LACHRYMAL APPARATUS. 505 



the lachrymal gland ; along the edges of the lids it is continuous with 

 the mucous lining of the Meibomian glands, and at the inner angle of 

 the eye may be followed through the lachrymal canals into the lachry- 

 mal sac, and thence downwards through the nasal duct into the infe- 

 rior meatus of the nose. 



The Caruncula lachrymalis is the small reddish body which occupies 

 the lacus lachrymalis at the inner canthus of the eye. In health it 

 presents a bright pink tint ; in sickness it loses its colour and becomes 

 pale. It consists of an assemblage of follicles similar to the Meibomian 

 glands, embedded in a fibro-cartilaginous tissue, and is the source of 

 the whitish secretion which so constantly forms at the inner angle of 

 the eye. It is covered with minute hairs which are sometimes so long 

 as to be distinctly visible to the naked eye. 



Immediately to the outer side of the caruncula is a slight duplica- 

 ture of the conjunctiva, called plica semilunaris, which contains a 

 minute plate of cartilage, and is the rudiment of the third lid of 

 animals, the membrana nictitans of birds. 



Vessels and nerves. The palpebrse are supplied internally with 

 arteries from the ophthalmic, and externally from the facial and 

 transverse facial. Their nerves are branches of the fifth and of the 

 facial. 



LACHRYMAL APPARATUS. 



The Lachrymal apparatus consists of the lachrymal gland with its 

 excretory ducts ; the puncta lachrymalia, and lachrymal canals ; the 

 lachrymal sac and nasal duct. 



The Lachrymal gland is situated at the upper and outer angle of 

 the orbit, and consists of two portions, orbital and palpebral. The 

 orbital portion, about three quarters of an inch in length, is flattened 

 and oval in shape, and occupies the lachrymal fossa in the orbital 

 plate of the frontal bone. It is in contact superiorly with the perios- 

 teum, with which it is closely connected by its upper and convex 

 surface ; by its inferior or concave surface it is in relation with the 

 globe of the eye, and the superior and external rectus ; and by its 

 anterior border with the broad tarsal ligament. By its posterior 

 border it receives its vessels and nerves. The palpebral portion, 

 smaller than the preceding, is situated in the upper eyelid, extending 

 downwards to the superior margin of the tarsal cartilage. It is con- 

 tinuous with the orbital portion above, and is enclosed in an invest- 

 ment of dense fibrous membrane. The secretion of the lachrymal 

 gland is conveyed away by ten or twelve small ducts which run for a 

 short distance beneath the conjunctiva, and open upon its surface by a 

 series of pores about one-twentieth of an inch apart, situated in a 

 curved line a little above the upper border of the tarsal cartilage. 



Lachrymal canals. The lachrymal canals commence at the minute 

 openings, puncta lachrymalia, seen upon the lachrymal papillae of the 

 lids at the outer extremity of the lacus lachrymalis, and proceed in- 



