Heart continued

Question 1

Describe the internal jugular veins?

Answer 1

Blood drains from the head and neck via the jugular system.
Blood from the brain drains into the internal jugular vein, which passes directly downwards behind sternocleidomastoid, to join with the subclavian veins and form the brachiocephalic veins, just superior to the 1st rib (level of T2).
As you can see on the cadaver, the left brachiocephalic vein passes across the midline over the arch of the aorta
The external jugular veins drain the face and scalp and pass over the top of SCM, draining into the subclavian veins distal to their junction with the internal jugular veins.
The SVC terminates at the lower edge of the right 3rd costal cartilage whereby it enters the right atrium.
The two brachiocephalic veins join to form the Superior Vena Cava at the level of T3, posterior to the lower edge of the 1st CC

Question 2

Describe the valves of the heart?

Answer 2

There are 4 valves, the purpose of which are to prevent backflow of blood:
Atrioventricular:
Between the right atrium and right ventricle: tricuspid valve (3 cusps/leaflets)
Between the left atrium and left ventricle: mitral valve (2 cusps/leaflets)

Semilunar (do not have tendons like the atrioventricular valves):
Between the right ventricle and pulmonary artery: pulmonic valve (3 cusps/leaflets)
Between the left ventricle and aorta: aortic valve (3 cusps/leaflets)

Question 3

what are the heart valve locations?

Answer 3

The valves can be auscultated at 4 places
Aortic - Right sternal edge 2ndintercostal space;
Pulmonary - Left sternal edge 2ndintercostal space;
Tricuspid - Left sternal edge 5thintercostal space;
Mitral - Mid-clavicular line 5th intercostal space.

Question 4

how can blood enter the heart?

Answer 4

Blood enters through one of 3 vessels: SVC, IVC, coronary sinus (returning blood from the walls of the heart itself)

Question 5

At what vertebral levels does the brachiocephalic veins join to form the superior vena cava?

Answer 5

level of T3, posterior to the lower edge of the 1st CC.

Question 6

Describe the number of cusps in the valves of the heart?

Answer 6

There are 4 valves, the purpose of which are to prevent backflow of blood:
Atrioventricular:
Between the right atrium and right ventricle: tricuspid valve (3 cusps/leaflets)
Between the left atrium and left ventricle: mitral valve (2 cusps/leaflets)
Semilunar (do not have tendons like the atrioventricular valves):
Between the right ventricle and pulmonary artery: pulmonic valve (3 cusps/leaflets)
Between the left ventricle and aorta: aortic valve (3 cusps/leaflets)

Question 7

what information can auscultation for the valves give?

Answer 7

Auscultating for the valves gives us useful information about their potential pathologies, we’re specifically listening out for murmurs. Murmurs are extra sounds heard between S1 and S2. Generally speaking, there are two types of valve pathologies – regurgitation (can think of this is a leaky, dilated valve) and stenosis (can think of this is a tightened, smaller valve which struggles to open). Regurgitation and stenosis are heard as murmurs during auscultation.

Question 8

Explain the mechanism in which the right ventricle valves prevent backflow of blood?

Answer 8

There are 3 cusps of the tricuspid valve – anterior, septal and posterior - named relative to their positions in the right ventricle
The cusps have projections called chordae tendinae (which are fibrous like cords), which attach to papillary muscles within the ventricle wall.
As the ventricle contracts - to force blood out the pulmonary artery - the papillary muscles contract and pull on the chordae tendinae, this prevents eversion of the tricuspid valve cusps
Essentially, the papillary muscles and chordae tendinae keep the valve closed during ventricular contraction
Pulmonary valve:
Each semilunar cusp forms a pulmonary sinus
After ventricular contraction, the recoil of the blood fills these sinuses and forces the cusps closed – preventing backflow into the right ventricle

Question 9

Describe how the valves work on the left ventricle?

Answer 9

Aortic valve:
The valve is similar in structure and function to the pulmonary valve (note that instead of a anterior cusp as found in the pulmonary valve, the aortic valve has a posterior cusp)
The right and left coronary arteries originate from the corresponding aortic sinuses
The method of recoil and prevention of backflow by closing the aortic sinuses is the same as in the pulmonary valve, however in the aortic valve, the recoil automatically forces blood into the coronary arteries