heart and great vessels

Question 1

what gland is located in the anterior mediastinum?

Answer 1

thymus gland - immune system, active in children not really in adults

Question 2

what are the 5 surfaces of the heart and their composition?

Answer 2

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

Question 3

what are the 4 borders of the heart?

Answer 3

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

Question 4

where is the apex of the heart?

Answer 4

5th intercostal space medial to the midclavicular line, mostly made up of left ventricle

Question 5

base of the heart - how is it easily identifiable?

Answer 5

sits posteriorly, mostly left atrium, identifiable by the pulmonary veins

Question 6

what are the three sections of the aorta?

Answer 6

ascending aorta, aortic arch and descending aorta

Question 7

what are the three branches of the aortic arch?

Answer 7

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)

Question 8

what drains into the superior vena cava?

Answer 8

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)

Question 9

pulmonary trunk - what does it split into and where?

Answer 9

coming from the right ventricle, the P. trunk bifurcates at T4 into the two pulmonary arteries

aortic arch also at this level i think

Question 10

pulmonary veins?

Answer 10

2 right ones and 2 left ones, all going into the left atrium at the posterior/back of the heart

Question 11

what forms the inferior vena cava?

Answer 11

left and right iliac veins

Question 12

describe direction of blood flow in the heart, including details on valves

Answer 12

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

Question 13

what are the 4 auscultatory zones, including position?

Answer 13

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

Question 14

what features are unique to the right atrium?

Answer 14

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

Question 15

what are the pectinate muscles?

Answer 15

muscular ridges found in both right and left atria

Question 16

describe the features of the right and left ventricles

Answer 16

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)

Question 17

fossa ovalis - what is it?

Answer 17

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

Question 18

what is the ligamentum arteriosum?

Answer 18

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

Question 19

what happens if the ductus arteriosum doesn’t close?

Answer 19

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

Question 20

where do the coronary arteries arise from?

Answer 20

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

Question 21

right coronary artery - what does it supply?
what are it’s branches?

Answer 21

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

Question 22

left coronary artery - what are its branches and what do they supply?

Answer 22

Branches into the circumflex artery (as above) and the anterior interventricular artery/ left anterior descending artery (anterior of LV) (LAD)

Question 23

what is meant by a right dominant heart?

Answer 23

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

Question 24

what is meant by a left dominant heart?

Answer 24

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

Question 25

what is meant by a co-dominant heart?

Answer 25

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

Question 26

what is the coronary sinus?

Answer 26

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

Question 27

describe the conduction system of the heart

Answer 27

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

Question 28

where is the moderator band?

Answer 28

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

Question 29

features of a heart on posterior/anterior X ray

Question 30

how to identify the coronary arteries

Answer 30

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