Mediastinum Dr. Sama ul Haque Dr Rania Gabr

Objectives Define mediastinum. Enlist the divisions of mediastinum. Describe the boundaries and contents of mediastinum.

Lateral view of Thorax

Mediastinum Definition: A median septum or median partition between the two pleural cavities. It includes all the structures which lie in the intermediate compartments of the thoracic cavity

Boundaries of the Mediastinum Superior boundary: Superior thoracic aperture Inferior boundary: Diaphragm Anterior boundary: Sternum Posterior boundary: Bodies of vertebrae T1 to T12 Lateral boundaries: Mediastinal parietal pleura (left and right).

Divisions of Mediastinum Superior mediastinum: Above the imaginary plane between the sternal angle and the lower border of the 4th thoracic vertebra.

Divisions of Mediastinum Inferior mediastinum: Below the imaginary plane and it is further subdivided into: a. Anterior mediastinum: Behind the body and xiphoid process of the sternum and in front of the middle mediastinum (pericardium). b. Middle mediastinum: Contains pericardium, heart and the roots of the great vessels. c. Posterior mediastinum: lies behind the middle mediastinum (the part that lies posterior to the pericardium and anterior to the bodies of vertebrae T5 to T12).

Mediastinum

Divisions of Mediastinum

Contents of the Superior Mediastinum From post. to ant.: Esophagus Trachea Arch of Aorta: and its 3 brs: 1- Brachiocephalic artery 2- Left common carotid artery 3- Left subclavian artery Brachiocephalic veins Superior vena cava Remains of Thymus Nerves: Phrenic nerves: rt and lt Vagus nerves: rt and lt Left recurrent laryngeal nerve Sympathetic trunk Others Lymph nodes and Thoracic duct

Superior Mediastinum

Superior Mediastinum

Inferior Mediastinum

Inferior Mediastinum

Inferior Mediastinum (Lateral view)

Anterior Mediastinum Sternopericardial ligaments Lymph nodes Remains of thymus

Middle Mediastinum (Lateral view) Pericardium Heart Arteries: Roots of the great vessels: aorta and pulmonary art. Veins: lower half of superior vena cava, terminations of inferior vena cava & pulmonary veins Nerves: Phrenic nerves Bifurcation of trachea Lymph nodes

Posterior Mediastinum Descending thoracic Aorta Esophagus: most anterior Thoracic duct Azygous vein Hemiazygous vein Vagus nerves Rt and lt Sympathetic trunks and their brs: splanchnic nerves Lymph nodes

Posterior Mediastinum

Posterior Mediastinum

Posterior Mediastinum

Posterior Mediastinum

Positional changes of Mediastinum