CHAPTER VIII 



THE EYE AND EXTERNAL EAR 



THE EYE AND ITS APPENDAGES 



The 'Eyelids. — The function of these structures is to protect the 

 eyeball. It should be remembered that the upper lid has much the 

 greater range of movement. Plate XXVIII. shows the structure of 

 the lid, and on reference to the plate it is seen that the structures 

 which form the lid from without inwards, or before backwards, are : 



Skin. 



Orbicularis palpebrarum muscle. 



Tarsal cartilage, palpebral ligament and the tendon of the 

 levator muscle of the upper lid. 



Meibomian glands. 



Conjunctiva. 

 Normally, the inner aspect of the eyelid should be moulded 

 perfectly on the anterior surface of the eyeball. Occasionally in 

 horses, and very commonly in some of the larger breeds of dogs, e.g.^ 

 Mastiffs, Bloodhounds and Newfoundlands, this conformation is 

 departed from and we get either an incurving or outcurving of the 

 lid. The former is the condition which is by far the more frequently 

 met with. It constitutes the affection known as Entropion^ and the 

 incurved edge of the lid proves a constant source of irritation to the 

 anterior surface of the cornea. 



