TAltSI MEIUOMIA3V GLANDS. 447 



lachrymalis upon each of the two lids is a small angular projection, 

 the lachrymal papilla or tubercle ; and at the apex of each papilla is 

 a small orifice (punctum lachrymale), the commencement of the 

 lachrymal canal. 



The eyelids have, entering into their structure, in tegument, orbicu- 

 laris muscle, tarsal cartilages, Meibomian glands, and conjunctiva. 



The tegumentary cellular tissue of the eyelids is remarkable for 

 its looseness and for the entire absence of adipose substance. It is 

 particularly liable to serous infiltration. The fibres of the orbicu- 

 laris muscle covering the eyelids, are extremely thin and pale. 



The Tarsal cartilages are two thin lamellae of fibro-cartilage 

 about an inch in length, which give form and support to the eyelids. 

 The superior is of a semilunar form, about one-third of an inch in 

 breadth at its middle, and tapering to each extremity. Its lower 

 border is broad and flat, its upper is thin, and gives attachment to 

 the levator palpebrsc and to the fibrous membrane of the lids. 



The Inferior fibro-cartilage is an elliptical band, narrower than the 

 superior, and situated in the substance of the lower lid. Its upper 

 border is flat, and corresponds with the flat edge of the upper car- 

 tilage. The lower is held in its place by the fibrous membrane. 

 At the inner canthus the tarsal cartilages terminate at the com- 

 mencement of the lachrymalis, and are attached to the margin of 

 the orbit by the tendo oculi. At their outer extremity they termi- 

 nate at a short distance from the angle of the canthus, and are 

 retained in their position by means of a decussation of the fibrous 

 structure of the broad tarsal ligament, called the external palpebral 

 ligament. 



The Fibrous membrane of the lids is firmly attached to the perios- 

 teum, around the margin of the orbit, by its circumference, and to 

 the tarsal cartilages by its central margin. It is thick and dense on 

 the outer half of the orbit, but becomes thin to its inner side. Its 

 use is to retain the tarsal cartilages in their place, and give support 

 to the lids ; hence it has been named the broad tarsal ligament. 



The Meibomian glands* are embedded in the internal surface of 

 the cartilages, and are very distinctly seen on examining the inner 

 surface of the lids. They have the appearance of parallel strings 

 of pearls, about thirty in number in the upper cartilage, and some- 

 what fewer in the lower ; they open by minute foramina upon the 

 edges of the lids. They correspond in length with the breadth of 

 the cartilage, and are consequently longer in the upper than in the 

 lower lid. 



Each gland consists of a single lengthened follicle or tube, into 

 which a number of small clustered follicles open ; the latter are so 

 numerous as almost to conceal the tube by which the secretion is 

 poured out upon the margin of the lids. They are figured, after 

 a very careful examination," in Dr. Quain's " Elements of Anatomy." 



* Henry Mcibomius, " de Vasis Palpebrarum Novis," 1666. 



