Ii88 A MANUAL OF ANATOMY 



devoid of fat. The palpebral fibres of the orbicularis palpebrarum 



form a very delicate, pale sheet. The tarsal plate, or tarsus, one 

 for each eyelid, is a fibrous plate, and is composed of compact 

 fibrous tissue. The superior tarsal plate is larger than the inferior, 

 and is semilunar, its depth at the centre being about I inch. Its 

 upper and anterior part gives insertion to the levator palpebrae 

 superioris. The inferior tarsal plate is narrow, and is almost 

 of the same depth throughout. The ciliary margins of the tarsal 

 plates are free, straight, and comparatively thick. The orbital 

 margins are attached to the circumference of the orbit by mem- 

 branous expansions, called the superior and inferior palpebral 

 ligaments. The superior palpebral ligament is attached above 

 to the upper part of the circumference of the orbit, where it 

 blends with the periosteum, and below it blends with the tendon 

 of insertion of the levator palpebrae superioris on the superior 

 tarsal plate. The inferior palpebral ligament extends between the 

 lower part of the circumference of the orbit and the lower margin 

 of the inferior tarsal plate. The superior and inferior palpebral 

 ligaments together constitute a partition, called the septum orbitale, 

 which intervenes between the superficial and deep palpebral 

 structures. 



Externally and internally the tarsal plates have attachments by 

 means of the tarsal ligaments, which are two in number, external 

 and internal. The external tarsal ligament is formed by the junction 

 of the superior and inferior palpebral ligaments, and is attached to 

 the malar bone. The internal tarsal ligament, tendo palpebrarum, 

 or tendo oeuli, is independent of the palpebral ligaments. Internally 

 it is attached to the external surface of the nasal process of the 

 superior maxilla in front of the lachrymal groove. From this 

 point it passes horizontally outwards for about ^ inch, and then 

 divides into two laminae, which are attached to the superior and 

 inferior tarsal plates. It passes in front of the lachrymal sac, 

 and furnishes an offset, which passes behind the sac to be attached 

 to the lachrymal crest of the lachrymal bone. The ligament gives 

 origin to a few fibres of the orbicularis palpebrarum. 



The Meibomian glands are situated on the internal surface of 

 each tarsal plate, and lie between the plate and the conjunctiva at 

 right angles to the ciliary margin. There are about thirty in the 

 upper eyelid, and about twenty in the lower, and they are arranged 

 in parallel rows, which occupy grooves on the ocular surface of each 

 tarsal plate. Each gland opens by an independent orifice, and these 

 orifices are arranged in a single row, lying a little behind the ciliary 

 margin of the eyelid. 



Structure. — The Meibomian glands are sebaceous glands, and their secretion 

 lubricates the margins of the eyelids, and prevents them from adhering. 

 Each consists of a tube, closed at one end, aiad having its sides beset with 

 diverticula. The wall of the tube is composed of a basement membrane, 

 which is lined with cubical epitlielium throughout the greater part of the 

 gland, but close to the orifice this is replaced by stratified epithelium. 



