Anatomy of circulation II_ conduction system and peripheral vessels_ part 2.pdf

13/03/24 Anatomy of circulation II: conduction system and peripheral vessels: part 2 Learning objective: de ne all of the great vessels and their functions, including what joins to make them and what they are carrying. Explain which vessels are anterior and what are posterior. Great vessels: These a...

13/03/24 Anatomy of circulation II: conduction system and peripheral vessels: part 2 Learning objective: de ne all of the great vessels and their functions, including what joins to make them and what they are carrying. Explain which vessels are anterior and what are posterior. Great vessels: These are the arteries and veins connected directly to the heart: Aorta. Pulmonary arteries. Pulmonary veins. SVC. IVC. Aorta: The thoracic portion of the aorta can be divided into 3 parts: 1. Ascending aorta. 2. Arch of the aorta. 3. Descending aorta. Ascending Aorta: Transports oxygenated blood from the left ventricle to the body. It is contained within the pericardial sac. Begins at the aortic ori ce of the left ventricle. Then it ascends and moves to the right. At the level of the sternal plane, it enters the superior mediastinum and is known as the arch of the aorta. There are 2 branches of the ascending aorta: the left and right coronary arteries. Arch of the Aorta: Continuation of the ascending aorta within the superior mediastinum. Archer posteriorly and to the left. There are 3 branches: ligamentum arteriosum 1. Brachiocephalic trunk. 2. Left common carotid artery. 3. Left subclavian artery. There is a ligamentum arteriosum which is a remnant of the ductus arteriosus. Descending Aorta: Continuation of the arch of the aorta at the sternal plane. Descend the thorax in the posterior mediastinum. It begins to the left of the vertebral bodies and as it descends, it moves anterior to the vertebral bodies. It terminates by passing through the aortic hiatus of the diaphragm at T12. Pulmonary Trunk: Transports venous blood from the right ventricle to the lungs. Begins as the most anterior of the great vessels. As it ascends, it moves posteriorly and to the left of the ascending aorta. The pulmonary trunk bifurcates into the left and right pulmonary arteries ( at T5 ). Left pulmonary artery goes to left lung. Pulmonary Veins: Transport oxygenated blood from the lungs to the left atrium. There are 4 pulmonary veins: 1. Left superior pulmonary vein. 2. Right superior pulmonary vein. 3. Left inferior pulmonary vein. 4. Right inferior pulmonary vein. Vena Cava: SVC: The SVC returns blood from all structures superior to the diaphragm, except for the heart and lungs. For example, transports venous blood from the head, the neck, the upper limbs and the intercostal veins. It is formed by the union of the left and right brachiocephalic veins. The right brachiocephalic vein is formed by the union of the right subclavian and right internal jugular veins. The same for the left side. Begins posterior to the 1st right coastal cartilage and descends until the 3rd coastal cartilage. Drains into the right atrium. terminates here then into RA drains It is valveless, this is because the blood ow is in the direction of gravity so valves are not needed. IVC: Transports venous blood from the abdomen, pelvis and lower limbs. Passes through the central tendon at T8. Thoracic portion is very short and passes through the pericardium. It drains into the inferior aspect of the right atrium. It is valveless; the for ward ow of blood to the heart is driven by the differential pressure created by normal respiration.