FACE AND FRONTAL REGION OF HEAD 5 



anterior aspect of the eyeball. At the margins of the lids it 

 is continuous with the skin, whilst, through the puncta lacri- 

 malia and the lacrimal ducts, it becomes continuous with 

 the lining membrane of the lacrimal sac. The line of re- 

 flection of the conjunctiva from each of the eyelids on to the 

 eyeball is termed a fornix conjunctiva. Owing to the greater 

 vertical extent of the upper lid, the conjunctival recess 

 between the upper lid and the eyeball is larger than that 

 behind the lower lid. The conjunctiva is loosely connected 

 with the eyelids on the one hand, and with the sclera, or- 

 white part of the eyeball, on the other. Over the cornea the 

 membrane becomes thinned down to a mere epithelial cover- 

 ing, which forms the epithelium of the cornea. 



In connection with the conjunctiva, the plica semilunaris 

 and the caruncula lacrimalis must be examined. The 

 caruncula is the reddish, fleshy -looking elevation which 

 occupies the centre of the lacus lacrimalis. From its surface 

 a few minute hairs project. The plica semilunaris is of interest 

 because it is the rudimentary representative, in the human eye, 

 of the membrana nictitans, or third eyelid, found in many 

 animals. It is a small vertical fold of conjunctiva, which is 

 placed immediately to the lateral side of the caruncula, and it 

 slightly overlaps the eyeball at that point (Fig. i). 



Dissection. Distend the eyelids slightly by placing a little 

 tow or cotton wool, steeped in preservative solution, in the con- 

 junctival sac ; then stitch the margins of the lids together. 

 Distend the cheeks and lips slightly by placing tow or cotton 

 wool, steeped in preservative solution, in the vestibule of the 

 mouth that is, between the cheeks and lips externally and the 

 teeth and gums internally ; then stitch the red margins of the 

 lips together. 



Reflect the skin by means of three incisions, a median longi- 

 tudinal and two transverse. Commence the median incision 

 midway between the root of the nose and the external occipital 

 protuberance, carry it forwards to the forehead and then down- 

 wards along the median line of the forehead, the nose and the 

 lips, to the tip of the chin. Commence the upper horizontal 

 incision at the level of the rima palpebrarum ; carry it laterally 

 from the longitudinal incision to the medial commissure, then 

 round the margins of the rima to the lateral commissure, and, 

 finally, backwards to the ear. The lower horizontal incision 

 should run from the angle of the mouth to the posterior border 

 of the ramus of the mandible. Reflect the upper and middle 

 flaps and leave them attached posteriorly. Reflect the lower 

 flap downwards to the lower border of the mandible. Note, 

 whilst reflecting the skin, that many of the superficial fibres of 

 the facial muscles are implanted into its deep surface. It is 



