80 CLINICAL DIAGNOSTICS. 



The ju,c:ulars can be distended to the size of the human 

 wrist, or even the arm, appearing as great, round strands. 

 The veins of the conjunctiva can also be distended, being rec- 

 ognized as ramiform, often contorted, bluish strands in the 

 mucous membrane. 



The veins are generally distended : 



1. In valvular disease (tricuspid). It is usually sec- 

 ondary, but in the ox mostly primary. 



2. In chronic pulmonary diseases interfering with cir- 

 culation : emphysema. 



3. In diseases of the heart's muscle, the organ having 

 become so weak that it is unable to handle the quantity of 

 blood : traumatic myocarditis of the ox. 



■i. From excessive intrathoracic pressure upon the heart 

 and large blood vessels : tympanitis, plcuritis, pericarditis 

 traumatica of the ox. 



Pulsation in veins. Besides being distended, veins 

 can show pulsation under some circumstances. Synchronous 

 with the respirations, and independent of the heart's action, 

 a slight swelling of the jugulars occurs during the act of 

 expiration, to fall again at inspiration. A so-called jugular 

 pulse is normal in the ox for the following reasons : The 

 jugulars and anterior vena cava in this animal are compara- 

 tively large. The continual flow of the venous blood into 

 the right heart suffers during the systole of the right auricle, 

 which slightly precedes that of the ventricle, a momentary 

 interruption, the blood congesting in the anterior vena cava 

 and jugulars, causing a brief distention of the jugulars, sim- 

 ulating a pulsation. It is therefore not an active pulsation, 

 but merely a passive undulation due to a regurgitation of the 

 blood in the form of waves. The presystolic appearance of 

 the pulse movement characterizes it, therefore it should al- 

 ways be compared with the arterial pulse. The collapse of 

 the vein is synchronous with the arterial pulse. 



The undulation of the jugular vein is intensified in the 



