LACRIMAL APPARATUS 



1079 



The Lacrimal Apparatus 



The tears are secreted by an acinous gland, and flow through fine ducts to the 

 upper lateral part of the conjunctival sac, whence they pass over the cornea and 

 are drained off through the puncta, pass along the canaliculi into the lacrimal sac, 

 and ultimately down the naso-lacrimal duct to the inferior meatus of the nose. 



The lacrimal gland is situated near the front of the lateral part of the roof of 

 the orbit, tying in a depression in the orbital plate of the frontal bone. It consists 

 of two very unequal parts, one placed above and the other beneath the tendinous 

 expansion of the levator palpebrse superioris, but small gaps in the expansion per- 

 mit of connections between these two parts of the gland. The upper and larger 

 subdivision (superior lacrimal gland) is a firm elongated body, about the size of 

 a small almond; it has a greyish-red colour, and is made up of closely aggregated 

 lobules. The upper surface (next the orbital roof) is convex, and its lower surface 

 is slightly concave. 



Anteriorly, the gland almost reaches the upper orbital margin, and it extends backward 

 for approximately one-fourth the depth of the orbit, measuring about twelve millimetres in 

 this direction. The lateral border of the gland descends to near the insertion of the fascial 

 expansion of the lateral rectus, while its medial border almost reaches the lateral edge of the 

 superior rectus; its transverse measurement is about twenty millimetres. It is enveloped in a 

 capsule, which is slung by strong fibrous bands passing to its medial border from the orbital 

 margin (suspensory ligament of the gland). 



Fig. 822, — Dissection of the Eye to Show the Lacrimal Apparatus, Anterior View. 



Palpebra superior 



Inferior lacrimal gland 

 Excretory ducts j 

 Superior lacrimal gland j ' 



Tendon of superior oblique 

 I Superior lacrimal duct 



/ Lacus lacrimalis 



J Medial palpebral commissure 



. -^^P^ -'j Fornix of lacrimal sac 



-^^ - - Junction of lacrimal ducts 



- - Inferior lacrimal duct 



- Nasolacrimal duct 



" ■ - I r Lacrimal papilla and punctum 



Inferior oblique 

 Palpebra inferior 



The lower subdivision of the gland {inferior lacrimal gland) is composed of 

 loosely applied lobules, and lies immediately over the lateral third of the upper 

 conjunctival fornix, reaching lateralwarcl as far as the lateral angle. 



Each subdivision of the gland possesses several excretory ducts, which all open 

 on the lateral part of the upper fornix conjunctivse, about four millimetres above 

 the upper border of the tarsus. Those of the superior gland, three or four in 

 number, pass between the lobules of the lower gland; the most lateral duct is the 

 largest, and opens at the level of the lateral angle of the eye. The ducts of the 

 inferior gland in part discharge themselves into those of the upper, but there are 

 also several fine ducts from this subdivision that run an independent course. 



Near the medial angle are the two puncta lacrimalia, upper and lower, each 

 situated at the summit of its papilla. The top of each papilla curves backward 

 toward the conjunctival sac, so that the puncta are well adapted for their function 

 of draining off any fluid collecting there. 



The ductus (canaliculi) lacrimales extend from the puncta to the lacrimal sac. 

 The lumen at the punctum is horizontally oval, from its lips being slightly com- 

 pressed antero-posteriorly ; the lumen of the lower punctum is somewhat larger 

 than that of the upper. As the lower papilla is a little further from the medial 

 angle of the eye than the upper, the corresponding canaliculus is longer. 



On tracing either ductus from its origin, we find that at first it runs nearly 

 vertically for a short distance, then bends sharply toward the nose, and finally 



