THE SENSE OF SIGHT ' 397 



from before backward. Behind it receives the optic 

 nerve (the nerve of the sense of sight), and in front 

 are the eyelids, eyebrows, etc., which comprise the 

 so-called appendages of the eye. 



The Appendages of the Eye. These include the 

 eyebrows, eyelids, conjunctiva, the lacrymal gland 

 and sac, and the nasal duct. The last three belong 

 to the "lacrymal apparatus." 



The eyebrows (supercilia) are two prominent tracts 

 of skin above the orbit, covered by thick hairs. They 

 are connected with the orbicularis, palpebrarum cor- 

 rugator supercilii, and occipitofrontalis muscles. 



The lids (palpebras) protect the eyeball. Each is 

 composed of thin skin, areolar tissue, muscular fibers, 

 the tarsal cartilage and ligament, Meibomian glands, 

 and conjunctiva; the upper lid, which is also the more 

 movable, contains, in addition, the aponeurosis of the 

 levator palpebrse muscle. 



The lids are separated, when opened, by a 

 space, the fissura palpebrarum, and are united at the 

 angles (canthi). The outer angle is sharp, and the 

 inner is more obtuse. At the inner angle on each 

 lid is found the lacrymal tubercle, pierced by the 

 punctum lacrymale, the upper opening of the lacrymal 

 canal. 



The tarsal cartilages (tarsi) are two plates of dense 

 fibrous tissue, one in each lid. 



The tendo oculi or palpebrarum is Y-shaped. The 

 stem is attached to the nasal process of the superior 

 maxilla, and each arm to one of the tarsal cartilages. 



The palpebral ligament is a fibrous membrane 

 attached to the tarsal cartilages and to the correspond- 

 ing margin of the orbit. 



The Meibomian glands (sebaceous) lie on the inner 

 surface of the lids, between the tarsal cartilages and 

 the mucous membrane. In the upper lid there are 

 about thirty; in the lower, fewer. 



