MEDIASTINUM 14.12.08 . Dr.Kvk

Defination:- 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.

DIVISIONS 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.

INFERIOR MEDIASTINUM Due to the presence of pericardium and heart it is further divided into:- Anterior mediastinum,infront of heart Middle mediastinum,pericardium &heart. Posterior mediastinum, behind the heart.

DIVISION OF MEDIASTINUM Superior mediastinum, Middle mediastinum, Anterior mediastinum, Posterior mediastinum.

Structures in the mediastinum Thymus gland in children (anterior) Pericardial sack,heart,vessels(middle) Esophagus,aorta,thoracic duct,azygos vein(posterior) Trachea, great vessels(superior)

SUPERIOR MEDIASTINUM It lies above the transverse thoracic plane. It contains aortic arches, thymus, terminal part of S.V.C.,brachiocephalic veins,Trachea and esophagus.

Structures in the superior meidiastinum

Thymus Thymus is located in the anterior mediastinum between the pericardium and sternum Thymus is present only in children After puberty thymus degenarates

Structures in the posterior mediastinum

ANTERIOR MEDIASTINUM It contains loose areolar connective tissue, Lymphatic vessels, 2-3 anterior mediastinal lymph nodes. Branches of internal mammary artery, Pulmonary arteries,pulmonary veins, Phrenic nerves.

POSTERIOR MEDIASTINUM Thoracic part of aorta, Azygous and hemiazygous veins, Vagus and splancnic nerves, Esophagus, Thoracic duct and lymph nodes.

Esophagus &plexus

Descending thoracic aorta

APPLIED ANATOMY Tumours 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.

Anatomy Lecture Pericardium 14.12.08

Pericardium Is a double-walled sac that contains the heart and the roots of the great vessels.

Layers of pericardium

PERICARDIUM Peri= around Cardium= heart It is a fibro-serous sac which surround the Heart and the roots of the large vessels It consist of: 1- The fibrous pericardium 2-The serous pericardium two layer: parietal layer Visceral layer 3- the sinuses of the pericardium (transverse – oblique )

FIBROUS &SEROUS PERICARDIUM Fibrous pericardium is made up of dense conective tissue Inferiorly is connected to diaphragm by percardio phrenic ligament Interiorly connected to the sternum by sterno pericardial ligament Superiorly,completely fused with the roots of the great vessels of the heart

PLUERA&PERICARDIUM Most 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 children Posteriorly related to esophagus,descenting aorta

PERICARDIUM&PHRENIC NERVE

Formation of pericardial cavity

Fibrous and serous pericardium It is a conical sac which has Base: Attached to the central tendon of diaphragm Apex: Above the heart to the level of the sternal angle 4- surfaces : (anterior – posterior – 2 lateral) Serous It is a closed serous sac and has a parietal and a visceral layer The visceral layer is called epicardium

PERICARDIUM AFTER REMOVAL OF THE HEART

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

Diseases Pericarditis 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 tamponade Pericardio centhesis removal of fluid from the pericardial cavity by inserting a needle

THANKYOU Dr.KUMAR Associate Professor thankyou