238 THE POCKET ANATOMY 



in shape, the lower a narrow oblong strip. In their substance 

 are lodged the Meibomian follicles. Each tarsal plate is 

 at its edge (except towards the ocular fissure, where it is 

 free) continuous with the membranous sheet known as the 

 palpebral ligament, while internally and externally it receives 

 the tarsal ligaments (p. 22). The superior tarsal plate re- 

 ceives above the main insertion of the levator palpebrse 

 superioris. 



The palpebral ligaments form an incomplete diaphragm 

 for the anterior orifice of the orbit ; peripherally they are 

 attached to orbital margin and centrally to edge of tarsal 

 plates. 



The conjunctiva is the membrane which forms the most 

 posterior layer of both eye-lids, at the free edges of which 

 it joins the skin. At the base of each eye-lid, where the 

 structures enter its layers, the conjunctiva is reflected on 

 to the eye-ball, the lines of reflection being known as the 

 fomices, of which the superior is the deeper ; into it some 

 fibres of the levator palpebrae superioris are inserted. Over 

 the eye-ball, where it covers the sclerotic, the conjunctiva is 

 loosely connected, some connective-tissue and Tenon's capsule 

 intervening ; but at the corneo-sclerotic margin the conjunctiva 

 is firmly adherent, covering the cornea as its anterior epithelial 

 layer. The conjunctival sac has opening into it above the 

 ducts of the lachrymal gland, and below the openings of the 

 lachrymal canaliculi at the puncta lachrymalia. 



The lachrymal gland occupies a depression in the supero- 

 external angle of the orbit ; the anterior margin is connected 

 to the back part of the upper eye-lid. The ducts (12 or 14) 

 open by apertures, placed in a row, on the inner surface of 

 the upper lid. 



The lachrymal canals commence at the puncta lachrymalia, 

 which are the openings of the canaliculi, and, arching in the 

 free edge of the lid, pass inwards to open into the lachrymal 

 sac. 



The lachrymal sac is placed in a groove formed by the 

 lachrymal bone and the nasal process of the superior maxilla, 

 being behind the tendo oculi, and in front of the tensor tarsi ; 

 it is the dilated upper end of the nasal duct. 



The nasal duct, formed by the lachrymal, superior maxilla 

 and inferior turbinal bones, leads from the lachrymal sac to 

 the inferior meatus of the nose, where it opens, the aperture 

 being partly guarded by a valve formed of the mucous mem- 

 brane. It is about inch long, and is directed downwards, 

 and slightly outwards and backwards. 



