Mini 3 - Michigan Questions: Heart

During fetal development, there is a temporary opening between the right and left atria called the foramen ovale. This opening allows blood to bypass the lungs since the fetus receives oxygen from the mother's blood through the placenta. After birth, when the baby starts breathing on its own, the foramen ovale usually closes, allowing blood to flow normally through the heart and lungs. However, in some individuals, the foramen ovale may persist into adulthood, causing a condition known as a patent foramen ovale.

In a blunt trauma to the chest, the heart can be compressed between the sternum and the spine, causing damage to the heart chambers. The right ventricle is the most likely chamber to be damaged in this scenario because it is located closest to the sternum. The left atrium and left ventricle are located more posteriorly in the chest and are less likely to be affected by direct compression from the sternum. The right atrium is also more posteriorly located and is therefore less likely to be damaged compared to the right ventricle.

The mitral valve is best heard in the fifth left intercostal space. This is because the mitral valve is located between the left atrium and left ventricle of the heart, and the fifth left intercostal space is the area where the apex of the heart is located. The apex is the bottom tip of the heart and is the point where the mitral valve can be best auscultated.

If the blade had completely penetrated the sternocostal surface of the heart, the most likely heart chamber to have been opened would be the right ventricle. The right ventricle is located on the anterior surface of the heart, closest to the sternum.

The sternal angle is located at the level of the second rib. Therefore, when the medical student slid her fingers down to the sternal angle, her fingers were at the level of the second rib.

The left recurrent laryngeal nerve leaves the vagus nerve and loops under the arch of the aorta near the ligamentum arteriosum/ductus arteriosis. When performing surgery in this area, like the repair of a patent ductus arteriosis, a surgeon must be very careful to identify and preserve the left recurrent laryngeal nerve. If this nerve is damaged, it may lead to paralysis of the left vocal fold and cause hoarseness in the patient. This is a very significant complication that you want to remember!

The arch of the azygos vein is located on the right side of the body and would not be damaged by surgery near the aortic arch. The internal thoracic artery is a branch of the subclavian artery and is not near the ductus arteriosis.
The left phrenic nerve, which innervates the diaphragm, is lateral to the vagus nerve and would not be damaged in this procedure.
The left superior intercostal vein lies lateral to the vagus and aortic arch, so it would not be disturbed by surgery.

During ventricular systole, the ventricles contract and pump blood out of the heart. The aortic valve is responsible for allowing blood to flow from the left ventricle into the aorta, while the pulmonary valve allows blood to flow from the right ventricle into the pulmonary artery. Therefore, during ventricular systole, the aortic and pulmonary valves would be open to allow blood to be pumped out of the heart and into the respective arteries.

The best place to listen to heart valves is not at their actual sternocostal projections. If you place your stethoscope exactly where a valve is located, you may not hear anything because the valve might be deep in the chest or the sound might be muffled by bone or cartilage. Instead, you want to listen to the valves by putting your stethescope at a point downstream from the valve where you can hear the blood flowing and colliding with the muscular chest wall.

There are points of auscultation for all four heart valves: Pulmonic: left second intercostal space, lateral to the sternal angle; Aortic: right second intercostal space, lateral to the sternal angle;
Mitral: left fifth intercostal space, 8cm away from the midline;
Tricuspid: left fourth intercostal space, just lateral to the sternum.

Based on the location of the high-pitched sound in the second right intercostal space, just lateral to the edge of the sternum, the correct conclusion is that the stenosis is of the aortic valve. The aortic valve is typically heard in this area during auscultation, and a high-pitched sound suggests narrowing or stenosis of the valve.

The oblique sinus is an area of the pericardial cavity located behind the left atrium of the heart where the serous pericardium reflects onto the inferior vena cava and pulmonary veins. If you slide your fingers under the heart, they will be in the oblique sinus. The other pericardial sinus that you should be familiar with is the transverse sinus. The transverse sinus is an area of the pericardial cavity located behind the aorta and pulmonary trunk and anterior to the superior vena cava. It separates the outflow vessels from inflow vessels.

The coronary sinus is the large vein on the posterior surface of the heart which drains into the right atria. It receives blood from the great, middle, and small cardiac veins, the oblique vein of the left atrium, and the left posterior ventricular vein.
The coronary sulcus is the groove on the heart which separates the atria from the ventricles. Many arteries and veins run in this sulcus.
The costomediastinal recess is an area in the pleural sac where the costal pleura changes to the mediastinal pleura.

Blockage of the anterior interventricular (descending) artery would lead to ischemia of the apex of the heart. This artery, also known as the left anterior descending artery, supplies blood to the anterior wall of the left ventricle, including the apex. Ischemia occurs when there is a reduced blood flow to a particular area, leading to a lack of oxygen and nutrients. Therefore, if this artery is blocked, the apex of the heart will not receive adequate blood supply, resulting in ischemia.

