The heart and mediastinum Flashcards
Which 2 veins join to form the brachiocephalic veins?
Internal jugular veins and subclavian veins
The brachiocephalic veins are formed behind what?
The sternoclavicular joint
The brachiocephalic veins join to form what?
Superior vena cava
Where is the SVC formed?
Behind the right costal cartilage of rib 2
Which procedure involves both the venous system and liver biopsy?
Transjugular liver biopsy
What are the 3 main arteries that branch off the aortic arch in the superior mediastinum?
Brachiocephalic trunk
Left common carotid artery
Left subclavian artery
The ligamentum arteriosum is a remnant of what?
Ductus arteriosus
Which 2 structures did the ductus arteriosus join together?
Pulmonary trunk and aortic arch
What was the function of the ductus arteriosus?
Allowed blood to bypass the lungs during embryological development
What can happen if the ductus arteriosus fails to close after birth?
It results in a patent ductus arteriosus, which allows for mixing of low oxygenated blood from the pulmonary trunk with high oxygenated blood in the aorta, therefore decreasing the oxygen content of the blood heading towards systemic circulation
The internal thoracic arteries branch off from which arteries?
Subclavian arteries
The internal thoracic arteries can be grafted for use in which procedure? Why are these arteries particularly beneficial for this procedure?
CABG – coronary artery bypass graft
They resist atherosclerotic plaque build up
What happens to the thymus gland after childhood?
Atrophies
What surrounds the heart?
Pericardial sac
The fibrous pericardium is attached to what inferiorly?
Central diaphragmatic tendon
What are 2 things that are most likely to cause a blockage of the SVC?
Extrinsic compression by a tumour
Metastasis to mediastinal lymph nodes
Which levels of the sympathetic chain carry fibres to the heart?
T1 – T4
Why does cardiac pain occur in the T1 – T4 dermatomes, mainly on the left?
Cardiac visceral sensory fibres travel back to the CNS with the sympathetic nerves T1 – T4
What 2 layers is the pericardium composed of?
Fibrous pericardium
Serous pericardium
The parietal layer of the serous pericardium lines what?
The inside of the fibrous pericardium
The visceral layer of the serous pericardium lines and forms what?
The heart and forms the epicardium
What innervates the fibrous pericardium?
Phrenic nerve
Describe how a haemopericardium can lead to cardiac tamponade?
In a haemopericardium, blood accumulates in the pericardial sac. The fibrous pericardium is relatively inelastic, so blood in the sac can compress the heart and prevent it from being able to fill properly during diastole due to external compression – this is cardiac tamponade
What are the 2 sinuses of the heart?
Transverse pericardial sinus
Oblique pericardial sinus
What clinical manoeuvre can the transverse pericardial sinus be used for?
Can be used during cardiac surgery (e.g. coronary artery bypass graft) to pass a surgical clamp around the aorta and pulmonary trunk to control blood flow while on a heart-lung machine
Which 3 vessels deliver blood to the right atrium of the heart?
Superior vena cava
Inferior vena cava
Coronary sinus
Which valve does blood pass through as it passes from the right atrium to the right ventricle?
Tricuspid valve
At which point is the tricuspid valve closed?
During ventricular contraction / systole
What does the crista terminalis mark the boundary between?
The embryonic sinus venosus and primitive atrium
The anterior wall of the right atrium contains which muscles?
Pectinate muscles
Other than the anterior wall of the right atrium, where else in the right atrium are the pectinate muscles found and what pathology can occur in this structure?
Atrial appendage / auricle – a muscular pouch-like extension of the right atrium
In cases of atrial fibrillation, blood clots can form here
Which structure can be found on the interatrial septum of the right atrium? What is it a remnant of and what was its function?
Fossa Ovalis – a remnant of the foramen ovale, which allowed oxygenated blood to bypass the lungs and travel directly from the right atrium to the left atrium in foetal circulation
What is the smooth-walled region of the right ventricle which leads to the pulmonary valve and trunk?
Conus arteriosus / infundibulum
What are the prominent muscular ridges on the inner wall of the right ventricle called?
Trabeculae carnae
Which fibrous cords connect the valve leaflets to the papillary muscles in the right ventricle?
Chordae tendinae
In the right ventricle, what are the papillary muscles and what is their function?
Muscle projections that anchor the chordae tendinae and prevent valve prolapse during ventricular contraction
Which trabeculae carnae is essential for the rapid conduction of electrical impulses, where does it extend to and from, and what does it carry?
Moderator band – runs from the interventricular septum to the base of the anterior papillary muscle, and carries the right bundle of the atrioventricular bundle
The left atrium receives oxygenated blood from how many pulmonary veins?
4
Which valve does blood pass through as it passes from the left atrium to the left ventricle?
Mitral valve
Describe when the papillary muscles do and do not contract.
The papillary muscles contract when the ventricles contract to prevent the cusps from being blown back into the atria during ventricular systole
They do not contract to open the valves – the valves open passively
Describe the composition of the cardiac skeleton.
Dense collagen fibres that form a rigid, non-conductive framework
List the 3 functions of the cardiac skeleton.
Mechanical stability
Attachment point for cardiac muscle and valve cusps
Electrical insulation
How many cusps do the aortic and pulmonary semi-lunar valves each have?
3
Name the 3 sections of the aortic valve.
Right coronary leaflet
Left coronary leaflet
Non-adjacent leaflet
Name the 3 sections of the pulmonary valve.
Right-adjacent leaflet
Left-adjacent leaflet
Non-adjacent leaflet
What are the 2 main pathologies that can affect the heart valves?
Stenosis and insufficiency (regurgitation)
Which 2 heart valves are most commonly affected by valvular heart diseases?
Mitral and aortic
What is the most common type of congenital heart disease in adults?
Mitral valve prolapse – one or both leaflets are enlarged, redundant, or floppy
What sign would you be able to pick up using a stethoscope on someone with mitral valve prolapse?
Late systolic murmur
What is the most frequent heart valve abnormality, what is it often caused by, and what does it result in?
Aortic stenosis – often the result of degenerative calcification, and results in left ventricular hypertrophy
In which circumstances might the tricuspid and pulmonary valves be affected by disease?
As the result of an infection – rheumatic fever or infective endocarditis
What sign could be seen on the nails of someone with right-sided valve disease?
Splinter haemorrhages
Where do the coronary arteries arise from?
Coronary sinuses
The main inflow of the coronary arteries is during which stage of contraction?
Diastole
List the 4 main branches of the right coronary artery.
Sinoatrial nodal artery
Anterior ventricular arteries
Right marginal artery
Inferior interventricular artery (arises from RCA in 60% of people)
List the 4 areas the right coronary artery supplies.
Right atrium + right ventricle
SA node + AV node
Conduction system up to AV bundles
Posterior 1/3rd of IV septum
List the 5 main branches of the left coronary artery.
Sinoatrial nodal artery (in some people)
Circumflex artery
Anterior interventricular artery (left anterior descending (LAD) artery)
Marginal artery
Inferior interventricular artery (arises from LCA in 40% of people)
List the 4 areas the left coronary artery supplies.
Left atrium + ventricle
AV bundle
Right + left bundle branches
Anterior 2/3rd of IV septum
What are the 3 main veins which drain the heart? What do they drain into?
Great, middle and small cardiac veins
Drain into the right atrium via the coronary sinus
