SECTION IV. 



THE ORGANS OF CIRCULATION. 



SEMIOLOGY OF THE ORGANS OF CIRCULATION. 



The semiology of the circulatory apparatus comprises the clinical 

 examination of the heart, arteries and veins, and the examination of the 

 pulse and blood. 



Heart. In animals of the bovine species, the heart is situated in the 

 thoracic cavity opposite the third, fourth, fifth and sixth ribs, nearly in 

 the median plane of the thorax, and inclined from front to back at an 

 angle of 70 degrees. 



The pericardial sac touches the extremity of the sternum where it is 

 in immediate contact with the lower insertion of the diaphragm. This 

 peculiar arrangement favours the development of pericarditis due to 

 foreign bodies. 



On the left side the pericardial sac may come in direct contact with 

 the internal surface of the thoracic cavity opposite the lower extremity of 

 the third, fourth, and sometimes fifth ribs. At all other points the 

 pulmonary lobes, as expanded during inspiration, separate it from the 

 thoracic wall. 



Although the pericardium and heart are situated in the median plane, 

 percussion and auscultation should be performed on the left side, since 

 the anterior and cardiac lobes of the left lung are less developed than 

 those of the right ; but the heart can be auscultated on the right side, as 

 is advisable at times. 



In the healthy ox there exists an area of the left thoracic wall which 

 may be called the cardiac zone, on a level with which are heard the 

 normal heart sounds. In diseased conditions this zone or area may 

 vary in size, and the sounds may be modified. 



The heart can be examined by inspection, palpation, percussion, 

 and auscultation. 



Under ordinary conditions inspection reveals nothing in well-nourished 

 animals ; but in very thin subjects and in those suffering from recent 

 cardiac lesions or pseudo-pericarditis, a rhythmic movement of the chest 

 wall is sometimes detected. 



