176 ANATOMY OF THE HEAD. 



THE EAR. 



The ears are formed of an inner and outer part. The 

 form of the outer ear is very wisely adapted to the various 

 habits and manners of the animal. The external ear in the 

 horse presents a most advantageous form for catching the 

 slightest sound ; it is moveable ; and hearing appears to be 

 the only double sense that is equally true when the organ of 

 one side alone is used ; for the horse is commonly seen with 

 one ear directed forward and the other backward. The 

 hair, within the tube, is long and fine, and guards it from 

 the attack of insects, and the entrance of dust or dirt ; 

 hence the clipping of this hair may prove very prejudicial : 

 the inside of the ear is also furnished with a peculiar kind 

 of gland, which secretes a whitish substance. 



The cartilages of the ear are three. The concha is that 

 conical body which gives to the ear its figure ; it is covered 

 by the skin and muscles. This cartilage is attached to the 

 cranium, through the annular cartilage, with which last it is 

 connected through ligamentous union. Within, and at the 

 base of the concha, is the annular cartilage ; a small move- 

 able body, whereby the external cavity, around which the 

 cartilage is placed, is rendered more tortuous. The angular 

 cartilage is situated upon the forehead ; upon which it is 

 moved, and with it the other cartilages are connected. 



Muscles of the ear. The cartilages are moved by 

 muscles, of which there are several, as the following descrip- 

 tion will sufficiently prove. 



Attollens maximus. Origin. From a central line upon 

 the forehead ; from the frontal fascia ; and from the frontal 

 arch. Insertions. Into the triangular and conchal cartilages. 

 Action. To adduct the concha, and draw the triangular 

 cartilage upward and forward. This muscle may be sepa- 

 rated into several layers. 



Attollens medius. Origin. By two heads from the zygo- 

 matic arch. Insertion. Into the angular cartilage, its dor- 

 sum, border, venter, and anterior angle. Action. Acting by 

 itself to draw the triangular cartilage downward and for- 

 ward ; acting with the maximus to render the angular 

 cartilage firm. 



Attollens inferior. Origin. From the centre of the 



