202 THE POCKET ANATOMY 



Contents. Anterior mediastinal glands. 



The middle mediastinum contains the pericardium with its 

 contents, the phrenic nerves and accompanying vessels, the 

 arch of the vena azygos major, the roots of the lungs and 

 bronchial lymphatic glands. 



The posterior mediastinum lies behind the pericardium. 



Boundaries : 



In front. Pericardium and roots of lungs, and diaphragm 

 (below). 



Behind. Spinal column, from the lower border of the 4th 

 dorsal to the i2th dorsal vertebra. 



Laterally. Pleura. 



Below. Diaphragm covered by pleura. 



Above. Plane passing forwards from lower border of 4th 

 dorsal vertebra. 



Contents. Descending thoracic aorta and some of its right 

 intercostal branches, ossophagus, pneumogastric and great 

 splanchnic nerves, the three azygos veins, thoracic duct, and 

 posterior mediastinal glands. 



THE HEART AND PERICARDIUM 



THE PERICARDIUM. 



The pericardium is a nbro-serous membrane, containing 

 the heart and the commencement of the great vessels. The 

 apex points upwards and surrounds the ascending aorta, 

 superior vena cava, and pulmonary artery for about 2 inches 

 i.e., to the level of the lower border of the aortic arch. 

 The base is fixed to the central tendon and adjoining muscular 

 fibres of the diaphragm. 



In front. Behtnd. Laterally. 



Gladiolus. Roots of lungs. Pleura. 



Left costal car- CEsophagus. Comes nervi phre- 



tilages (4th to Descending aorta. nici vessels. 



yth). Phrenic nerve. 



Remains of thy- 



mus gland. 

 Overlapped by 



both lungs and 



pleurae. 



