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the Cardiovascular System “Mediastinum”. By: Dr. Nabil A Khouri MD, MsC, Ph.D. Bony Thorax (Thoracic Cage). General Structure of thoracic Vertebrae. Thoracic Vertebrae. Mediastinum.
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the Cardiovascular System “Mediastinum” By:Dr. Nabil A Khouri MD, MsC, Ph.D
Mediastinum • Is the middle compartment of the thoracic cavity which is situated between the right and left mediastinal surface of the lungs covered by pleura. • Boundaries: • Anteriorly, the sternum and the costal cartilages. • Posteriorly, the bodies of 4-12 thoracic vertebrae. • Superiorly, the thoracic inlet. • Inferiorly, the diaphragm. • Laterally (on each side), the mediastinal pleura
First rib “Thoracic inlet” MEDIASTINUM Inferior mediastium Superior boundaries: Sternal Angle to T4/5 (Inter VD) Inferior boundaries: Middle of Xiphoid process to T9 Diaphragm IX
2 3 4 5 6 7 8 Body 9
The superior mediastinum Located above the heart and therefore lying behind the manubrium sterni contains: the great vessels of the heart Level of Manb. Sterni
Contents of sup. mediastinum • The arch of the aorta with its three large branches. • Right and left brachiocephalic veins. • The upper part of the superior vena cava. • The vagus (10th cranial), the phrenic and the left recurrent laryngeal nerves. • The thymus (in children, or some possible remnants in adults). • The trachea. • The esophagus. • Some lymph nodes.
A transverse section of the thorax, showing the contents of the Anterior, middle and the posterior mediastinum Posterior Mediastiunum
Content of the posterior mediastinum • artery • thoracic part of the descending aorta • veins • azygos vein • the hemiazygos vein and the accessory hemiazygos vein • nerves • vagus nerve • splanchnic nerves (but not the sympathetic chain[1]) • esophagus • thoracic duct • some lymph glands
Sympathetic plexus Br. Ceph. Vein Rt Phrenic N Intercostal arteries and veins Azygos Vein Rt. Prim. Bronch. Lymph Nods Pulmonary Arteris Pulmonary Veins Esophagus Rt. Vagus N Posterior Right side mediastinum SVC
Left Side Thoracic Cavity 1 2 3 Aorta 4 – Brachio-Ceph. Trunk 5 - Descending Aorta 6 - Left. Main Bronch. 7 - Pulmonary V 8 - Phrinic N and Pericardio-phrenic A
Right Left
The Pericardium • Outer sac – Fibrous • Inner - Serous, is a double layered sac –(parietal and visceral pericardium • Between the parietal and visceral pericardium is aSmall space – the pericardialCavity • It is filled with pericardial fluid (lubricates and reduces friction between the two surfaces). • The most inner of these two serous layers actually forms the Epicardium and is in direct contact with myocardium
The Pericardium Filled with Pericardial Fluid Pericardio-phrenic Ligament Central tendon of the diaphragm
Superior Vena Cava Aorta Pulmonary trunk Pulmonary Arteries Inferior Vena Cava Right Left Pericardial sinuses
Pericardial Sinuses • Two In number: • Lies within the pericardial cavity, at the points where the visceral and parietal pericardia are continuous with one another. • The pericardial sinuses are: • transverse pericardial sinus (Open “Connected Lt-Rt”) • Between the reflections of pericardium onto the aorta and pulmonary trunk superiorly and the pulmonary veins inferiorly • oblique pericardial sinus (closed “Not continuous”) • The cul-de-sac enclosed located between the limbs of the U lies behind the left atrium and is known as the oblique sinus, • It is a recess in the pericardial cavityposterior to the base of the heart bounded laterally by the pericardialreflections on the pulmonary veins and inferior vena cava, and posteriorly by the pericardium overlying the anterioraspect of the oesophagus.
THE Pericardial reflection Right side view Oblique Sinus
Innervations • The fibrous pericardium and the parietal layer of the serous pericardium are sensory innervated by the phrenic nerves (C3-C5). • The epicardium receives autonomic innervation from the underlying heart. • Excessive accumulation of fluid in the pericardial cavity and may lead to the compression of the heart. • Restriction of the heart movement may lead to cardiac arrest.