THE THORAX AND PLEUREZ—THE LUNGS - 547 
THE THORAX AND PLEURZ 
The ribs are in general strongly curved in most of the improved breeds, so that 
the thorax is rounded. The pleural sacs extend forward to the first intercostal 
space. The diaphragmatic line of pleural reflection begins at or a little above the 
sternal end of the seventh rib, and extends in a gentle curve to about the middle of 
the last rib, along the medial face of which it continues. (When a fifteenth rib is 
present—a very common occurrence—it does not affect the arrangement of the 
pleura or diaphragm). 
Trachea (Esophagus 
Apical lobe 
Cardiac lobe 
Cardiac lobe 
Diaphrag- 
— matic lobe 
Fic. 486.—Lunes anp Heart or Pic; VENTRAL VIEW. 
£.%., Intermediate lobe of right lung; F. d., diaphragmatic surface of lungs; 1, left brachial artery; 2, brachio- 
cephalic artery; 3, apex of heart; 4, pericardium (cut edge); 5, plica ven cave; 6, posterior vena cava; 7, esophagus; 
8, ventral cesophageal nerve trunk; 9, aorta. 
THE LUNGS 
The right lung has four lobes—apical, cardiac, diaphragmatic, and intermedi- 
ate. Tn some cases the apical lobe is divided by a fissure into two parts; sometimes 
it is fused with the cardiac lobe. The left lung may be regarded as having two or 
three lobes. The diaphragmatic lobe is clearly marked off by a fissure. The part 
