504 MEIBOMIAN GLANDS. CONJUNCTIVA. 



The Inferior fibre-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 cartilage. 

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

 canthus the tarsal cartilages terminate at the commencement of the 

 lacus lachrymalis, and are attached to the margin of the orbit by the 

 tendo oculi. At their outer extremity they terminate at a short dis- 

 tance 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 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 ; 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. 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 palpe- 

 bral 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 vessels can be traced into it. Upon the sclerotica it 

 is thicker and less adherent, but upon the inner surface of the lids is 

 very closely connected, and is exceedingly vascular. It is continuous 

 with the general gastro-pulmonary 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 



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



