Lecture 30 - Heart Anatomy 1

Label the following veins.

1. Anterior Cardiac Veins 2. Coronary Sinus 3. Small Cardiac Vein 4. Middle Cardiac Vein 5. Oblique Vein of the Left Atrium 6. Great Cardiac Vein

Label the following image.

1. Arch of the Aorta 2. Superior Vena Cava 3. Sinoatrial Nodal Artery 4. Right Pulmonary Veins 5. Right Coronay Artery 6. Atrioventricular Nodal Artery 7. Posterior Interventricular Artery 8. Marginal Artery 9. Anterior Interventricular Artery 10. Circumflex Branch of the left Coronary Artery 11. Left Coronary Artery 12. Left Pulmonary Artery

Label the following picture

1. Brachiocephalic Trunk 2. Right Brachiocephalic Vein 3. Phrenic Nerve 4. External Jugular Vein 5. Subclavian Artery and Vein 6. Superior Vena Cava 7. Phrenic Nerve and Pericardiacophrenic Artery and Vein 8. Pericardium 9. Phrenic Nerve and Pericardiacophrenic Artery and Vein 10. Vagus Nerve (cranial nerve 10) 11. Internal Jugular Vein 12. Left Brachiocephalic Vein 13. Left Common Carotid Artery

Label the following veins.

1. Great Cardiac Vein 2. Left Marginal Vein 3. Left Posterior Ventricular Vein 4. Middle Cardiac Vein 5. Small Cardiac Vein 6. Coronary Sinus

What are the three most common coronary arteries involved in myocardial infarction?

1. Left Anterior Descending Coronary Artery 2. Right Coronary Artery 3. Left Circumflex Coronary Artery These are the three most common arteries involved in heart attacks (starting with the most common).

What is atherosclerosis?

Hardening of the arteries due to plaque buildup. Atherosclerosis can contribute to ischemia and myocardial infarction.

What cell type composes the majority of the heart's tissue?

Myocytes.

Define: mediastinum.

The central cavity of the chest. The mediastinum contains (most notably) the heart. Parts of the esophagus, trachea, and the thymus run through the mediastinum.

In what percentage of people is the Atrioventricular Nodal Artery supplied by the right coronary artery?

80-85%. This includes those with balanced hearts (about 30%) and those with right dominant hearts (about 50%).

What do we mean when we say that a patient has a "balanced" heart? What percentage of the population has a "balanced" heart?

A balanced heart is a heart whose arteries look exactly like the schematic. The left coronary artery and its branches go where they should go, supplying the tissues that they should supply. Similarly, the right coronary artery and its branches go where they should go and supply the expected tissues. Only about 30% of the population has a balanced heart.

In an average person, how many times does the heart beat per day?

About 100,000 beats. That's a lot.

What nerves innervate the pericardium?

Afferent fibers that run with the phrenic nerve. These carry sensory information for both the diaphragm and the pericardium.

At what vertebrae is the mediastinal compartment divided into superior and inferior mediastinum?

At about T5. This is roughly the level of the top of the heart.

In liters per minute, what is the average cardiac output of the heart?

Between 5 and 30 liters per minute. Over a lifetime, this is like running a faucet completely open for 45 years.

Label the following picture (arteries/veins).

1. Right Coronary Artery 2. Small Cardiac Vein 3. Circumflex of the Left Coronary Artery 4. Coronary Sinus 5. Middle Cardiac Posterior Interventricular Vein 6. Posterior Interventricular Branch (posterior descending) 7. Anterior Interventricular Branch (left anterior) 8. Great Cardiac (anterior interventricular) Vein 9. Circumflex Branch of the Left Coronary Artery 10. Left Coronary Artery

Label the following picture.

1. Sinoatrial Nodal Artery 2. Right Coronary Artery 3. Right Marginal Artery 4. Posterior Interventricular Artery 5. Diagonal Artery 6. Atrioventricular Nodal Artery 7. Left Marginal Artery 8. Anterior Interventricular Artery 9. Circumflex Branch of the Left Coronary Artery 10. Left Coronary Artery 11. Pulmonary Trunk 12. Arch of the Aorta

Label the following picture

1. Superior Vena Cava 2. Sinoatrial Artery 3. Right Coronary Artery 4. Inferior Vena Cava 5. Marginal Artery 6. Small Cardiac Vein 7. Great Cardiac Vein (with anterior interventricular artery) 8. Anterior Interventricular Artery 9. Great Cardiac Vein (with circumflex) 10. Circumflex Artery of the Left Coronary Artery 11. Left Coronary Artery 12. Pulmonary Artery 13. Left Subclavian Artery 14. Left Common Carotid Artery 15. Brachiocephalic Artery 16. Aorta

Heart Disease is one of the leading killers in the US. Why doesn't evolution select against those who do not have anastamoses among their coronary arteries?

By the time a person is suffering from heart disease, they are typically older (the average age for a heart attack is in the sixties for men). Because of the relatively late onset of most cardiovascular disease, individuals with poor anastamoses (which is pretty much all of us) already have progeny. For this reason, evolution doesn't select against anastamoses-less individuals.

What is angina?

Chest pain.

In what direction does the apex of the heart point?

Down (slightly) and to the left.

What is endocardium?

Endocardium is the simple squamous epithelium that lines the heart plus a little bit of underlying connective tissue. The endocardium is very thin.

True or false: 2/3 of the anterior aspect of the heart is (typically) the left ventricle.

