heart and great vessels Flashcards
what gland is located in the anterior mediastinum?
thymus gland - immune system, active in children not really in adults
what are the 5 surfaces of the heart and their composition?
anterior/sternocostal = right ventricle
posterior (base of the pyramid) = left atrium
inferior/diaphragmatic = left and right ventricles
right pulmonary = right atrium
left pulmonary = left ventricle
what are the 4 borders of the heart?
right = 3rd costal cartilage 1cm lateral to right border of the sternum
to the 6th costal cartilage 1 cm lateral to right of sternum again (mostly right atrium)
left = 2nd intercostal space, left border of sternum, to the
5th intercostal space just medial to midclavicular line (apex)
inferior = 6th costal cartilage 1 cm lateral to right of sternum, going across, through the xiphisternal joint, to the 5th intercostal space 3 cm left of the sternum
superior = Just inside the 2nd intercostal space on the left of the sternum, quite close to sternal border
where is the apex of the heart?
5th intercostal space medial to the midclavicular line, mostly made up of left ventricle
base of the heart - how is it easily identifiable?
sits posteriorly, mostly left atrium, identifiable by the pulmonary veins
what are the three sections of the aorta?
ascending aorta, aortic arch and descending aorta
what are the three branches of the aortic arch?
left subclavian artery (below clavicle, goes to upper limb)
left common carotid artery (neck)
brachiocephalic artery/trunk (which splits into right subclavian and right common carotid arteries)
what drains into the superior vena cava?
It is a union of the right and left brachiocephalic veins, so is filled with blood from the arms (subclavian veins) and head (internal jugular veins)
pulmonary trunk - what does it split into and where?
coming from the right ventricle, the P. trunk bifurcates at T4 into the two pulmonary arteries
aortic arch also at this level i think
pulmonary veins?
2 right ones and 2 left ones, all going into the left atrium at the posterior/back of the heart
what forms the inferior vena cava?
left and right iliac veins
describe direction of blood flow in the heart, including details on valves
Deoxygenated - comes in from superior and inferior vena cava, as well as coronary sinus, all into RA
Opens tricuspid valve and blood enters RV
From RV blood enters pulmonary trunk (via pulmonary valve) which splits into R and L pulmonary arteries
Oxygenated blood returns to LA via the four pulmonary veins
Fills and contracts, mitral/bicuspid valve opens (try before you buy)
Blood enters LV, contracts, aortic valve opens, blood goes from aorta to rest of the body
what are the 4 auscultatory zones, including position?
Aortic - to hear this valve, listen at the 2nd intercostal space, just by the right edge of the sternum
Pulmonary - 2nd intercostal space, just left of the sternum
R AV (tricuspid) - 4th intercostal space, left sternal border
L AV (bicuspid/mitral) - 5th intercostal space, left midclavicular line
what features are unique to the right atrium?
fossa ovalis - a depression, remanent of the foramen ovale
crista terminalis - a smooth ridge running, next to the pectinate muscles, as if running between the two vena cavas
what are the pectinate muscles?
muscular ridges found in both right and left atria
describe the features of the right and left ventricles
Trabeculae carneae = muscular ridges
Papillary muscles (post and ant) connect to AV valve by chordinae tendinae
If papillary muscle contracts it pulls a valve and closes the cusps, preventing valve going back into atrium, preventing backflow/eversion (so they contract when the ventricles contract)
fossa ovalis - what is it?
a remnant of the foramen ovale, was used to bypass blood from the lungs as it does not need to be oxygenated as a foetus, just goes RA to LA
what is the ligamentum arteriosum?
connects the aortic arch to the pulmonary artery
it was the ductus arteriosum in a foetus and is for bypassing the lungs, it shuts a few weeks after birth
what happens if the ductus arteriosum doesn’t close?
PDA - patent ductus arteriosus, causing a mixing of oxygenated and deoxygenated blood between aortic arch and pulmonary artery, weakening muscles and causing high pressure in the lungs
where do the coronary arteries arise from?
the ascending aorta, they then run around the coronary groove to branch to both atria and ventricles, first we have right and left coronary arteries
right coronary artery - what does it supply?
what are it’s branches?
mostly supplies right atrium and ventricle
splits into the right marginal artery (which supplies lateral RV) and the posterior interventricular/descending artery (PDA) which supplies septum and part of RV
left coronary artery - what are its branches and what do they supply?
Branches into the circumflex artery (as above) and the anterior interventricular artery/ left anterior descending artery (anterior of LV) (LAD)
what is meant by a right dominant heart?
80-85% of hearts are right dominant
Right dominant means the posterior interventricular artery arises from the right coronary artery and, therefore, the posterior wall of the left ventricle receives most of its blood supply from the right coronary artery
what is meant by a left dominant heart?
10% are left dominant
Left dominant means the posterior interventricular artery arises from the left circumflex artery, meaning the left coronary artery supplies cost of the blood to the posterior wall of the left ventricle
what is meant by a co-dominant heart?
Co-dominance is also an option, seen around 20% of the time, when the posterior interventricular artery is supplied by branches from both the right and left coronary arteries
what is the coronary sinus?
it receives blood from the cardiac veins, taking it to the right atrium as it is deoxygenated
it is located on the coronary sulcus, at the back of the heart between left atrium and ventricle
describe the conduction system of the heart
SAN (in RA at top of crista terminalis) is where impulse begins, spreads across atria and causes them to contract
AVN (near opening of coronary sinus in RA)
spreads down interventricular septum, splits into R and L atrioventricular bundles (bundles of HIS)
R AV bundle enters the septomarginal trabecula (a moderator band to do with vlalve contraction)
purkinje fibres, ventricles contract
where is the moderator band?
also known as the septomarginal trabecula, it is located in the right ventricle, on the intraventricula wall/spetum - dont confuse it with a papillary muscle, it is not attached to chordinae tendinae
features of a heart on posterior/anterior X ray
how to identify the coronary arteries
pay attention to the names (they were made while looking at the front view of the heart)
left coronary artery is quite short before actually branching, the branch that goes right down the middle (when looking from the front) is the left IV artery. the other branch going round the back, sticking near the top, is the left circumflex artery, which gives rise to the left marginal artery which marks the left ‘margin’ you can see
the right coronary artery is a bit longer before it branches, running along the top before giving rise to the right marginal artery which outlines the bottom right ‘margin’ visible form the front
right coronary artery also gives rise to the PDA as well but this goes round the back I think
