The canaliculi are immediately surrounded by the fibres of the internal palpebral ligament, and those of the tensor tarsi muscle.
Lacrymal sac ; saccus lacrymalis ; Fr., Le sac lacrymal; Ital. II sacco lagrimale; Germ., Der Thriinensack.—( Fig. 16). This is a membra neous reservoir of a vertically elongated form, and externally compressed, nine-twentieths of an inch long, and two-tenths broad externally.
margin of each eyelid, where the fissure of the nasal canthus begins, there has been already de scribed a small papillary eminence, lacrymal papilla, papilla lacrymalis, in the summit of which is a small orifice, lacrymal point, of such a size as to admit a thick bristle. The lacrymal points, puncta lacrymalia ; Fr. Les points lacrymaux ; Ital. I punti lagrimali ; Germ. Die Thriinenpunkten ; are from their size and situation sufficiently conspicuous as not to be confounded with one of the orifices of the Meibomian follicles. In the natural state the lacrymal papillm are inclined towards the lacus lacrymalis. The lower papilla is somewhat more prominent than the upper, and situate some what more towards the temple. The lacrymal Here it is seen that the nasal duct is much broader viewed from the side than from before. a, b, superior and inferior lacrymal canaliculi ; c, d, lacrymal sac ; e, f, nasal duct ; f, nasal orifice of the nasal duct, seen quite in its natural state.
It lies, by its inner and posterior surface, in the lacrynial 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,—finis circus 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 nasalis ; Fr., Le canal nasal; Ital., 11 condotto nasale ; Germ., Der Nasenkanal, 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. I t ru ns 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.