342 



ANATOMY AND PHYSIOLOGY 



and to cover the front of the eyeball. The portion which lines 

 the lids is the palpebral conjunctiva, that which covers the ball 

 is the bulbar or ocular conjunctiva. 



The tar sal glands are in the tarsal plates; their oily secretion 



Superior lacrimal gland 

 Inferior lacrimal gland 



Ducts from superior 

 gland 



Upper eyelid partly 

 divested of skin 



Upper punctum 



Lacrimal sac, near its 

 fundus 



Common duct, formed 

 by junction of upper 

 and lower ducts 



Lower punctum 



Naso-lacrimal duct 



FIG. 221. LACRIMAL APPARATUS. (Morris.) 



prevents the lids from adhering to each other. (They are called 

 Meibomian glands.} 



The angles formed by the extremities of the eyelids are the 

 medial and the lateral angles (inner and outer canthi). At the 

 medial angle, each lid presents a small elevation, the lacrimal 



FIG. 222. THE MUSCLES OF THE EYEBALL. (Holden.) \ 

 A small section of the upper eyelid is shown. 



papilla, with a minute opening (punctum) where the tears enter a 

 small canal which leads to the lacrimal sac; from the lacrimal sac 

 they flow through the nasal duct to the nasal cavity. 



The eyelashes, or cilia, are kept soft and flexible by an oily 



