CV Anatomy Flashcards
What is the pericardium made up of?
The pericardium is a fibroserous sac surrounding the heart and the roots of the great vessels. It consists of two components, the fibrous pericardium and the serous pericardium.
The fibrous pericardium is a tough connective tissue outer layer that defines the boundaries of the middle mediastinum.
The serous pericardium is thin and consists of two parts:
▪ The parietal layer of serous pericardium lines the inner surface of the fibrous pericardium.
▪ The visceral layer ( epicardium ) of serous pericardium adheres to the heart and forms its outer covering.
The narrow space created between the two layers of serous pericardium, containing a small amount of fluid, is the pericardial cavity . This potential space allows for the relatively uninhibited movement of the heart.
Fibrous Pericardium
Cone shaped bag- base on the diaphragm attached by central tendon of the diaphragm to small muscular part of diaphragm, apex continuous with the adventitia (outer layer of connective tissue) of the great vessels.
The phrenic nerves originate from spinal cord levels c3 and c5 pass through the fibrous pericardium
Pericardiacophrenic vessels are also located within and supply the fibrous pericardium as they pass through the thoracic cavity
Serous Pericardium
The parietal layer of serous pericardium is continuous with the visceral layer of serous pericardium around the roots of the great vessels. These reflections of serous pericardium ( Fig. 3.61 ) occur in two locations:
▪ one superiorly, surrounding the arteries—the aorta and the pulmonary trunk;
▪ the second more posteriorly, surrounding the veins—the superior and inferior vena cava and the pulmonary veins.
What supplies the pericardium?
The pericardium is supplied by branches from the internal thoracic, pericardiacophrenic, musculophrenic, and superior phrenic arteries, and the thoracic aorta.
Veins from the pericardium enter the azygos system of veins and the internal thoracic and superior phrenic veins.
Nerves supplying the pericardium arise from the vagus nerve [X], the sympathetic trunks, and the phrenic nerves.
What is pericarditis?
Pericarditis is an inflammatory condition of the pericardium. Common causes are viral and bacterial infections, systemic illnesses (e.g., chronic renal failure), and after myocardial infarction.
Pericarditis must be distinguished from myocardial infarction because the treatment and prognosis are quite different. As in patients with myocardial infarction, patients with pericarditis complain of continuous central chest pain that may radiate to one or both arms. Unlike myocardial infarction, however, the pain from pericarditis may be relieved by sitting forward. An electrocardiogram (ECG) is used to help differentiate between the two conditions. It usually shows diffuse ST elevation. Echocardiography can also be performed if there is clinical or radiographic suspicion of pericardial effusion.
What is pericardial effusion?
Normally, only a tiny amount of fluid is present between the visceral and parietal layers of the serous pericardium. In certain situations, this space can be filled with excess fluid (pericardial effusion)
Because the fibrous pericardium is a “relatively fixed” structure that cannot expand easily, a rapid accumulation of excess fluid within the pericardial sac compresses the heart (cardiac tamponade), resulting in biventricular failure. Removing the fluid with a needle inserted into the pericardial sac can relieve the symptoms.
What is Constrictive pericarditis
Abnormal thickening of the pericardial sac (constrictive pericarditis), which usually involves only the parietal pericardium, but can also less frequently involve the visceral layer, can compress the heart, impairing heart function and resulting in heart failure. It can present acutely but often results in a chronic condition when thickened pericardium with fibrin deposits causes pericardial inflammation, leading to chronic scarring and pericardial calcification. As a result, normal filling during the diastolic phase of the cardiac cycle is severely restricted. The diagnosis is made by inspecting the jugular venous pulse in the neck. In normal individuals, the jugular venous pulse drops on inspiration. In patients with constrictive pericarditis, the reverse happens and this is called Kussmaul’s sign. Treatment often involves surgical opening of the pericardial sac.
What does the base of the heart consist of?
The base of the heart is quadrilateral and directed posteriorly. It consists of:
▪ the left atrium,
▪ a small portion of the right atrium, and
▪ the proximal parts of the great veins (superior and inferior venae cavae and the pulmonary veins)
The base of the heart is fixed posteriorly to the pericardial wall
The oesophagus lies immediately posterior to the base
Describe the coronary sulcus.
The coronary sulcus circles the heart, separating the atria from the ventricles. As it circles the heart, it contains the right coronary artery, the small cardiac vein, the coronary sinus, and the circumflex branch of the left coronary artery.
