THE EYELIDS. 



The palpebral fascm (septum orbitale) is a fibrous membrane placed beneath the 

 orbicularis muscle, attached on the one hand to the margin of the orbit, and on the 

 other prolonged towards the attached border of each tarsus. In the lower lid its 

 tissue is continuous with that of the tarsus, but in the upper lid it blends with the 

 tendon of the levator palpebrse. The membrane is thicker at the outer part of the 

 orbit, where it forms the lateral (outer) palpebral or tarsal ligament (figs. 4, 12). 

 The mesial (internal) palpebral ligament, to which the fibres of the orbicularis 

 palpebrarum are attached (see Vol. II. p. 281), is not formed from the general 

 palpebral fascia, but lies altogether in front of it (fig. 4). The palpebral fascia 



Fig. 2. VERTICAL SECTION THROUGH THE UPPER 

 KYKUD, HUMAN (after Waldeyer). Mag- 

 nified. 



a, skin ; l>, orbicularis ; l>', ciliary bundle ; 

 c, involuntary muscle of eyelid ; d, conjunctiva ; 

 e, tarsus ; /, Meiboniian gland ; y, sebaceous 

 gland near eyelashes, with modified sweat-gland 

 opening with it ; h, eyelashes ; i, small hairs iu 

 outer skin ; j, sweat-glands ; k, posterior tarsal 

 glands. 



extends downwards from the crista 

 lacrimalis posterior, between the osseous 

 boundary of the nasal duct and the 

 origin of the inferior oblique muscle, to 

 reach the lower border of the orbit 

 (Merkel). 



The palpebral fascia thus acts as a 

 kind of fibrous septum between the 

 cutaneous and the conjunctival parts 

 of the eyelid at its attached border : it 

 was therefore termed the septum or- 

 bitale by Heiile. It is perforated above 

 the internal tarsal ligament by the 

 termination of the ophthalmic artery, 

 with a considerable anastomotic vein 

 between the superior ophthalmic and 

 the angular, and its attachment to the 

 supra-orbital margin is interrupted in- 

 ternal to the centre by the passage of 

 the supraorbital nerve (in one or two 

 pieces) with the accompanying artery. 



On the ocular surface of each lid 

 are seen parallel vertical rows of what, 



seen through the conjunctival mucous membrane, look like yellow granules. 

 There are twenty to thirty of these rows in the lower lid, somewhat more in the 

 upper lid ; they are the Meibomian or tarsal glands (fig. 3). These are long 

 sebaceous glands, imbedded in the tarsi ; and they open on the free margin of the 

 lids by minute orifices, generally one for each. The glands consist of nearly straight 

 tubes, closed at the end. with numerous small caecal appendages projecting from the 

 sides. Sometimes, however, they are not straight, but are bent round at the blind 

 end, as is shown in some of those represented in fig. 3. The mouths of the tubes are 

 lined by stratified epithelium continuous with that of the skin ; but the ducts and 

 the glandular recesses have a lining of cubical epithelium filled with the f itty 



B 2 



