Lung. 127 



mogastric nerve, while below, is the ligamentum pulmon- 

 alum latum. On the left side the relations are : In front, 

 the anterior pulmonary plexus and the phrenic nerve; 

 above, the arch of the aorta; behind, the posterior pul- 

 monary plexus, the pneumogastric nerve and the de- 

 scending aorta ; while below, is the ligamentum pulmonal- 

 um latum. The right lung has a chief or greater fissure 

 running from the posterior border, near the apex, down- 

 wards and forwards to the inferior border, and a lesser 

 fissure, beginning about the middle of the former, and 

 passing forwards to the anterior border of the lung. 

 The right lung is, therefore, divided into three lobes up- 

 per, middle and lower by means of these two fissures, 

 whereas the left lung is divided into two lobes only, an 

 upper and a lower one, by a fissure, which, beginning near 

 the upper part of the posterior border, runs downwards 

 and forwards to the lower part of the anterior border of 

 this lung. 



Landmarks for the Lungs. To trace the anterior 

 border, begin at the apex, i.e., at a point about one inch 

 above the clavicle, and a little nearer the posterior than 

 the anterior border of the sterno-mastoid muscle, and 

 draw a line, downwards and forwards, towards and cross- 

 ing the sterno-clavicular articulation and the outer edge 

 of the manubrium. This can represent the outline of the 

 upper part of the anterior border of each lung. Continue 

 these lines for the upper part of the anterior borders 

 downwards, so as to nearly meet opposite the second cos- 

 tal cartilage, i.e., at the junction of the manubrium and 

 the gladiolus. Prolong these lines down the sternum, still 

 nearly touching one another, until the fourth costal car- 

 tilage is reached, at which point, the left border leaves the 

 sternum and passes outwards, in a manner to be described 

 presently. The line for the right lung passes down, in 



