2Defination:- It is a space between the two pleural cavities. It is the central compartment of the thoracic cavity.It contains all the thoracic viscera and structures except the lungs.It is bounded anteriorly by the sternum,posteriorly by the thoracic vertebrae.
4DIVISIONS OF MEDIASTINUM It is divided by an immaginary plane passing through the sternal angle anteriorly and posteriorly by the intervertebral discs between T4 &T5.This plane is called transverse thoracic plane.Superior mediastinum lies above this plane.Inferior mediastinum lies below this plane.
5INFERIOR MEDIASTINUMDue to the presence of pericardium and heart it is further divided into:-Anterior mediastinum,infront of heartMiddle mediastinum,pericardium &heart.Posterior mediastinum, behind the heart.
6DIVISION OF MEDIASTINUM Superior mediastinum,Middle mediastinum,Anterior mediastinum,Posterior mediastinum.
7Structures in the mediastinum Thymus gland in children (anterior)Pericardial sack,heart,vessels(middle)Esophagus,aorta,thoracic duct,azygos vein(posterior)Trachea, great vessels(superior)
8SUPERIOR MEDIASTINUM It lies above the transverse thoracic plane. It contains aortic arches, thymus, terminal part of S.V.C.,brachiocephalic veins,Trachea and esophagus.
16APPLIED ANATOMYTumours arising from thymus,Thymoma compresses the mediastinum.Pancoast tumour may compress the sympathetic ganglion and cause Horner’s syndrome.Pericardial effusion-cardiac tamponade due to pericardial effusion.Hilar group of lymph nodes enlargment leads to dysphagia and dyspnoea.Compression over recurrent laryngeal nerves lead to hoarseness of voice.
20PERICARDIUM Peri= around Cardium= heart It is a fibro-serous sac which surround theHeart and the rootsof the large vesselsIt consist of:1- The fibrous pericardium2-The serous pericardiumtwo layer:parietal layerVisceral layer3- the sinuses of the pericardium(transverse – oblique )
21FIBROUS &SEROUS PERICARDIUM Fibrous pericardium is made up of dense conective tissueInferiorly is connected to diaphragm by percardio phrenic ligamentInteriorly connected to the sternum by sterno pericardial ligamentSuperiorly,completely fused with the roots of the great vessels of the heart
22PLUERA&PERICARDIUMMost of the pericardium surface is covered pluera the lung except and area posterior to sternum at the level of 4th 5th costal cartilage .Anteriorly related to anterior mediastinum and thymus in childrenPosteriorly related to esophagus,descenting aorta
27Fibrous and serous pericardium It is a conical sac which hasBase:Attached to the central tendon of diaphragmApex:Above the heart to the level of the sternal angle4- surfaces :(anterior – posterior – 2 lateral)SerousIt is a closed serous sac and hasa parietal anda visceral layerThe visceral layer is calledepicardium
29InnervationsThe 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
31DiseasesPericarditis is inflammation of the pericardium. It can cause fluid to build up in the sac (pericardial effusion).Excessive amounts of fluid may lead to cardiac tamponadePericardio centhesis removal of fluid from the pericardial cavity by inserting a needle