Mediastinum

Introduction

Boundaries Ant– sternum Post—vertebral column Sup—Thoracic inlet Inf—Diaphragm On each side—Mediastinal pleura.

Types Superior mediastinum Inferior mediastinum 1) Anterior 2) Middle 3) Posterior

Superior mediastinum Boundaries Ant– Manubrium sterni Post—Upper 4 thoracic vertebrae Sup– Plane of thoracic inlet Inf—An imaginary plane passing through the sternal angle in front, & the lower border of the body of the 4th thoracic vertebra. On each side– Mediatinal pleura

Contents Trachea & oesophagus Muscles origins of sternohyoid, sternothyroid, lower ends of longus colli. 3) Arteries Arch of aorta, Brachiocephalic , lt common carotid, lt subclavian. 4) Veins upper half of the svc, lt superior intercostal vein 5) Nerves—vagus, phrenic, cardiac, lt recurrent laryngeal 6) Thymus 7) Thoracic duct 8) lymphnode– paratracheal, Brachiocephalic, Tracheobronchial

Anterior Mediastinum Boundaries Ant—Body of sternum Post—pericardium Sup—Imaginary plane separating the sup mediastinum from the inf. Mediastinum Inf– Sup. Surface of diaphragm On each side– Mediastinal pleura

Contents Sternopericardial ligament Internal thoracic artery(Small mediastinal branches) Thymus(Lowest part) Areolar tissue Lymph nodes & lymphatics

Middle Mediastinum Boundaries Ant– pericardium Post—oesophagus, descending thoracic aorta, azygos vein On each side– Mediastinal pleura Contents Heart Veins –svc, azygous,pulmo Nerves-phrenic,deep cardiac Tracheobronchial lymph nodes.

Posterior Mediastinum Boundaries Ant—pericardium, trachea,pulmonary vessels, diaphragm. Post—8 th thoracic vertebrae & intervening discs. On each side—Mediastinal pleura

Contents Oesophagus Arteries—descending thoracic aorta & its branches Veins—azygous , hemiazygous, accessory hemiazygous vein Nerves—vagus, splanchnic, greater, lesser & least splanchinc nerves arising from the lower 8th thoracic ganglia of the sympathetic chain Lymph nodes– post mediastinal lying alongside the aorta & thoracic duct

Clinical Anatomy Mediastinitis Mediastinal syndrome Symptoms Engorgement of veins in the upper half of the body Dyspnoea, cough Dysphagia Hoarseness of voice Intercostal neuralgia Erosion of the vertebral bodies Paralysis of the diaphragm