Conjunctiva 73 



finger over the outer end of the lids and then cause the orbicularis to 

 contract, the inward sweeping action of the muscle is manifest.) 



It is supplied by the facial nerve. 



The tendo oculi is for mooring the inner ends of the tarsal 

 cartilages. It is attached to the nasal process of the superior maxilla 

 anterior to the lachrymal groove, and passes outwards over the front of 

 the lachrymal sac, giving accessory fibres to the sac. It can easily be 

 felt when the lids are firmly drawn outwards ; the sac should always 

 be opened by incising just below the tendon. 



Blepbaro-spasm (/SAe^apo, eyelids] is spasmodic contraction of 

 the orbicularis ; it may be caused by a piece of grit lodged under the 

 eyelid, in which case a sensory impulse is sent by a twig of the fifth 

 nerve upon the conjunctiva, which returns from the brain as a reflex 

 stimulus by palpebral twigs of the seventh ; or it may be caused by 

 conjunctivitis. When the spasm is inveterate, as it is apt to be in 

 strumous ophthalmia, it may be expedient to sevey the elliptical fibres 

 at the outer commissure. 



As a result of blepharo-spasm, the free borders of the lids may be 

 ' turned inwards,' entropion (ei>, in ; rporrrj, turn), against the front of the 

 eye-ball, so that the eyelashes irritate the cornea. This complication 

 is called trichiasis (0pi, rpi/cos-, hair), and may demand not only the re- 

 moval of the eyelashes, but even some operation devised to everting the 

 edge, for producing, in fact, an artificial ectrophtm (e|, outwards, and 

 Tponr)) or eversion of the lids. It may be due to the contraction of 

 a scar of the face, to paralysis of the orbicularis, or to the weakness 

 of the muscle which is often found in old persons. 



The levator palpebrae superioris arises just above the optic 

 foramen, and runs forwards beneath the roof of the orbit and the 

 frontal nerve, and above the superior rectus, to be inserted into the 

 front of the cartilaginous foundation of the upper lid. 



It is supplied by the third nerve. The muscle is, as its name 

 implies, the opponent of the orbicularis palpebrarum, which is the 

 sphincter of the lids. It is supplied by the third nerve, and the lid con- 

 sequently droops, ptosis (TTTWO-IS, falling), when that nerve is paralysed. 



On the posterior surface of the lids is the delicate mucous membrane, 

 the conjunctiva, which, reflected thence over the front of the eye-ball, 

 'joins together' the eyelids and the sclerotic. Like other mucous 

 membranes, it consists of a basement membrane, with vessels, nerves, 

 and connective tissue beneath it, and with epithelium on the free 

 surface. 



The epithelium is for the most part columnar, but it gradually 

 becomes squamous as it approaches the free border of the lids. Over 

 the front of the cornea the conjunctiva is represented only by the layers 

 of epithelial cells, the most superficial of which are stratified. 



Where it lines the lids it is thick and vascular, and is studded with 

 papillae, which, under the influence of chronic inflammation, become 