False. 2/3 of the anterior aspect of the heart (looking at the heart from the front) is the right ventricle.

True or false: the heart is contained in the anterior mediastinal compartment.

False. The heart is part of the middle mediastinal compartment.

True or false: obviously, the apex of the heart is the part closest to the head.

False. Weirdly, the apex of the heart is actually in the lower part of the heart.

What is the fibrous membrane that covers the heart? What is the serous membrane that covers the heart?

Fibrous - the outer portion of the pericardium. It is tougher, less flexible, and provides more support than the serous membrane. Serous - the inner portion of the pericardium. It is more flexible, more fluid, and less supportive than the fibrous layer of the pericardium.

What is is cardiac tamponade? What are its affects on cardiac output, arterial blood pressure, and venous blood pressure.

For some reason or another, the pericardium is either filling with blood or something else. The fibrous layer of the pericardium won't stretch. Pressure mounts on the heart. Eventually, the pressure becomes great enough to force vessels to shut. Cardiac output falls, arterial blood pressure falls, and venous pressure rises.

What is the clinical relevance of the transverse sinus?

If, during a surgery, etc. Cardiac output must be stopped, the transverse sinus is where ligatures should be placed.

What is the clinical relevance of the oblique sinus?

If, for some reason, you need to stop venous return into the heart (maybe during a surgery to remove a lung), the oblique sinus is the right place for ligatures.

What do we mean when we say that a patient has a "Right-Dominant" heart? What percentage of the population has a "Right-Dominant" heart?

In a "right dominant" heart, a significant amount of the blood flow to the left ventricle is supplied by the right coronary artery, rather than the left coronary artery. In other words, the right coronary artery is doing more than it would in a balanced heart and the left coronary artery is doing less. About 50% of the population has a right dominant heart.

What do we mean when we say that a patient has a "Left-Dominant" heart? What percentage of the population has a "Left-Dominant" heart?

In a left dominant heart, the circumflex branch of the left coronary artery supplies blood flow to parts of the right ventricle. In this case, perforating branches of the left coronary artery will also supply the Atrioventricular Nodal Artery. About 20% of the population has a left dominant heart.

Under challenging circumstances (few bypass possibilities remaining) how do heart surgeons use the Thebesian Veins?

In extreme cases (when no bypass options are available) surgeons can take measures to divert oxygenated blood into this system, which can feed the heart.

Describe myocardial infarction. What causes it? What effect does it have on the myocytes of the heart?

Myocardial infarction is the death of the heart's myocytes. These myocytes, should the individual survive, will be replaced with connective tissue. Myocardial infarcation is caused by thrombus (blood clot) or embolism (dislodged thrombus or broken plaque) that blocks blood flow to heart tissue. Myocardial infarction can often cause death.

What is ischemia?

Narrowing of the arteries, often though a pathological process like atherosclerosis or blood clotting that causes inadequate blood/nutrient supply to an organ.

What drug is often used to treat angina?

Nitroglycerin.

What vessels carry blood away from the heart (outflow)? What vessels carry blood into the heart (inflow)?

Outflow - Aorta, pulmonary arteries Inflow - Vena Cavae, pulmonary veins

Histologically speaking, what kind of epithelium lines the heart?

Simple, squamous epithelium.

True or false: in some people the left circumflex artery is actually a branch of the right coronary artery.

Strangely yes, that is true. See the attached image. Needless to say, this is pretty unusual.

What is the name of the heart's groove that separates the atria and ventricles?

The Atrioventricular groove (or sulcus). It is also commonly called the coronary groove.

What is the name of the heart's groove that separates the right and left ventricles on the anterior side of the heart?

The anterior ventricular groove.

What is the oblique sinus of the heart?

The oblique sinus of the heart is the area lying posterior to the heart within the pericardial sac. The oblique sinus is bounded on the right by the inferior vena cava and the right pulmonary veins. The oblique sinus is bounded on the left by the left pulmonary veins.

What tissue is supplied/drained by the Pericardiacophrenic artery and vein.

The pericardium.

All of the great vessels that enter and leave the heart must pass through what barrier?

The pericardium. Many of these vessels are actually lined by the pericardium themselves.

What is the transverse sinus? Note the thick, black arrow (hard to see) in the attached image.

The transverse sinus is the space between the inflow and outflow vessels of the heart.

What are Thebesian Veins (vena cordis minimae)? Why are they significant?

These are veins that collect blood from coronary arteries and their branches and dump them back into the heart (back into circulation) instead of the superior or inferior vena cavae. It's almost like the blood is taking a short cut. This means that, in some cases, small amounts of deoxygenated blood will be dumped directly into circulation. Because of the quantity of blood pumped by the heart, this is completely okay.

When blood flow to one of the coronary arteries is compromised, which anastamosis is used to restore normal blood flow?

Trick question. Crazily, the heart doesn't really have anastamoses between the coronary arteries. This is part of why a heart attack is so serious. When blood flow is compromised, but not blocked, the heart begins increasing the size of its capillary-sized anastamoses between coronary arteries.

True or false: the pulmonary veins carry oxygenated blood, while the pulmonary arteries carry deoxygenated blood.

True. Pulmonary arteries take blood from the right ventricle into the lungs. This blood will be oxygenated, then returned to the left ventricle (via the pulmonary veins) to be pumped into systemic circulation.

True or false: the epicardium and the visceral membrane surrounding the heart are the same thing.

True. The visceral membrane is synonymous with the epicardium.