CVS L5 (1) PDF - Cardiovascular System Lecture 5

Cardiovascular system lecture 5 Mo Anatomy  CVS ANATOMY Mediastinum Mediastinum Definition  The median partition between the two pleural cavities. ...

Cardiovascular system lecture 5 Mo Anatomy  CVS ANATOMY Mediastinum Mediastinum Definition  The median partition between the two pleural cavities.  Extends from the sternum anteriorly to the vertebral column posteriorly. Position  Extends from the thoracic inlet above to the diaphragm below.  The mediastinum is divided by an imaginary plane drawn from the sternal angle to the disc between the 4th & 5th thoracic vertebrae into: a) Superior mediastinum. Divisions b) Inferior mediastinum, which is further divided into:  Anterior mediastinum.  Middle mediastinum.  Posterior mediastinum. DR. ME Page | 1 CVS ANATOMY Mediastinum Boundaries Superior Mediastinum Anterior Mediastinum Posterior Mediastinum Imaginary plane extending from the sternal angle to the disc Superiorly Thoracic inlet, 1st rib ---------------- between the 4th & 5th thoracic vertebrae Imaginary plane extending from the sternal angle to Inferiorly --------------- Diaphragm the disc between the 4th & 5th thoracic vertebrae Pericardium above & diaphragm Anteriorly Manubrium sterni Body of the sternum below Upper four thoracic Lower eight thoracic Posteriorly Pericardium vertebrae vertebrae Mediastinal layer of the On Each Parietal pleura ----------------- Side parietal pleura DR. ME Page | 2 CVS ANATOMY Mediastinum Content of Superior Mediastinum  Lower part:  Arch of the aorta (lies behind the lower half of manubrium sterni)  Upper part: Brachiocephalic, left common carotid, and left subclavian arteries Arteries Nb  Brachiocephalic artery ascends on the right side of the trachea.  Left common carotid and left subclavian arteries ascend on the left side of the trachea. 1) Right brachiocephalic (innominate) vein descends on the right side of the brachiocephalic artery. 2) Left brachiocephalic (innominate) vein passes obliquely along the upper Veins border of the arch of the aorta. 3) Upper half of the superior vena cava (SVC) descends in line with the right brachiocephalic vein. 2 Vagi nerves: 1) Right vagus: descends on the right side of the trachea. 2) Left vagus: descends between the left common carotid and left subclavian vein, then on the left side of the arch of the aorta. Nerves Phrenic nerves: 1) Right phrenic nerve: descends on the right side of the right brachiocephalic and the superior vena cava. 2) Left phrenic nerve: descends on the left side of the left common carotid artery, then on the left side of the arch of the aorta. DR. ME Page | 3 CVS ANATOMY Mediastinum Left recurrent laryngeal nerve:  arises from the left vagus and curves below the arch of the aorta, then ascends between the trachea and esophagus. Cardiac branches:  arise from the two vagi, the left recurrent laryngeal nerve, and the two sympathetic trunks. a) Trachea: Lies in the midline posterior to the major vessels and in front of the esophagus. Tubes b) Esophagus: Most posterior structure in the superior mediastinum, lying behind the trachea and in front of the vertebral column. c) Thoracic duct: Ascends behind the left border of the esophagus.  Brachiocephalic group. Lymph  Paratracheal group. Nodes  Superior tracheobronchial group. Thymus  Lies in contact with the inner surface of the manubrium sterni. Gland DR. ME Page | 4 CVS ANATOMY Mediastinum Content of Inferior Mediastinum Anterior Mediastinum Middle Mediastinum Posterior Mediastinum 1) Superior & inferior 1) Heart & pericardium. 1) Descending thoracic aorta & posterior sternopericardial ligaments. 2) Ascending aorta. intercostal arteries. 2) Part of the thymus gland. 3) Pulmonary trunk: to the left of the ascending 2) Azygos & hemiazygos veins & posterior 3) Two to three lymph nodes. aorta. intercostal veins. 4) Areolar tissue. 4) Right & left pulmonary arteries. 3) Esophagus: on the right side of the aorta, then 5) Four pulmonary veins. crosses in front of its lower part. 6) Lower half of the superior vena cava: to the right 4) Two vagi nerves forming the esophageal plexus. Contents of the ascending aorta. 5) Splanchnic nerves (greater, lesser & lowest) 7) Uppermost part of the inferior vena cava. arising from the sympathetic trunk. 8) Bifurcation of the trachea, right & left principal 6) Thoracic duct: ascends on the right side of the bronchi: below aortic arch. esophagus. 9) Right & left phrenic nerves & pericardiophrenic 7) Posterior mediastinal lymph nodes. vessels: along the sides of the pericardium. 10) Inferior tracheobronchial lymph nodes: below the bifurcation of the trachea. Thymus gland is present in both Esophagus, two vagi nerves, and thoracic duct are Superior vena cava & phrenic nerves are present in Notes the superior and anterior present in both the superior and posterior both the superior and middle mediastinum. mediastinum. mediastinum. DR. ME Page | 5 CVS ANATOMY Mediastinum Anterior Mediastinum Middle Mediastinum Posterior Mediastinum DR. ME Page | 6