CHAPTER XIII. 
THE EAR. 
THE ear of the horse is divided into several parts. The 
inner part, or drum of the ear, is situated in the 
hardest bone of the body, called the petrosal. The 
nerve which passes into the drum of the ear and 
gives the sense of hearing, is called the auditory nerve. From 
the drum a small opening passes out into the outer part of 
the ear; this is the portion which is seen on top of the head. 
It is made up of a membrane known as the cartilage, which 
gives the ear its stiffness. This cartilage is covered hy a 
fine, delicate skin, covered on the outside by fine, short hair. 
Situated on the inner side of the outer ear are numerous long 
hairs projecting outward, the use of which is to keep foreign 
bodies from dropping into the ear. The ear is moved back- 
ward and forward by small muscles which are attached 
around it. 
