Pig. Ii6. Boundaries of the Lungs and Pleurae as seen from in front. 

 Area of Absolute Cardiac Dulness. 



The Parietal Pleura consists of the Costal Pleura, the Diaphragmatic 

 Pleura, the Mediastinal (including the Pericardial) Pleura and the Apical Pleura. 



The knowledge of the reflections of the Pleura, i. e. the lines upon the 

 Anterior Thoracic WaU at which the Costal Pleura becomes the Diaphragmatic 

 and the Mediastinal Pleura — cf. dotted lines in the figure — is important. 



The Anterior (Median) Boundary of the right costal pleura extends from 

 the upper margin of the ist costal cartilage at an angle of 45" downwards and 

 inwards to a point Vio^h to i inch to the left of the middle line at the angle 

 of the Sternum (Junction of Manubrium and Body of Sternum). From this point 

 it continues downwards in a vertical direction, gradually approaching the middle 

 line at the level of the 5th Costo-Sternal Articulation ; from this point its course 

 is slightly downwards along the lower border of the 6th costal cartilage in the 

 6th intercostal space or along the upper border of the 7th costal cartilage, the 

 lower border of which it reaches about -ys^J^ "f an inch mesial to its costo- 

 chondral junction. 



The costal cartilage of the 7 th rib, like the lower costal cartilages, is 

 almost entirely devoid of Pleura. This also applies to an increasing surface of the 

 ribs themselves as we get lower in the series (27,1 inches). The limit of the Pleura 

 crosses the right nipple line (cf. Fig. iii) at the lower margin of the 6th costal 

 cartilage or slightly lower down, and the axillary line at the lower border of the 

 9th Costal Cartilage. 



In tlie upper part, the left costal pleura takes a similar course; it crosses 

 the Sternal Angle (LUDWiGs Angle) a little further to tlie left; from this point 

 it passes so as to often reach the middle line, becoming, to some degree, adherent 

 to tlie pleura of the opposite side; for the distance of 2 inches it extends ver- 

 tically downwards until it reaches the level of the 4th costal cartilage; at this 

 level the margin of the pleura extends obliquely downwards and outwards to the 

 upper border of the 5th Costochondral Articulation whence it curves with its 

 concavity inwards to the upper border of the 7th Costal Cartilage ; from this point 

 it again follows a similar course to the Right Pleura downwards and outwards; 

 though mesially it does not reach the 7th Costal Cartilage it may extend lower 

 down externally. The left pleura crosses tlie axiUary Une at the loth rib or in 

 the gtli interspace (cf. Fig. 126). The pink area indicates Absolute Cardiac Dulness 

 wliich under normal conditions is not encroached upon by lung tissue and which 

 area serves for the exposure of the Pericardium in Pericardiotomy. Cf. Figs. 70 

 and 121 for a description of the Apical Pleurae. 



The boundaries between tlie different lobes are shewn in the figure. 



The Right Lung has three lobes — the superior and middle lobes are 

 separated anteriorly by a fissure which extends to the level of the 4th rib or 

 1/2 inch lower. The boundary between the middle and inferior lobes lies opposite 

 the 6th intercostal space and extends behind tlie anterior extremity of the 7 th 

 rib obUquely downwards to the lower border of the lung. 



The Left Lung consists of 2 lobes and the fissure which separates them 

 extends from the posterior end of the 4th interspace to the region behind the 7 th 

 costal cartilage. 



