1118 



THE ORGANS OF SPECIAL SENSE 



to the back part of the upper eyelid, where it is covered to a slight extent by the 

 reflection of the conjunctiva. The fore part of the gland is separated from the 

 rest by a fibrous septum; hence it is sometimes described as a separate lobe, 

 called the inferior lacrimal gland (glandula lacrimalis inferior}, the back part of 

 the gland then being called the superior lacrimal gland (glandula lacrimalis superior}. 

 The ducts of the lacrimal gland, from six to twelve in number, run obliquely 

 beneath the mucous membrane for a short distance, and, separating from each 

 other, open by a series of minute orifices on the upper and outer half of the con- 

 jiinpfiva near its reflection on to the globe. These orifices are arranged in a row, 

 so as to disperse the secretion over the surface of the membrane. 



Puncta 

 lacrimalia. 



Fio. 826. The Meibomian glands, etc., seen from the inner surface of the eyelids. 



Structure. In structure and general appearance the lacrimal resembles the serous salivary 

 glands. In the recent state the cells are so crowded with granules that their limits can hardly 

 be defined. Each cell contains an oval nucleus, and the cell protoplasm is finely fibrillated. 



The Lacrimal Canals (Fig. 828) commence at the minute orifices, puncta lacri- 

 malia, on the summit of small conical elevations, the lacrimal papillae (papillae 

 lacrimalis}, seen on the margin of the lids at the outer extremity of the lacus 

 lacrimalis. The superior canal (ductus lacrimalis superior}, the smaller and shorter 



of the two, at first ascends, and then bends at an 

 acute angle, and passes inward and downward to 

 the ampulla of the lacrimal sac. The inferior 

 canal (ductus lacrimalis inferior] at first descends, 

 and then passes almost horizontally inward to the 

 ampulla. These canals are dense and elastic in 

 structure and somewhat dilated at their angles. 

 The mucous membrane is covered with stratified 

 epithelium upon a basement membrane. Outside 

 FIG. 827. Alveoli of lacrimal gland, the latter is a layer of striped muscle continuous 



with the Tensor tarsi. The two canals join in a 



dilatation, the ampulla (ampulla ductus lacrimalis), which empties into the 

 lacrimal sac. 



The Lacrimal Sac (saccus lacrimalis) (Fig. 828) is the upper dilated extremity 

 of the nasal duct, and is InHgpr] i n a deep p-roove formed by the lacrimal bone and 

 the nasal process of the maxilla bone. It is oval in form, its upper extremity 

 being closed in and rounded, while below it is continued into the nasal duct. 

 It is covered by a fibrous expansion derived from the tendo oculi, and on its deep 



