Anatomy of mediastinum

Mediastinum

Mediastinum is median septum of the thorax between the two lungs.

Divisons :

Mediastinum is divided intoa) Superior Mediastinum b) Inferior mediastinum

Inferior mediastinum is further divided into the anterior, middle and posterior mediastinum

* ANATOMISTS DIVIDE MEDIASTINUM INTO 4 PARTS----- SUPERIOR,AND INFERIOR COMPARTMENTS BY AN IMAGINARY LINE TRAVERSING THE MANUBRIOSTERNAL JOINT AND LOWER SURFACE OF 4TH DORSAL VERTEBRA.THE INFERIOR COMPARTMENT IS FURTHER SUBDIVIDED INTO 3 PARTS THE MIDDLE MEDIASTINUM WHICH CONTAINS PERICARDIUM AND ITS CONTENTS,AS WELL AS MAJOR VESSELS AND AIRWAYSANTERIOR MEDIASTINUM ANTERIOR TO MIDDLE MEDIASTINUM AND POSTERIOR TO STERNUM POSTERIOR MEDIASTINUM WHICH LIES POSTERIOR TO MIDDLE MEDIASTINUM AND ANTERIOR TO THORACIC VERTEBRAL COLUMN

HEITZMAN

*HEITZMAN DIVIDES MEDIASTINUM INTOTHE THORACIC INLETANTERIOR MEDIASTINUMTHE SUPRA AORTIC AREATHE INFRA AORTIC AREATHE SUPRA AZYGOS AREATHE INFRA AZYGOS AREAIN ANY METHOD THESE DIVISIONS ARE THEORITICAL RATHER THAN

PHYSICAL.THEREFORE DISEASES CAN SPREAD FROM ONE TO ANOTHER COMPARTMENT.

ANTERIOR MEDIASTINUMBOUNDED:-ANTERIORLY-----STERNUMPOSTERIOLY------PERICARDIUMSUPERIORLY------THORACIC INLETINFERIORLY------- DIAPHRAGMCONTENTS:-THYMUS LYMPHNODES FAT INTERNAL MAMMARY VSSELSMASSES CAN BE DIVIDED INTO PREVASCULAR AND PERICARDIAC

MASSES.

ANTERIOR MEDIASTINAL MASSESTHYMIC LESIONSThymomaThymic cystThymolipomaThymic hyperplasiaThymic carcinoidThymic carcinomaTERATOID LESIONSDermoid cystTeratomaEmbryonal cell carcinomaChoriocarcinoma SeminomaMixed germ cell tumorTHYROIDGoiterAdenomaCarcinoma

LYMPH NODESLymphomaMetastasisBenign nodal hyperplasiaAngioblastic lymphoid adenopathyCVSEpiardial fat padAneurysm of ascending aortaPericardial cystCardiac tumorsCYSTSOTHERSNeural tumors of vagus and phreic nervesParagangliomaMorgagnis,s herniaHemangiomaPancreatis pseodocyst

MIDDLE MEDIASTINUMBOUNDED BY:-ANTERIORLY----PERICARDIUMPOSTERIORLY---PERICADIUM ANDPOSTERIOR TRACHEAL WALLSUPERIORLY-----THORACIC INLETINFERIORLY------DIAPHRAGMCONTENTS:- HEART AND PERICARDIUM ASCEDING AND TRANSVERSE AORTA SVC IVC BRACHIOCEPHALIC VESSELS TRACHEA AND MAIN BRONCHI LYMPHNODES PHRENIC,VAGUS AND RECURRENT LARYNGEAL NERVES

MIDDLE MEDIASTINAL MASSES

LYMPHADENOPATHYMetastasisLymphomaLeukemiaoInflammatory—-TB,SAROIDOSISPRIMARY TUMORSBronchogenic caTrachea caEsophagus caDuplication cystsEnteric cystsBronchogenic cystsVASCULAR LESONSAneurysmsHematomaDistended veinsLeft sided svc

POSTERIOR MEDIASTINUMBOUNDED :-ANTERIORLY------POSTERIOR TRACHEA AND PERICARDIUMANTEROINFERIORLY---DIAPHRAGMPOSTERIORLY-----VERTEBRAL COLUMNSUPERIORLY----THORACIC INLETCONTENTS:-ESOPHAGUSDESCENDING AORTAAZYGOS,HEMIAZYGOS VEINTHORACIC DUCTVAGUS AND SPLANCHNIC NERVESFATLYMPHNODES

POSTERIOR MEDIASTINAL MASSES

TRAUMAThoracic aneurysmHematomaLoculated hemothoraxTraumatic pseudomeningocele DEVELOPMENTAL LESIONEnteric cystsNeurenteric cystBronchogenic cystExtra lobar sequestrationABDOMINAL DISEASEBochdalek herniaPancreatic pseudo cystRetroperitoneal massOTHERSExtra medullaryhematopoisesLateral meningocele

NEOPASMSNEUROGENIC TUMORS ganglion series tumors nerve root tumors paragangliomaMETASTASISLYMPHOMASMESENCHYMAL TUMORSTHYROID LESIONSHEMANGIOMASVERTEBRAL TUMORSINFLAMMATIONParaspinous abscessMediastinitisSarcoidosisLymphoid hyperplasiaVASCULAR LESIONAneurysm of descending aorta

Anterior mediastinal masses(50%).The anterior mediastinal masses usually displaced the anterior junctional line, obliterate the cardiophrenic angle and the retro-sternal space with hilum overlay sign.1- Retro-sternal goiter. 2- Tortuous innominate artery.3- Fat deposition. 4- Enlarged lymph nodes.5- Ascending aortic aneurysm.6- Thymoma.7- Germ cell tumour.8- Pleuro-pericardial cyst.9- Morgagni hernia.10- Para-thyroid adenoma.

Middle mediastinal masses(25%). The middle mediastinal masses widened the para-tracheal stripes, displaced the azygo-oesophageal recess on right side.

1- Lymph nodes enlargement.2- Aortic arch aneurysm.3- Enlarged pulmonary artery.4- Dilated superior vena cava.5- Bronchogenic cyst.6- Tracheal lesions.7- Cardiac tumours.

Posterior mediastinal masses(25%).1- Neurogenic tumours.2- Pharyngio-esophygeal pouch.3- Descending thoracic aortic aneurysm.4- Hiatus hernia.5- Esophageal lesions.6- Para-vertebral masses.7- Neuroenteric cysts.8- Bochdalek hernia.9- Pancreatic pseudocyst.10- Abscess.11- Fibrosis.12- Extra-medullary hematopoiesis.13- Lateral meningocele.

Posterior mediastinal schwannoma.

Bochdalek's hernia.

Lymph nodes