454 MEIBOMIAN GLANDS. 



rymahs, and are attached to the margin of the orbit by the tenao oculi. 

 At their outer extremity they terminate at a short distance from the angle 

 of the eanthus, and are retained in their position by means of a decussa- 

 tion 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 periosteum, 

 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 aspect of 

 the lids. They have the appearance of parallel strings of pearls, about 

 thirty in number in the upper cartilage, and somewhat fewer in the lower ; 

 and open by minute foramina on 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. Occasionally an arch is formed between two of them, 

 and produces a very graceful appearance. 



The edges of the eyelids are furnished with a triple row of long thick 

 hairs, which curve upwards from the upper lid, and downwards from the 

 lower, so that they may not interlace with each other in the closure of the 

 eyelids, and prove an impediment to the opening of the eyes. These are 

 the eyelashes (cilia), important organs of defence to the sensitive surface 

 of so delicate an organ as the eye. 



The Conjunctiva is the mucous membrane of the eye. It covers the 

 whole of its anterior surface, and is then reflected upon the lids so as to 

 form their internal layer. The duplicatures formed between the globe of 

 the eye and the lids are called the superior and inferior palpebral sinuses, 

 of which the former is much deeper than the inferior. Where it covers 

 the cornea the conjunctiva is very thin and closely adherent, and no ves- 

 sels can be traced into it. Upon the sclerotica it is thicker and less ad- 

 herent, but upon the inner surface of the lids is very closely connected, 

 and exceedingly vascular. It is continuous with the general gastro-pul- 

 monary mucous membrane and sympathises in its affections, as may be 

 observed in various diseases. From the surface of the eye it may be 

 traced through the lachrymal ducts into 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 lachrymal sac, and thence downwards through 

 the nasal duct into the inferior 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 



* Henry Meibomius, '-de Vasis Palpebrarum Novis," 1GGG. 



