Lecture 2.2 - Heart and Mediastinum Flashcards
Where is the heart oriented in the thorax?
- mostly on left
- apex pointed anterior-inferiorly
- right surface is mostly right atrium
- anterior surface is mostly right ventricle
- left surface is mostly left ventricle
What are the 4 layers of the heart?
- Fibrous pericardium
- Serous pericardium: a continuous membrane that forms two layers separated by a serous-filled pericardial cavity
- parietal pericardium: adhered to deep surface of fibrous pericardium
- visceral pericardium (epicardium): outer layer of heart tissue - Myocardium: thick made layer of specialized cardiac muscle
- Endocardium: thin internal lining membrane of the heart that also lines the valves
What are the atria?
- atria are the receiving chambers that pump blood into the ventricles
How does blood flow through the right ventricle?
- pumps blood through the pulmonary valve into the pulmonary trunk (artery)
- pulmonary arteries carry low oxygen blood to the lungs
Blood flow in left atrium?
- 4 pulmonary veins receive well oxygenated blood from the lungs
- auricle projects anteriorly
- pectinate muscles
- foramen ovale
- blood leaves through mitral valve to left ventricle
What are the components of the left ventricle?
- mitral (bicuspid) valve
- chordae tendineae
- papillary muscles (2)
- trabeculae carneae
- pumps blood through aortic semilunar valve in aortic arch
- very thick walls
Name the 4 heart valves
- tricuspid valve
- pulmonary valve
- mitral valve
- aortic valve
What are the atrioventricular valves? What are their purposes? How are chordae tendinae and papillary muscles involved?
- Tricuspid valve: prevents backflow through right atrioventricular orifice
- Mitral (bicuspid) valve: prevents backflow through left atrioventricular orifice
- Chordae tendineae and papillary muscles prevent cusps from inverting back into the atria due to pressure of blood ventricles
What are the semilunar valves and their actions?
- Pulmonary valve: prevents blood from backflowing from pulmonary artery into right ventricle
- Aortic valve: prevents blood from backflowing from aorta into left ventricle
- Each has 3 cusps, which create 3 sinuses that fill when valve close
What are coronary arteries? What is the difference between left and right?
- supply epicardium and myocardium
- 1st branch of aorta
- arises from aortic sinuses
1. Left coronary artery: - lies in left atrioventricular groove
- its branches supply: left atrium, most of left ventricle, and part of right ventricle.
2. Right coronary artery: - lies in right atrioventricular groove
- its branches supply: right atrium, most of right ventricle, and part of left ventricle
What is heart dominance and its percentages?
- whichever coronary artery leads to the posterior interventricular artery
- 70% right dominant
- 10% left dominant
- 20% co dominant
What are the cardiac veins? Where are they located? Where do they drain?
- most cardiac veins drain into coronary sinus, lying in the left atrioventricular groove and coronary sinus then drains into right atrium.
1. Anterior: lie across right atrioventricular groove and empties directly into right atrium.
2. Great: lies in anterior interventricular groove with anterior interventricular artery
3. Small: lies along right margin with right marginal artery then in right atrioventricular groove with right coronary artery
4. Middle: lies in posterior interventricular groove with posterior interventricular artery
What is the Mediastinum? Where is it located and what does it do?
- interpulmonary space (the area between the pulmonary cavities)
- contains all the thoracic viscera and structures except for the lungs
- extends from superior thoracic aperture to the diaphragm, and from the sternum to the thoracic vertebrae (4 divisions)
- superior, anterior, middle, and posterior mediastinum
Where is the anterior mediastinum and what does it contain?
- between body of sternum and pericardium
- contains remnants of thymus, internal thoracic artery and branches, lymph nodes, fat, connective tissue
Where is the middle mediastinum and what does it contain?
- between right and left pleural cavities
- contains pericardium, heart, ascending aorta, pulmonary trunk and arteries, pulmonary veins, end of superior vena cava, arch of azygos vein, primary bronchi, phrenic nerve
Where is the superior mediastinum and what does it contain?
- from superior thoracic aperture to transverse thoracic plane (sternal angle to T4/5)
- contains: brachiocephalic veins, superior vena cava, arch of aorta and branches (ABCS), trachea, esophagus, thoracic duct, thymus, vagus nerve, left recurrent laryngeal nerve, phrenic nerve
Where is the posterior mediastinum and what does it contain?
- between pericardium and T4-T12 vertebra
- contains esophagus, descending thoracic aorta, thoracic duct, azygos and hemiazygos weins, vagus nerves, sympathetic trunk
What are the veins of thorax?
brachiocephalic, superior vena cava (from upper body), azygos vein (drains right thorax), inferior vena cava (from lower body), and hemiazygos vein (drains left thorax)
What does the lymphatic system do? What are the major lymph vessels and where do they drain?
- returns excess tissue fluid (lymph) to the bloodstream
- lymph nodes filter foreign materials, trigger immune system
- major lymph vessels:
- thoracic duct drains 3/4 of body, empties into left subclavian vein
- right lymphatic duct drains upper right quadrant, empties into right subclavian vein
What is the fossa ovalis?
a remnant of a fetal valve in atrial septum which shunted blood from the right atrium to left atrium, bypassing the non functioning lungs.
What aligns with the pectinate muscles?
- the auricle and anterior part of atrium are lined with pectinate muscles
What kind of blood does the R atrium receive and from where? Where does the blood pass through?
- receives poorly oxygenated blood from body: superior/inferior vena cava and coronary sinus
- blood passes through tricuspid valve into the right ventricle
