ANATOMY OF THE ABDOMEN. 225 



lung. The portion of lung occupies the space between the 

 inferior mediastinum and the posterior cava ; i i, &c. the first 

 seven of the costse, or true ribs, divided ; jj, the remaining 

 ribs ; where the letters are placed would be the posterior 

 lobes of the lungs ; A:, the cartilages of a few of the ribs, and 

 of the sternum sawn through to expose the contents of the 

 chest ; /, the ensiform cartilage of the sternum ; m, the 

 skin dissected back ; n, the coronary artery of the heart, 

 which has been deprived of the outer layer of pericardium. 



ANATOMY OF THE ABDOMEN. 



OF THE ABDOMEN GENERALLY. 



The external parts of the abdomen are the common 

 integuments ; the abdominal muscles ; the parts of genera- 

 tion in the horse, and the mammae in the mare. The 

 internal parts are the various viscera and their appendages. 

 The abdominal cavity, when its contents are removed 

 {Plate IV.), presents an extensive oval vault, bounded 

 anteriorly by the diaphragm ; posteriorly by the bones of 

 the pelvis ; superiorly by the vertebrae ; laterally by the ribs 

 and muscles of the belly ; and interiorly by the abdominal 

 muscles. This cavity, for the convenience of anatomical 

 and surgical description, is divided into imaginary compart- 

 ments or regions. 



The epigastric region (centre, right and left) includes the 

 anterior third of the abdomen. Minor divisions have dis- 

 tinct names ; and the two sides of the epigastric region are 

 set down as the right and left hypochondriacs. The central 

 third of the belly forms the umbilical region : the lateral 

 parts of the umbilical region are also termed the lumbar 

 regions. The hypogastric region extends behind an imagi- 

 nary line, drawn from the anterior spinous process of the 

 ilium upon one side, to the same bone upon the opposite 

 side of the animal ; and admits of lateral divisions into the 

 right and left iliac regions, intersected by a middle portion, 

 known as the pubic region; consequently the term hypo- 

 gastric is only general, and the subdivisions are in it entirely 

 forgotten. The central portion of these regions is divided 

 by a white line called the linea alba. 



The relative situation of the viscera within the regions 



Q 



