THE EXTERNAL EAR 125 



cartilage, across the annular cartilage. It passes through the inferior 

 commissure of the concha to be distributed to the interior of the 

 latter. 



The posterior auricular nerve is also given off by the seventh nerve. 

 It follows the course of the posterior auricular artery upwards to the 

 back of the concha to supply the cervico-auriculares muscles. 



Branches of the first cervical nerve are distributed to the inner side 

 of the base of the ear, as are branches of the second cervical nerve, 

 which are also continued to supply the inner aspect. 



Diseases of the External Ear. — Wounds and other injuries of the 

 external ear are extremely common in dogs, but are not commonly met 

 with in horses. This is due mainly to the difference in conformation 

 and disposition of the conchal cartilage, which in the former animal 

 cause the flap of the ear to be pendulous, and consequently much 

 more exposed to risk of injury. 



When such injuries affect the base of the ear profuse hemorrhage 

 results, on account of the number of small vessels which ramify on 

 this part, and to arrest this it is advisable to secure and ligature the 

 anterior auricular artery and the vertical branch of the posterior 

 auricular, which may be found by dissecting between the superior 

 border of the parotid gland and the base of the cartilage. 



In cases where the cartilage has been exposed it should be pared, 

 and the cartilage should then be pressed back between the two 

 layers of skin, the edges of which are brought into apposition 

 and secured by the insertion of numerous fine interrupted sutures. 

 These will prevent corrugation of the part during the healing 

 process. 



Tumours in the external ear are by no means uncommon, and they 

 frequently give rise to much trouble and annoyance. They are usually 

 fibromata or papillomata, and they are commonly associated with a 

 most offensive odour. 



They are most frequently situate near the base of the concha, 



