Dyspnoea Laryngea. Roaring. Hemiplegia Laryngea. 149 



diminished. Distortions and fractures are usually overlooked by 

 veterinarians but from the frequency with which the author has 

 met with them in his dissection he is convinced that they deserve 

 greater attention than has been awarded them. 15th, Percivall 

 records a case of inveterate roaring in which, even tracheotomy 

 having failed to cure, the patient was destroyed and the lungs 

 found to be extensively consolidated, many of the air tubes hav- 

 ing been so compressed as to be almost impervious. I have 

 known a case of roaring from the presence of a pedunculated 

 tumor in the lower end of the windpipe where it divides to enter 

 the lungs, and the same result may ensue from the partial ob- 

 struction of the bronchial tubes by masses of tenacious mucus in 

 chronic bronchitis. i6th, Rupprecht relates a case caused by de- 

 pression of the cartilages on the left side of the larynx and twist- 

 ing of the left arytenoid cartilage, the point of which was turned 

 outward so that the upper opening of the larynx was actually 

 widened, but the lower border of the arytenoid left free, naturally 

 slid inward toward the centre of the lumen at the level of the 

 vocal cords, and thus caused the stertor. 17th, Similarly Bouley, 

 Jr., notes a case of a false joint in the middle of the arytenoid 

 cartilage, so that the detached posterior portion, was drawn into 

 the median line by the combined action of the arytenoideus, and 

 crico-arytenoideus posticus muscles. In this case the passage for 

 the air was almost entirely closed. i8th. Other causes are ossifi- 

 cation anchylosis of the laryngeal cartilages, chondritis of aryte- 

 noid or epiglottis with formation of an enchondroma, fracture of 

 a cartilage with a similar cartilaginous growth, the growth pro- 

 jecting in£b the lumen, and small cartilaginous vegetations on the 

 vocal cords. Dupuy records the presence of a mass of erectile 

 tissue in the arytenoid mucosa, and Cadeac hypertrophy with 

 contraction of the connective tissue which binds the two aryte- 

 noids together. 19th, The immediate cause of roaring in the 

 immense majority of cases is the paralysis and fatty degener- 

 ation of certain muscles on the left side of the larynx. 

 The muscles supplied with motive power by the left recurrent 

 laryngeal nerve (Crico-arytenoideus posticus, Crico-aryte- 

 noideus lateralis, thyro-arytenoideus,' and the left half of the 

 arytenoideus) are those constantly and exclusively affected, 

 while those supplied by the superior lary^igeal nerve and first cer- 



