THE PLEUE^E. 



1085 



At a lower level the innominate and subclavian veins also lie upon its medial and 

 ventral aspects. 



The cupula pleurae is strengthened and held in place by an aponeurotic expansion, first 

 described by Sibson, which is spread over it, and is attached to the internal concave margin 

 of the first rib. This fascia is derived from a small muscular slip which takes origin from 

 the transverse 

 process of the 

 seventh cervical 

 vertebra. 



Right vagus nerve Trachea 



Right subclavian 

 arter 



(Esophagus Left subclavian artery 



Icus subclavius 



Right 



COS- innominate vein 

 Innominate 

 artery 



ft vagus nerve 



ft common 

 carotid artery 

 Left inno- 

 minate vein 



Pleura Cos- 

 talis. The 

 tal pleura is the 

 strongest and 



, thickest part of 

 the parietal 

 pleura. It lines 

 the internal sur- 



; faces of the cos- 

 tal arches and of 

 the intervening 

 intercostal mus- 

 cles. Ventrally 

 it reaches the 

 sternum, whilst 

 dorsally it passes 

 from the ribs 

 over the sides of 

 the bodies of the 

 vertebrae. It is 



. easily detached 

 from the parts 



; which it covers, 



, except as it 

 passes from the 

 heads of the ribs 



, on to the ver- 

 tebral column. 

 There it is some- 

 what tightly 



, bound down. 



Pleura Dia- 

 phragmatica. 

 The diaphragm- 

 atic pleura covers 



i that portion of 

 the thoracic sur- 

 face of the dia- F IG . 863. DISSECTION OF A SUBJECT HARDENED BY FORMALIN INJECTION, to show the 

 phragm which relations of the two pleural sacs, as viewed from the front. The anterior and 



o lafoT-ol diaphragmatic lines of pleural reflection are exhibited by black dotted lines, whilst 



the outlines of the lungs and their fissures are indicated by the blue lines. 



side of the base 



of the pericardium, but it does not dip down to the bottom of the narrow interval 

 between the thoracic wall and the diaphragm. In other words, a strip of the 

 ; thoracic surface of the diaphragm adjoining its costal attachment is left uncovered. 

 Pleura Mediastinalis. The mediastinal pleura extends from the dorsal surface 

 of the ventral thoracic wall to the vertebral column, and clothes the side of the 

 mediastinal septum, which intervenes between the two pleural cavities. It is con- 

 tinuous with the costal pleura of its own side, both ventrally and dorsally, 

 two lines which are respectively termed the sternal and vertebral lines of 



