UPPER EXTREMITY AND THORAX, ANTERIOR. 263 



the lungs would begin over the middle of the clavicles, 

 pass upward and inward for a distance of three-fourths of 

 an inch until over the sternal end of the clavicles, then 

 drawn downward and inward, crossing the sternoclavicular 

 articulations, toward the middle line of the body, to meet at 

 the level of the upper border of the second cartilages (junc- 

 tion of first and second pieces of the sternum). The 

 anterior borders of the two lungs lie in contact (separated 

 by the pleurae) from this point to the level of the middle 

 of the sternum (the mid-point between the fourth carti- 

 lages). From here they separate, due to the presence of a 

 notch in the anterior border of the left lung for the accom- 

 modation of the heart. The right continues directly down- 

 ward to the sternal end of the sixth cartilage. The left 

 turns outward and downward along the upper border of the 

 fifth cartilage until it reaches a distance of one and one-half 

 inches from the middle line, when it turns downward to the 

 upper margin of the sixth rib three inches from the median 

 line. Each lung is divided into two main lobes by the 

 great fissure and the right has in addition a third lobe cut 

 off by a secondary fissure. 



The great fissure is indicated on the chest by drawing 

 a line from the third do-rsal spine obliquely downward and 

 forward to the sixth costochondral articulation, for the left 

 side ; and from the fourth dorsal spine to the seventh costo- 

 chondral joint on the right side. The secondary fissure, 

 on the right side, is drawn from the angle of the sixth to the 

 cartilage of the fourth rib. The lower border of the lungs 

 is represented by a line drawn around the chest diagonally 

 from the sixth cartilage at the sternum, to the tenth dorsal 

 spine behind. On the left side this line represents the 

 lower border also, but it should be started at a distance 

 of three inches from the middle line. This entire border 