What 3 vessels return blood to the right atrium?
▪ the superior and inferior venae cavae, which together deliver blood to the heart from the body; and
▪ the coronary sinus, which returns blood from the walls of the heart itself.
The superior vena cava enters the upper posterior portion of the right atrium, and the inferior vena cava and coronary sinus enter the lower posterior portion of the right atrium.
What separates the right atrium from the left atrium?
nteratrial septum , which faces forward and to the right because the left atrium lies posteriorly and to the left of the right atrium.
Name and describe the three papillary muscles in the right ventricle.
▪ The anterior papillary muscle is the largest and most constant papillary muscle, and arises from the anterior wall of the ventricle.
▪ The posterior papillary muscle may consist of one, two, or three structures, with some chordae tendineae arising directly from the ventricular wall.
▪ The septal papillary muscle is the most inconsistent papillary muscle, being either small or absent, with chordae tendineae emerging directly from the septal wall.
What is the role of the papillary muscles and associated chordate tendinae?
Keep the tricuspid and bicuspid (mitral) av valve closed during the dramatic changes in ventricular size that occur during contraction.
Contraction of the papillary muscles attached to the cusps by chordae tendineae prevents the cusps from being everted into the right and left atrium.
Where does the right coronary artery supply to?
The right coronary artery originates from the right aortic sinus of the ascending aorta and supplies the:
right atrium and right ventricle,
the sinu-atrial and atrioventricular nodes,
the interatrial septum,
a portion of the left atrium,
the posteroinferior one third of the interventricular septum, and a portion of the posterior part of the left ventricle.
Where does the left coronary artery supply to?
The left coronary artery originates from the left aortic sinus of the ascending aorta. It passes between the pulmonary trunk and the left auricle before entering the coronary sulcus. Emerging from behind the pulmonary trunk, the artery divides into its two terminal branches, the anterior interventricular and the circumflex.
The distribution pattern of the left coronary artery enables it to supply most of the left atrium and left ventricle, and most of the interventricular septum, including the atrioventricular bundle and its branches.
Name the four main cardiac veins involved in venous drainage and the so additional groups of cardiac veins:
The great, middle, small, and posterior cardiac veins.
The anterior veins of the right ventricle (anterior cardiac veins)
Venae cordis minimae or veins of Thebesius
The coronary lymphatic vessels of the heart follow the coronary arteries and drain mainly into:
▪ brachiocephalic nodes, anterior to the brachiocephalic veins; and
▪ tracheobronchial nodes, at the inferior end of the trachea.
The conduction system consists of nodes and networks of specialized cardiac muscle cells organized into what four basic components?
▪ the sinu-atrial node,
▪ the atrioventricular node,
▪ the atrioventricular bundle with its right and left bundle branches, and
▪ the subendocardial plexus of conduction cells (the Purkinje fibers).
What is the role and where is the sinu - atrial node located?
Impulses start here (cardiac pacemaker)
This collection of cells is located at the superior end of the crista terminalis at the junction of the superior vena cava and the right atrium
What is the role and where is the atrioventricular node located?
Concurrently, the wave of excitation in the atria stimulates the atrioventricular node , which is located near the opening of the coronary sinus, close to the attachment of the septal cusp of the tricuspid valve, and within the atrioventricular septum.
The atrioventricular node is a collection of specialized cells that forms the beginning of an elaborate system of conducting tissue, the atrioventricular bundle, which extends the excitatory impulse to all ventricular musculature.
What is the role and where is the atrioventricular bundle located?
The atrioventricular bundle is a direct continuation of the atrioventricular node. It follows along the lower border of the membranous part of the interventricular septum before splitting into right and left bundles.
The right and left bundle branch continue on the right/left side of the interventricular septum towards the apex of the right/left ventricle. Along its course it gives off branches that eventually become continuous with the subendocardial plexus of conduction cells ( Purkinje fibers ).
Describe parasympathetic innervation:
Stimulation of the parasympathetic system:
▪ decreases heart rate,
▪ reduces force of contraction, and
▪ constricts the coronary arteries.
The preganglionic parasympathetic fibers reach the heart as cardiac branches from the right and left vagus nerves. They enter the cardiac plexus and synapse in ganglia located either within the plexus or in the walls of the atria.
