THE HEART THE HEART MEDIASTINUM PERICARDIUM HEART THE HEART THE - PowerPoint PPT Presentation

THE HEART

THE HEART • MEDIASTINUM • PERICARDIUM • HEART

THE HEART THE MEDIASTINUM The medias5num occupied by the mass of 2ssue between the two pulmonary cavi2es, is the central compartment of the thoracic cavity. The medias2num is an interpleural space and consists of the superior medias2num and inferior medias2num, which divides into the anterior , middle , and posterior medias2na.

THE HEART THE SUPERIOR MEDIASTINUM The superior medias5num contains the SVC, brachiocephalic veins, arch of the aorta, thoracic duct, trachea, esophagus, thymus, vagus, leB recurrent laryngeal, and phrenic nerves. The superior vena cava (SVC) returns blood from all structures superior to the diaphragm, except the lungs and heart. The arch of the aorta (aor5c arch) , the curved con2nua2on of the ascending aorta. The arch of the azygos vein occupies a posi2on corresponding to the aorta on the right side of the trachea over the root of the right lung, although the blood is flowing in the opposite direc2on. The ligamentum arteriosum , the remnant of the fetal ductus arteriosus, passes from the root of the leB pulmonary artery to the inferior surface of the arch of the aorta. The brachiocephalic trunk , the first and largest branch of the arch of the aorta, arises posterior to the manubrium, where it is anterior to the trachea and posterior to the leB brachiocephalic vein.

THE HEART THE SUPERIOR MEDIASTINUM The leJ common caro5d artery , the second branch of the arch of the aorta, arises posterior to the manubrium, slightly posterior and to the leB of the brachiocephalic trunk. The leJ subclavian artery , the third branch of the arch of the aorta, arises from the posterior part of the arch, just posterior to the leB common caro2d artery. The right vagus nerve (RVN) enters the thorax anterior to the right subclavian artery, where it gives rise to the right recurrent laryngeal nerve. The leJ vagus nerve (LVN) descends in the neck posterior to the leB common caro2d artery

THE HEART THE SUPERIOR MEDIASTINUM The leJ vagus nerve (LVN) is separated laterally from the phrenic nerve by the leB superior intercostal vein. As the LVN curves medially at the inferior border of the arch of the aorta, it gives off the leJ recurrent laryngeal nerve . The leB recurrent laryngeal nerve passes inferior to the arch of the aorta, immediately lateral to the ligamentum arteriosum, and ascends to the larynx in the groove between the trachea and the esophagus .

THE HEART THE ANTERIOR MEDIASTINUM The anterior medias5num contains the remnants of the thymus gland, lymph nodes, and fat.

THE HEART THE MIDDLE MEDIASTINUM The middle medias5num contains the • heart, • pericardium, • phrenic nerves, • roots of the great vessels, • arch of the azygos vein, and • main bronchi.

THE HEART THE POSTERIOR MEDIASTINUM The posterior medias5num contains the • esophagus, • thoracic aorta, • azygos and hemiazygos veins, • thoracic duct, • vagus nerves, • sympathe2c trunks, • splanchnic nerves.

THE HEART THE PERICARDIUM The middle medias5num includes the pericardium , heart , and roots of its great vessels : • ascending aorta, • pulmonary trunk, • SVC. The pericardium is a fibroserous membrane that covers: • the heart and • the beginning of its great vessels. The tough external layer, the fibrous pericardium , is con2nuous with the central tendon of the diaphragm.

THE HEART THE PERICARDIUM The internal surface of the fibrous pericardium is lined with a glistening serous membrane, the parietal layer of serous pericardium . The parietal layer of serous pericardium is reflected onto the heart at the great vessels (aorta, pulmonary trunk and veins, and superior and inferior venae cavae) as the visceral layer of serous pericardium .

THE HEART THE PERICARDIUM The fibrous pericardium is: • con2nuous superiorly with the tunica adven55a of the great vessels entering and leaving the heart and with the pretracheal layer of deep cervical fascia. • aOached anteriorly to the posterior surface of the sternum by the sternopericardial ligaments , which are highly variable in their development. • bound posteriorly by loose connec2ve 2ssue to structures in the posterior medias2num. • con2nuous inferiorly with the central tendon of the diaphragm

THE HEART THE PERICARDIUM The inferior wall (floor) of the fibrous pericardial sac is firmly aOached and confluent (par2ally blended) centrally with the central tendon of the diaphragm - the pericardiacophrenic ligament . The pericardium is influenced by movements of the heart and great vessels, the sternum, and the diaphragm.

