92 



LACRYMAL ORGANS. 



It lies, by its inner and posterior surface, in 

 the lacrymal groove, with the periosteum 

 of which it is closely incorporated. Its an- 

 terior and outer surface, which lies without 

 the groove, is immediately covered by a 

 strong aponeurosis derived from the upper 

 and lower edge of the horizontal tendon of the 

 orbicularis muscle, which passes across the la- 

 crymal sac a little above the centre. This apo- 

 neurosis adheres to the margins of the bony 

 groove in which the sac is lodged, and there 

 becomes continuous with the periosteum. More 

 superficially, the anterior and outer surface is 

 covered by the muscular fibres of the orbicu- 

 laris and by the skin. 



Above the lacrymal sac forms a cul-de-sac or 

 blind end, -Jlnis cacus sacci lacrymalis. Be- 

 low it passes into the nasal duct. This transi- 

 tion is marked by a slight contraction, some- 

 times inside, by a circular fold of the mucous 

 membrane, of which both are formed. 



At its anterior and outer part, a little below 

 its upper blind end, and immediately behind 

 the internal palpebral ligament, the lacrymal 

 sac receives the canalicules. Overhanging the 

 orifices of these there is a small semilunar fold 

 of the mucous membrane of the sac.* 



The nasal duct ; ductus nasulis ; Fr., Le 

 canal nasal ; Ital., II condotto Jiusule ; Germ., 

 Der Nasenkunal, is a laterally compressed 

 canal, about three-quarters of an inch in length, 

 and readily admitting the passage of a probe 

 the fifteenth of an inch thick, continued from the 

 lower part of the lacrymal sac. Itruns downwards, 

 backwards, and a little outwards in the osseous 

 canal already described, of which it is indeed 

 nothing but the membraneous lining. The 

 nasal duct is more contracted in its middle than 

 at either extremity. It opens in the anterior 

 and upper part of the lower meatus, at the 

 lateral wall of the nasal cavity, and about one 

 inch from the entrance of the nostril. Its ori- 

 fice, which is overhung by the lower spongy 

 bone, is a long fissure, oblique from above 

 downwards and from within outwards. The 

 obliquity of the orifice of the nasal duct is 

 owing to the circumstance that the posterior or 

 external wall of the membraneous part of the 

 nasal duct descends farther than the osseous 

 canal, and forms, by means of the folded pitui- 

 tary membrane, a semi-canal, which descends 

 in the external wall of the lower meatus, whilst 

 the internal wall of the membraneous part of the 

 nasal duct is shorter, and terminates where the 

 osseous canal stops. 



The lacrymal sac and nasal duct are com- 

 posed of a thick soft mucous membrane, which 

 must be considered as productive of that of the 

 nose. Externally, this mucous membrane is 

 united with the periosteum of the osseous sur- 

 faces in connection with the lacrymal sac and 

 nasal duct, and as far as concerns that part of 

 the lacrymal sac not in the osseous groove, by 

 the aponeurosis derived from the tendo palpe- 

 brarum. 



Internally, the mucous membrane of the la- 

 crymal sac and nasal duct forms various small 



* Rosenmiiller, op. cit. 125. 



plicae or ruga?. Red and villous, it is quite 

 different from the white and smooth mucous 

 membrane of the canalicules. Like the pitui- 

 tary membrane of the nose, it secretes, in the 

 healthy state, a clear, mild, fluid mucus. 



Lacrymal or tensor tarsi muscle. Here is 

 perhaps the proper place to notice a muscle 

 which was discovered many years ago by M. 

 Duverney,* delineated and described by Rosen- 

 miiller f in 1805, and more recently re-described 

 by Dr. Homer, J an American anatomist, with 

 whose name it is now commonly associated. 



To get a view of this muscle, Professor Hor- 

 ner directs us to cut through the eyelids and 

 separate them from the ball, except at the inner 

 canthus ; then turn the lids over the nose, re- 

 move the semilunar fold and the conjunctiva in 

 the neighbourhood, with the fatty matter, when 

 the muscle, such as it is represented in the fol- 

 lowing description, will be seen. 



" The tensor tarsi arises from the posterior 

 superior part of the os unguis, just in advance 

 of the vertical suture between the os planum and 

 the os unguis. Having advanced three lines, it 

 bifurcates ; one bifurcation is inserted along 

 the upper lacrymal canalicule, and terminates 

 at its punctum, or near it; and the lower bifur- 

 cation has the same relation to the lower lacry- 

 mal canalicule. The base of the lacrymal 

 caruncle is placed in the angle of the bifurcation. 

 The superior and the inferior margins of the 

 muscle touch the corresponding fibres of the 

 orbicularis palpebrarum, where the latter is 

 connected with the margin of the internal can- 

 thus of the eye, but may be readily distin- 

 guished by their horizontal course. The nasal 

 face of this muscle adheres very closely to that 

 portion of the sac which it covers, and also to 

 the lacrymal canalicules. The lacrymal sac 

 rises about a line above its superior margin, and 

 extends in the orbit four lines below its inferior 

 margin. The orbital face of the muscle is 

 covered by a lamina of cellular membrane, and 

 between this lamina and the ball of the eye are 

 placed the semilunar fold of the conjunctiva, 

 and a considerable quantity of adipose matter. 

 As the bifurcated extremities of the muscle fol- 

 low the course of the canalicules, they are co- 

 vered by the conjunctiva. The muscle is an 

 oblong body, half an inch in length, and about 

 one quarter wide, bifurcated at one end ; and it 

 arises much deeper from the orbit than any ac- 

 knowledged origin of the orbicularis. The su- 



* (Euvres Anatomiques de M. Duverney, tom. ii. 

 4to., Paris, 1761. -After speaking of the fibres of 

 the orbicularis which lie over the lacrymal sac, it is 

 said (tom. i. p. 130), " Entre ces fibres, il y a un 

 petit muscle an dedans du grand angle qui prend 

 son origine de la partie anterieure de 1'os planum 

 et s'insere a la partie interne du tendon mitoyen on 

 commun a 1'appose de 1'orbiculaire ; c'est un petit 

 muscle que j'ai observe il y a long-temps." 



f Rosenmiiller, Icones Chirurgico-Anatomicae. 

 Wiemar, 1805. See also Mackenzie in Medical 

 Gazette, vol. xi. 



i Medical Repository for July, 1822. See also, 

 A Treatise on Special and General Anatomy, by 

 William E. Homer, M. D., Professor of Anatomy 

 in the University of Pennsylvania, &c. vol. ii. p. 

 498. Philadelphia, 1826. 



