THK LACHRYMAL AI'l'ARATUS 1017 



THE l,\( HHVMAI. AlM'AH A i 



The tears are secreted by ;ni acinous gland, and flow through line ducts to the 

 upper outer part of the conjunct ival sac. whence they are drained off through the 

 puncia. pass along the canaliculi into the lachrymal sac, and ultimately run down 

 the nasal duct to gain t lie inferior nicaliis ot t he iin-v. 



The lachrymal gland is situated near the front of the outer part of the roof of 

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

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

 expansion of the levator pal|H-l>ra> sujK-rioris, but small gaps in the expansion ]HT- 

 init of connections between these two parts of the gland. The up|x r and larger 

 subdivision (xn/itrinr lurliri/nnil i/lunil) is a firm elongated body, about the si/.e of 

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

 lobules. The upper surface (ne\t tin- orbital roof) is convex, and its lower surface 

 is slightly concave. Anteriorly, the gland almost reacht s the upper orbital mar- 

 gin, and it extends backwards for approximately one-fourth the depth of the 

 orbit, measuring about twelve millimetres in this direction. The outer border of 

 the gland descends to near the insertion of the fascia! expansion of the external 

 rectus, while its inner border almost reaches the outer 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 inner border from 

 the orbital margin (suspensory ligament of the gland). 



FIG. 744. LACHRYMAL APPARATUS. (After Schwalbe.) 



UPPER EYELID PARTIALLY DIVESTED OF 



SUN 

 SUPERIOR LACHRYMAL GLAND 



INFERIOR LACHRYMAL GLAND -j&jgiK?' ~SJ^^^ ^ UPPER PUHCTUM 



. LACHRYMAL SAC, NEAR ITS FUNGUS 



_ . COMMON DUCT FORMED BY JUNCTION 

 DUCT FROM SUPERIOR GLNO ' ~*~1(B OF DUCTUS 



UPPER AND LOWER OUCTUS 



LOWER PUNCTUM 

 NASO-LACHRYMAL DUCT 



The lower subdivision of the gland (inferior lachrymal gland) is composed of 

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

 conjunctiva! fornix, reaching out wards as far as the external canthus. 



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

 on the outer part of the upper fornix conjunctiva, 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 outermost duct is the largest, and 

 opens at the level of the external canthus. 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 inner canthus are the two puncta lachrymalia, upper and lower, each 

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

 towards the conjunctiva! sac. so that the puncta are well adapted for their function 

 of draining off any fluid collecting there. 



The ductus (canaliculi) lachrymales extend from the punrta to the lachrymal 

 sac. The lumen at the punctum is horizontally oval, from its lips being slightly 

 compressed 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 inner 

 canthus than the upper, the corresponding canalicuJus is longer. 



On tracing either ductus from its origin, we h'nd that at first it runs nearly 

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

 courses more or less horizontally, converging slightly towards its fellow, and not 

 infrequently joining it before owning into the sac. The calibre varies considerably 