THE HEART THE PERICARDIUM The pericardial cavity is the poten5al space between opposing layers of the parietal and visceral layers of serous pericardium. It normally contains a thin film of fluid that enables the heart to move and beat in a fric2onless environment. The visceral layer of serous pericardium forms the epicardium , the outermost of three layers of the heart wall. The transverse pericardial sinus is a transversely running passage within the pericardial cavity between these two groups of vessels and the reflec2ons of serous pericardium around them.

THE HEART THE PERICARDIUM A pericardial reflec2on surrounding the veins of the heart forms the oblique pericardial sinus , a wide pocket-like recess in the pericardial cavity posterior to the base (posterior aspect) of the heart, formed by the leJ atrium The arterial supply of the pericardium is mainly from a slender branch of the internal thoracic artery, the pericardiacophrenic artery .

THE HEART THE PERICARDIUM The nerve supply of the pericardium is from the: • Phrenic nerves (C3–C5), primary source of sensory fibers; pain sensa2ons conveyed by these nerves are commonly referred to the skin (C3–C5 dermatomes) of the ipsilateral supraclavicular region ( top of the shoulder of the same side ). • Vagus nerves , func2on uncertain. • Sympathe5c trunks , vasomotor.

THE HEART THE PERICARDIUM The Func5on of the Pericardium: • Protects and anchors the heart • Prevents overfilling of the heart with blood • Allows for the heart to work in a rela2vely fric2on-free environment

THE HEART THE HEART • Center of the cardiovascular system, the heart. • Connects to blood vessels that transport blood between the heart and other body 2ssues. arteries carry blood away from the heart • veins carry blood back to the heart • • Arteries carry blood high in oxygen. (except for the pulmonary arteries) • • Veins carry blood low in oxygen. (except for the pulmonary veins) • • Arteries and veins entering and leaving the heart are called the great vessels

THE HEART THE HEART • Ensures the unidirec5onal flow of blood through both the heart and the blood vessels. • Backflow of blood is prevented by valves within the heart. • Acts like two independent , side-by-side pumps that work independently but at the same rate . (double circuit) • one directs blood to the lungs for gas exchange • the other directs blood to body 5ssues for nutrient delivery

THE HEART THE HEART Vessels returning blood to the heart include: 1. Superior and inferior venae cavae 2. Right and leB pulmonary veins

THE HEART THE HEART Vessels conveying blood away from the heart include: 1. Pulmonary trunk, which splits into right and leB pulmonary arteries 2. Ascending aorta (three branches) – a. Brachiocephalic b. LeB common caro2d c. Subclavian arteries

THE HEART THE HEART Vessels returning blood to the heart include: 1. Superior and inferior venae cavae 2. Right and leB pulmonary veins Vessels conveying blood away from the heart include: 1. Pulmonary trunk, which splits into right and leB pulmonary arteries 2. Ascending aorta (three branches) – a. Brachiocephalic b. LeB common caro2d c. Subclavian arteries

THE HEART ATRIA OF THE HEART • Atria are the receiving chambers of the heart • Each atrium has a protruding auricle • Pec5nate muscles located within the anterior wall of the right atrium • Blood enters right atria from superior and inferior venae cavae and coronary sinus • Blood enters leJ atria from pulmonary veins

THE HEART VENTRICULES OF THE HEART • Ventricles are the discharging chambers of the heart • Papillary muscles and trabeculae carneae muscles mark ventricular walls • Right ventricle pumps blood into the pulmonary trunk • LeJ ventricle pumps blood into the aorta • Myocardium of leJ ventricle is much thicker than the right.

THE HEART • Right atrium à tricuspid valve à right ventricle • Right ventricle à pulmonary PATHWAY OF BLOOD semilunar valve à pulmonary arteries à lungs THROUGH THE HEART • Lungs à pulmonary veins à leB atrium AND LUNGS • LeB atrium à bicuspid valve à leB ventricle • LeB ventricle à aor5c semilunar valve à aorta • Aorta à systemic circula2on

THE HEART THE HEART The right side of the heart (right heart) receives poorly oxygenated (venous) blood from the body through the SVC and IVC and pumps it through the pulmonary trunk and arteries to the lungs for oxygena2on. The leJ side of the heart (leJ heart) receives well-oxygenated (arterial) blood from the lungs through the pulmonary veins and pumps it into the aorta for distribu2on to the body.