Structure Of Heart Flashcards
Apex beat:
Left 5th intercostal space, mid-clavicular line
Right heart border: SVC – right atrium
Left heart border: Aortic knuckle – left pulmonary artery – LA appendage – left ventricle
Anteriorly: mainly right ventricle
Posteriorly: mainly left atrium and pulmonary veins
Mediastinum- Area between right and left pleura, divided as follows:
Plane between sternal angle and T4/5 divides superior and inferior mediastinum
Pericardium divides anterior, middle and posterior mediastinum
Pericardium consists of fibrous (parietal) and visceral layers
Push your fist into a soft balloon – explains two layers and pericardial reflections
Pericardial space
Is a potential space
Cardiac tamponade
Rapid collection of pericardial fluid is restricted and impairs filling
Pleural reflection
allows drainage of pericardial fluid from the left of the xiphisternum
Atrioventricular valves (mitral and tricuspid)
are an intrinsic part of their ventricle
Disorders of the ventricle often affect function of the relevant Atrioventricular valve
Papillary muscles (part of ventricle)
attach to atrioventricular valves via chordae tendinae
Semilunar valves (aortic and pulmonary)
are an intrinsic part of their great artery
Disorders of the aorta or pulmonary artery often affect function of their respective valves
Arterial blood
is blood leaving the heart – not always fully oxygenated (PA)
Venous blood
is blood returning to the heart – not always deoxygenated (PV)
The pulmonary artery
carries deoxygenated blood from the heart
The pulmonary veins
carry oxygenated blood back to the heart
LV is thick walled and muscular (systemic ventricle)
RV has thin muscular wall
Atria are thin walled
Four pulmonary veins (usually 4) drain into the left atrium
Coronary sinus drains blood from the heart muscle into the right atrium
Right atrium has smooth (from sinus venosus) and trabeculated (from original atrium) portions
Crista terminalis separates smooth and trabeculated portions of right atrium
Fossa ovalis
is the remains of the foramen ovale which was patent in foetal life
Cardiac muscle cells cross link
They join at intercalated discs
Coronary arteries arise from the aortic root sinuses and supply the heart itself
Coronary arteries are epicardial and therefore accessible to the surgeon (bypass surgery)
Two main coronary arteries, left and right
Coronaries are functional end arteries
unless collateral supply has developed
The left main stem divides into left anterior descending (LAD) and circumflex (Cx) branches
- The LAD runs in the anterior interventricular groove
- The LAD gives off septal and diagonal branches to the septum and left ventricular myocardium
- The Cx runs in the left atrioventricular groove
- The Cx gives off obtuse marginal branches to the posterolateral LV wall
- In 10% the Cx provides the posterior descending artery (PDA)
The RCA runs in the right atrioventricular groove
Usually supplies sinus node, AV node and branches to the anterior RV wall
Distal RCA branches into posterolateral and posterior descending arteries (latter in about 70% of people)
The posterior descending artery runs in the posterior interventricular groove and supplies inferior septum and LV
Dominance refers to the artery (RCA or Cx) which supplies the posterior descending artery
Most people (70%) are right dominant – RCA supplies the PDA
About 20% are co-dominant – RCA and Cx both help supply the PDA
About 10% are left dominant – Cx supplies the PDA
