Central compartment of the thoracic cavity between the pleural cavities

Contains all the thoracic viscera and structures except the lungs

Extends from superior thoracic aperture to the diaphragm inferiorly

Extends from sternum and costal cartilage anteriorly to the bodies of thoracic vertebrae posteriorly

For descriptive purposes, divided by imaginary plane passing thru sternal angle and lower border of T4 vertebra

Superior mediastinum

Inferior mediastinum

Inferior mediastinum subdivided by fibrous pericardium into

Anterior

Middle

posterior

Above the sternal angle

Major contents from anterior to posterior

Thymus gland

Large veins (brachiocephalic, SVC)

Large arteries (arch of aorta and roots of major branches)

Trachea

Esophagus and thoracic duct

Sympathetic trunks

Smallest subdivision of the mediastinum

Lies between body of sternum and the pericardium posteriorly

Consists of loose connective tissue, fat, lymphatic vessels and nodes, inferior part of thymus in infants and children

Contains the pericardium, heart and roots of great vessels (ascending aorta, pulmonary trunk and SVC)

Located posterior to the pericardium and anterior to the bodies of the inferior eight vertebrae

Contains thoracic aorta, thoracic duct, posterior mediastinal lymph nodes, azygos and hemiazygos vein, esophagus, thoracic sympathetic trunks