IMPORTANCE OF COUGH IN A CLINICAL SENSE. 
549 
Of primary importance in the production of cough is the 
vagus, as it supplies with sensation the pleura and the mucous 
membrane of the trachea and parts below 5 the supcvioT laTyn^ 
s^eal nevves also come into consideration, as they constitute the 
sensory apparatus of the laryngeal mucosa. Cough due to cen¬ 
tral irritation is rare. The same refers to cough finding its 
origin in irritative processes located in the ovaries, uterus, blad¬ 
der, stomach, external auditory meatus and nasal cavity. 
The quality of cough varies very much in the domestic ani¬ 
mals ; this depends on the anatomical arrangement of the vocal 
cords, the pharyngeal and buccal cavities and sinuses of the 
head. Thus the cough of the horse is sonorous and short, while 
the ox produces a weaker and dull sound. 
Classification of Coughs .— 
I* From an anatomical point of view i Open glottis cough j 
closed glottis cough. 
2 . From a regional point of view : Laryngeal cough. Tra¬ 
cheal cough. Thoracic cough ; {ci^ bronchial, {Ip pulmonary. 
3. As to its course : Acute cough, chronic cough. 
4. As to its origin : Spontaneous cough, artificial cough. 
^ 5. As to its properties: Long or short; strong or weak ; pain¬ 
ful or painless ; dry, tight, or moist and loose, frequent or occa¬ 
sional, hollow, barking, wheezing, paroxysmal, strangling, eva¬ 
sive and suppressed. 
The irritating agent may be introduced from without, such 
as dust, smoke, gases, medicines improperly administered, etc. ; 
or the agent may arise within, as inflammatory’products from 
the lungs or bronchi, which, on reaching a sensitive mucous 
membrane, as that of the larynx, for instance, stimulate the 
cough centre. The laryngeal mucous membrane requires but 
little irritation to produce cough when either acutely or chron¬ 
ically diseased. Quick movements, as getting up, turning the 
head suddenly, drinking water, especially when cold, cause 
coughing. 
From a clinical standpoint cough is of value as it helps to 
determine the region, the extent, the intensity and frequently 
