. circumflex
C: Anterior interventricular (LAD)
What coronary arteries are usually the cause of MI?
LAD (ant. interventricular) of LCA (40-50%)
RCA (30-40%)
LCA circumflex (15-20%)
What branches of coronary arteries supply AVN and SAN?
AVN: RCA & LAD
SAN: RCA
What is the path of coronary veins?
Collect waste from cardiac muscle -> drain to coronary sinus on post. heart -> R. atrium
The dense CT fibrous skeleton of the heart surrounds AV and outflow vessel valves. It merges with the interventricular septum. What are its 4 main functions?
- support valves
- prevent overstretching of valves
- insertion point of cardiac muscle bundles
- electrical insulator between atria and ventricles
What do valves do in diastole?
AV valves open. blood flows A -> V when vent. pressre < atrial pressure.
Chordae tendinae slack, papillary muscles relaxed.
SL valves closed.
What do the valves do in systole?
AV valves close preventing backflow (when vent. contract, pushes valve cusps closed).
Chordae tendinae taut, papillary muscles contract to pull chords.
Sl valves open.
How many cusps do semilunar valves have, and what are they?
- L coronary aortic sinus
- R. coronary aortic sinus
- Non-coronary aortic sinus
Describe the conduction system of the heart
SAN (pacemaker cells) impulses contract atria -> impulses pause 0.1s at AVN so ventricles fill -> AV bundle connects A & V -> AVN branches conduct impulse through interventricular septum -> purkinje fibres stimulate contractile cells of both ventricles, start at apex and move up
The heart is innervated by the cardiac plexus of nerves. Where it is located, and what does it contain?
It extends to coronary vasculature and components fo conducting system.
- Anterior to carina and posterior to aortic arch
- parasympathetic from vagus, sympathetic (from sympathetic trunk), visceral general afferents (VGA)
What is the path for cardiac sympathetic innervation?
Cardioacceleratory centre in medullary retiuclar formation
Preganglionic sympathetic neurons in thoracic spinal cord
Postganglionis sympathetic neurons to SAN, AVN and coronary vascular SM
Increase HT and contraction force
What is the path for cardiac parasympathetic innervation?
Cardioinhibitory centre in reticular formation in medulla
Vagus nerve to SAN and AVN
Slows HR
Pain is not felt in the heart - referred pain. Descrive the path of pain caused by ischaemia and damage to cardiac muscle.
Stimuates visceral sensory nerve endings in myocardium -> afferent ascends to CNS through cardiac branches of sympathetic trunk -> (organ and skin pain fibres travel together) -> interpreted as it if came from somatic areas e.g skin supplied by T1-5 L side of chest, neck, face and L. arm. Infarct on inferior wall referred to epigastrium T7-9.