The heart has three important surfaces: an anterior surface, a diaphragmatic surface, and a pulmonary surface. The anterior surface, or sternocostal surface, is mostly made up of the right ventricle. The diaphragmatic surface is mostly the left ventricle, but a little bit of the right ventricle sits on the diaphragm as well. Finally, the pulmonary surface, which is on the left, is mostly made up of the left ventricle.

The four valves of the heart can be auscultated at very distinct spaces, and you should make sure that you know these!
The mitral valve, which separates the left atrium from the left ventricle, can be ausculatated in the left 5th intercostal space, slightly below the nipple. This is where this patient's murmur is heard.

The tricuspid valve, which separates the right atrium from the right ventricle, can be auscultated in the 4th left intercostal space, just lateral to sternum.

The aortic valve, which separates the left ventricle from the aorta, can be ausculatated in the 2nd right intercostal space, just lateral to sternal angle.

The pulmonary valve, which separates the right ventricle from the pulmonary artery, can be auscultated in the 2nd left intercostal space, just lateral to sternal angle.

To answer this question, you need to know that the anterior interventricular artery lies in the anterior interventricular sulcus. Then, you need to identify the vein that also lies in the anterior interventricular sulcus. And that vein is the great cardiac vein. The anterior cardiac vein lies on the surface of the right atrium--it drains directly into the right atrium. The coronary sinus is located in the coronary (atrioventricular) sulcus--it is formed by the union of the great cardiac vein and the oblique vein of the left atrium, and it drains blood directly into the right atrium. The middle cardiac vein is located in the posterior interventricular sulcus--it accompanies the posterior interventricular artery. The small cardiac vein courses through the coronary sulcus with the right coronary artery.

OR just remember "too bad he died, he was a GREAT LAD" (use an irish accent)

If the object penetrated the pericardium and heart wall, the heart chamber most likely to be damaged is the right ventricle. The right ventricle is located in the lower right portion of the heart and is the chamber responsible for pumping oxygen-depleted blood to the lungs. In this case, the puncture injury would have directly affected the right ventricle, potentially causing damage to its structure and function.

The anterior interventricular artery and posterior interventricular artery travel on the anterior and posterior surfaces of the interventricular groove. These two vessels often anastamose. If there was a very extensive anastamosis between the anterior and posterior interventricular arteries, it is possible that the posterior interventricular artery might supply the tissue usually fed by the anterior interventricular artery. The other arteries listed would not be able to anastamose with anterior interventricular artery; they supply other areas of the heart.

During ventricular diastole, the heart muscles relax, and the ventricles are filled with blood from the atria. This relaxation phase allows the coronary arteries, which supply oxygenated blood to the heart muscle itself, to fill with blood and nourish the heart. Therefore, the filling of coronary arteries occurs during ventricular diastole.

The leaflets of the pulmonic valve are named anterior, left, and right, according to their orientation.
The leaflets of the aortic valve are named posterior, left, and right, with the left and right aortic sinuses above these leaflets giving off their respective coronary arteries.
The mitral valve has anterior and posterior cusps, while the tricuspid valve has septal, anterior, and smaller posterior cusps.

The right and left bundles of conduction travel in the interventricular septum. So, the artery that has been occluded must be the one that supplies the interventricular septum. The most important source of blood to the interventricular septum is the anterior interventricular artery, a branch of the left coronary artery.
Although the posterior interventricular artery partially supplies blood to the interventricular septum, it might not be enough to support the tissue in this region.

The circumflex branch of the left coronary artery provides blood to the posterior surface of the left ventricle.
The acute marginal branch of the right coronary artery provides blood to the right ventricle.

The oblique pericardial sinus is an area of the pericardial cavity located behind the left atrium of heart where the serous pericardium reflects onto the inferior vena cava and pulmonary veins. If you slide your fingers under the heart, they will be in this space. The other pericardial sinus that you should be familiar with is the transverse sinus. The transverse sinus is an area of the pericardial cavity located behind the aorta and pulmonary trunk and anterior to the superior vena cava. It separates the outflow vessels from inflow vessels.

The cardiac notch is an indentation in the superior lobe of the left lung which creates the lingula.
The costamediastinal recess is an area in the pleural sac where the costal pleura changes to the mediastinal pleura.
Finally, the hilar reflection is the reflection of pleura at the root of the lung, where visceral pleura on the lung becomes continuous with the parietal mediastinal pleura.

In these sorts of questions, you need to identify the valve immediately distal to the area of high pressure. This is the valve that must be blocked, because you can assume that blood is backing up into the area where the pressure is high. In this case, pressure is high in the right ventricle. So, there must be stenosis of the pulmonic valve, which allows blood to leave the right ventricle and travel to the lung.

