Middle Mediastinum

Question 1

Why is the pericardial sinus important?

Answer 1

deliniates aorta and pulmonary trunk, and diverts blood flow if something is placed in there. surgeon then has bloodless field in which to work.

Question 2

P wave represents?
QRS complex?
T wave?

Answer 2

P wave- atrial depolarization
QRS complex- ventricular depolarization
T wave- ventricular repolarization

Question 3

Explain the electrical aspect of the P wave. 
PR  interval?
QRS interval?
ST interval?
T wave?

Answer 3

P wave- SA node fires, atria contract, pulse sent to AV node
PR interval- AP is delayed at AV node, and depolarization of atria continues
QRS interval- Ventricular depolarization
ST segment- Beginning of ventricular repolarization.
T wave- ventricular repolarization.

Question 4

What is the base of the heart?

Answer 4

The left atrium.

Question 5

What makes up the diaphragmatic surface of the heart?

Answer 5

The ventricles.

Question 6

Where do the aorta, inferior vena cava, and esophagus pierce the diaphragm?

Answer 6

Inferior vena cava- T8
esophagus- T10
Aorta- T12

Question 7

What is the auricle of the heart, and what is its purpose?

Answer 7

Small muscular flap that increases blood flow capacity of the atrium.

Question 8

What is the sinus venarum, and where is it?

Answer 8

It is a smooth surface on the posterior wall where the superior and inferior vena cava empty in to.

Question 9

Where is the crista terminalis and what is it?

Answer 9

origin of the pectinate mm, on the anterior wall.

Question 10

What is the sulcus terminalis?

Answer 10

External feature that marks the (internal) crista terminalis.

Question 11

Where exactly is the SA node located?

Answer 11

At superior aspect of sulcus terminalis, and lateral/inferior to the opening of the superior vena cava.

Question 12

Where is the fossa ovalis, and what was it in the fetus?

Answer 12

It is in the interatrial wall, and was the foramen ovale in the fetus.

Question 13

What are the muscle ripples called in the ventricles?

Answer 13

Trabeculae carnae

Question 14

What is the supraventricular crest?

Answer 14

separates the conus arteriosus from the rest of the right ventricle (separates inflow and outflow tracts)

Question 15

What do the chorda tendinae attach to in the right ventricle?

Answer 15

The anterior, posterior, and septal cusps.

Question 16

What is at the apex of the conus arteriosis? What level is this at?

Answer 16

The pulmonary valve. at the level of 3rd costal cartilage.

Question 17

What is the aortic vestibule? How is it oriented anatomically?

Answer 17

Outflow area from left ventricle. Located antero-superior.

Question 18

explain the point of papillary muscles

Answer 18

during ventricular systole, pressure in the atria is very low. Blood would backflow, but the papillary mm contract to keep the AV valves closed.

Question 19

What is stenosis, and what happens? (mitral/aortic valve stenosis)

Answer 19

valve does not open fully, so less blood flows out of chamber.

Question 20

What is insufficiency/regurgitation, and what happens?

Answer 20

Valve fails to close completely, so some blood goes back into previous spot.

Question 21

What is a heart murmur?

Answer 21

Extra/unusual heart sound. Can be innocent or abnormal.

Question 22

What does the RCA supply? (5-7)

Answer 22

The interventricular septum, left ventricle (diaphragmatic myocardium), right ventricle, right atrium, AV septum, and usually the SA and AV nodes

Question 23

Which coronary artery is usually dominant? What makes one dominant?

Answer 23

The RCA is usually dominant. Dominance decided by which gives rise to the posterior descending artery.

Question 24

Right coronary artery arises from? Gives what brr, and where? How does it travel? (include all the way to its anastomoses)

Answer 24

1. Arises from right aortic sinus and travels down AV groove
2. gives off marginal a. branch
3. courses to posterior of heart, and gives off AV nodal branch at the crux (where all 4 chambers meet)
4. Posteriorly, it gives off the posterior descending branch (posterior interventricular), which travels in posterior interventricular groove toward the apex of the heart.
5. Also gives off perforating brr to supply ventricles, and the IV septal br to supply the IV septum.
6. Continues to anastomose w/circumflex of the LCA.

Question 25

What does the right marginal br of the RCA supply?

Answer 25

right border of the heart as it approaches the apex, but does NOT supply the apex.

Question 26

The LCA courses b/w what?

How/where does it divide?

Answer 26

1. between pulmonary trunk and left auricle.
2. Under auricle, it divides into left anterior descending (LAD), and the circumflex a. May give off lateral (diagonal) branches as well.

Question 27

What does the LCA supply?

Answer 27

The left atrium and auricle, pulmonary artery, aortic root, and the majority of ventricular myocardium.

Question 28

What coronary veins drain into coronary sinus? Right atrium?

Answer 28

Great, middle, and small cardiac veins drain into coronary sinus.

smaller, more anterior cardiac veins drain directly into right atrium

Question 29

What does the great cardiac v travel with? To where?

Answer 29

with the LAD artery and circumflex artery, to the coronary sinus.

Question 30

Small cardiac vein travels with what?

Answer 30

With RCA, into coronary sinus

Question 31

Middle cardiac vein travels with what?

Answer 31

With posterior descending artery (posterior interventricular a), into coronary sinus

Question 32

Where is the AV node located?

Answer 32

In the interatrial septum near coronary sinus opening

Question 33

explain the pathway of the AP in the heart

Answer 33

SA node starts the AP, which spreads through atrial myocardium to the AV node

2. AV node sends AP to the ventricular myocardium via the AV bundle
3. AV bundle splits into right and left bundles at junction of muscular and membranous parts of the septum
4. The L/R AV bundles continue on both sides of IV septum, deep to endocardium, then branch into subendocardial brr called PURKINJE FIBERS.
5. Purkinje fibers extend into the walls of the ventricles

Question 34

Right bundle purkinje fibers innervate what specifically? 3

Answer 34

Muscle of IV septum, anterior papillary mm via moderator band, wall of right ventricle

Question 35

Left bundle purkinje fibers innervate what specifically? 4

Answer 35

IV septum, anterior and posterior papillary mm, wall of left ventricle

Question 36

sympathetic supply to heart: where do the sympathetic pre synaptic cell bodies come from? post synaptic?
Where do the post synaptic fibers end?

Answer 36

From the lateral horns of the superior 5 or 6 thoracic vertebrae.
Post synaptic cell bodies in cervical and superior cervical ganglia of sympathetic chain.
Fibers end in SA and AV nodes, and in coronary aa.

Question 37

What does sympathetic innervation to coronary aa do?

Answer 37

Dilates them by inhibiting constriction.

Question 38

Where is the cardiac plexus located?

Answer 38

On anterior surface of tracheal bifurcation

Question 39

Parasympathetic innervation to heart: Where are the presynaptic fibers?
Post synaptic fibers terminate where? What do they do?

Answer 39

Presynaptic fibers of vagus nerve. terminate in SA and AV nodes, and in coronary aa. Constrict coronary aa.

Question 40

What is cardiac tamponade? symptoms?

Answer 40

neck vv distended, in and out of shock, decreased BP, chest pain radiating to neck, shoulder, back, or abdomen. Pericardiocentesis required.

Question 41

where can a pericardiocentesis be performed?

Answer 41

1. 5th or 6th intercostal space

2. infrasternal angle (subxyphoid approach).

Question 42

mitral valve cusp names

Answer 42

anterior and posterior

Question 43

pulmonary valve cusps

Answer 43

anterior, left, right cusps

Question 44

aortic vavle cusps

Answer 44

posterior, left, right cusps