If there was stenosis of the aortic valve, pressure would be high in the left ventricle. If there was stenosis of the tricuspid valve, pressure would be high in the right atrium. If there was stenosis of the mitral valve, pressure would be high in the left atrium. If you understand the path of blood flow in the heart, you can understand all these scenarios!

Ventricular diastole is the period when the ventricles relax and fill with blood. So, the AV valves need to be open at this time so that blood can flow from the atria to the ventricles. The right AV valve is called the tricuspid valve--it has three leaflets. The left AV valve is called the mitral valve and has two leaflets. Remember, the right side of the heart is pumping blood to the lungs so that it can be oxygenated. So, the blood flowing through the right AV valve will be deoxygenated, while the blood flowing through the left AV valve will be oxygenated.
Finally, remember that the chordae tendineae and the papillary muscles do not pull the AV valves open! These structures serve to prevent the valves from prolapsing during systole.

The coronary sulcus is the groove which separates the atria from the ventricles. The right and left coronary arteries, circumflex artery, and coronary sinus all lie in this groove. The right marginal artery is a branch of the right coronary artery which lies on the right ventricle and supplies that chamber of the heart

It's best to listen to sounds associated with the tricuspid valve at the fourth left intercostal space, just lateral to the sternum. The answer that comes the closest to this is E. What would you hear in the other spaces? Below the left nipple, in the fifth intercostal space, you would be auscultating the mitral valve. This is also the valve that you can hear at the apex of the heart. The right 2nd intercostal space near the sternum is the site for auscultating the aortic valve. Finally, it would be difficult to hear anything over the sternal angle, since the stethoscope would be over bone, which would blunt any sounds!

The esophagus is closely related to the posterior surface of the pericardial sac.

After coming from the heart, the aorta arches over the left pulmonary artery and left bronchus. Eventually, just above the diaphragm, this vessel is posterior to the esophagus.

The azygos vein, on the right side of the thorax, arches over the right pulmonary artery and bronchus. It is also posterior to the esophagus.
The thoracic duct is posterior to the esophagus as well and does not contact the pericardial sac.
Finally, the trachea is superior to the heart.

Below the level of the sternal angle, the thoracic duct lies posterior to the esophagus, between the azygos vein and the descending aorta. So, if the azygos vein became dilated, it could impinge on the thoracic duct. The trachea is superior to the azygos vein, which loops over the right bronchus before emptying into the superior vena cava. This means that a dilated azygos vein would have little impact on the trachea. Because the azygos is on the right side of the body, it could not compress anything at the root of the left lung. The right phrenic nerve is anterior to the azygos vein. The descending aorta is much larger and more muscular than the azygos vein, so it is unlikely that it would be compressed by this much smaller structure.

When fluid accumulates in the pericardial sac, it is necessary to remove that fluid by performing a pericardiocentesis. A needle is inserted just to the left of the xiphisternal junction, and the needle passes superiorly to enter the pericardial sac. Then, the fluid can be aspirated into the needle.

The correct answer is Pulmonary. The pulmonary valve is located between the right ventricle and the pulmonary artery. It has three leaflets, which are described as anterior, left, and right. These leaflets open and close to allow blood to flow from the right ventricle to the pulmonary artery and prevent backflow.

The ligamentum arteriosum is the point where the left pulmonary artery connects with the undersurface of aortic arch. It is a remnant of the fetal ductus arteriosus, which shunted blood away from the developing lungs. Because the aorta is tethered to the pulmonary artery by the ligamentum arteriosum, the part of the aorta near the ligamentum is vulnerable to damage in a traumatic acceleration/deceleration injury - it could pull away and tear. The other answer choices do not describe points of the aorta where a mobile and fixed portion meet. Therefore, these parts of the aorta would not be vulnerable to this type of traumatic injury.

When a nerve fiber reaches the sympathetic chain, there are three things that can happen. First, the nerve fibers can enter a ganglia, synapse at that level, and rejoin the spinal nerve via the grey ramus communicans. Second, the preganglionic nerve fibers can travel up or down the trunk, synapse in a ganglia at another level, and then rejoin a spinal nerve. This is how sympathetic fibers join spinal nerves at the cervical and lumbar levels, which are above and below the lateral horn. Third, some preganglionic fibers do not synapse in the trunk and, instead, form splanchnic nerves. These nerves descend into the abdomen and synapse in other ganglia.

The greater thoracic splanchnic nerve contains preganglionic fibers that are destined to synapse in the celiac plexus. The recurrent laryngeal nerve provides motor and sensory innervation to the upper esophagus and pharynx. Finally, the vagus nerve is a mixed nerve that carries preganglionic parasympathetic fibers. None of these nerves carry postganglionic sympathetic fibers.

The ulnar nerve innervates muscles of the hand, arm, and provides some sensory innervation to skin of the hand and arm. It is derived from ventral rami of spinal nerves, all of which carry postganglionic sympathetic fibers (for vascular smooth muscle, arrector pili muscles, and sweat glands).