82 



LACRYMAL ORGANS, 



and from the lower edge of the palpebral ten- 

 don, curving at first downwards and outwards, 

 then upwards and outwards, within the lower 

 eyelid and along the edge of the orbit, extend- 

 ing some way down over the cheek. The part 

 of the orbicularis more immediately contained 

 within the eyelids, sometimes called the palpe- 

 bral and ciliary portions, in contradistinction to 

 the outermost fibres, which are without the eye- 

 lids, and encircle the base of the orbit, therefore 

 called the orbital portion, consists of pale thin 

 fibres, of which those at the margin of the eye- 

 lids are collected into a considerable fasciculus, 

 having interposed between them and the tarsal 

 cartilage the roots of the cilia. At the outer 

 canthus the upper and lower fibres intercross 

 and adhere to the external palpebral ligament. 

 That many of the fibres of the orbicularis are 

 inserted into and exert their action in a great 

 degree on the skin of the eyelids, may be easily 

 ascertained in the living person, by observing, 

 during the action of closing the eye, the traction 

 of the skin of the eyelids towards the nasal can- 

 thus. By this traction, the skin, especially in 

 the lower eyelid, is very much corrugated. This 

 corrugation of the skin of the lower eyelid by 

 the action of the orbicularis is greatest right 

 over the lower part of the lacrymal sac, that 

 part which we commonly press upon when we 

 want to evacuate any accumulation of mucus or 

 tears, that part where abscess of the sac gene- 

 rally bursts and leaves a fistulous opening, 

 that part which we open in the operation for so- 

 called fistula lacrymalis. This part of the 

 lacrymal sac must therefore be immediately 

 affected by the contraction of the muscle, and 

 the pressure thus produced, together with that 

 on the upper blind end of the sac by the supe- 

 rior fibres, will promote the transmission of the 

 tears and conjunct! val mucus into the nasal 

 duct. 



The great use of the orbicularis palpebrarum 

 is to close the eyelids; but in effecting this it 

 acts at a disadvantage, inasmuch as its action 

 on the eyelids is not direct, but oblique ; there- 

 fore they are brought together only by being 

 drawn horizontally inwards, though it is the 

 lower eyelid alone which yields to this latter 

 movement. We may imitate in some degree 

 the mode of action of the orbicularis, but in an 

 opposite direction, by pressing the skin imme- 

 diately outside the outer canthus, towards the 

 temple. 



Levator pulpebra superioris muscle. This is 

 the antagonist of the upper part of the orbicu- 

 laris. It is a weak slender muscle, but then it 

 has the advantage of exerting its action in a di- 

 rect manner. It extends from the bottom of the 

 orbit to the superior tarsal cartilage, lying im- 

 mediately underneath the roof of the orbit. It 

 is the longest of all the muscles of the orbit. 

 Thin and triangular, it rises by its apex, which 

 is a short tendon, from the upper edge of the 

 optic foramen. The fleshy body of the muscle 

 gradually increases in breadth as it proceeds 

 forwards ; then bending downwards over the 

 eyeball, its insertion takes place by a broad thin 

 tendinous expansion, the base of the triangle, 

 into the upper margin and anterior surface of 



the superior tarsal cartilage, being incorporated 

 at the same time with the so-called tarsal liga- 

 ment. It is by the action of this muscle that 

 the upper eyelid is drawn up and retracted 

 within the orbit. 



Having thus described the skeleton and mus- 

 cles of the eyelids, it remains to consider their 

 investments and appendages. The investment 

 of their inner surface, the palpebral conjunctiva, 

 will be described farther on, along with the 

 rest of the conjunctiva. The skin of the eyelids 

 lies over the fibres of the orbicularis palpebra- 

 rum. It is very fine and destitute of hairs, but 

 contains minute sebaceous follicles. The latter 

 are sometimes, especially in the lower eyelid, 

 enlarged, and give out a morbid secretion, which 

 is hard, and forms those horny excrescences 

 occasionally met with in old persons. 



Cellular tissue of the eyelids. The conjunc- 

 tiva investing the inner surface of the tarsal car- 

 tilages adheres without the intermedium of any 

 cellular tissue. The connection between the 

 two structures is immediate and intimate, as in 

 the compound membranes called fibro-mucous. 

 The rest of the palpebral conjunctiva adheres 

 by cellular tissue. The palpebral and ciliary 

 portions of the orbicularis muscle are connected 

 on the one hand to the tarsal cartilages and 

 other subjacent parts, and on the other to the 

 superjacent skin, by a laminar cellular tissue, 

 which, like that in some other parts of the 

 body, is not combined with the adipose tissue. 

 Being rather loose, the cellular tissue of the 

 eyelids becomes readily infiltrated by effused 

 fluids, as in (edema and emphysema. It is not 

 unfrequently the seat of abscess. 



Roots of the eyelashes. From the anterior 

 edge of the free margins of the eyelids, the 

 eyelashes spring. They are inserted three or 

 four deep, especially in the middle. The cap- 

 sules of the bulbs of the eyelashes lie close on 

 the tarsal cartilage under the ciliaris muscle and 

 skin, extending to the depth of about one- 

 eighth of an inch. One of the operations for 

 trichiasis is to extirpate the roots of the eye- 

 lashes, but it is very difficult to remove them 

 all, the oozing of blood is generally so great. 

 When the part has healed after the operation, 

 and the case seems doing well, a hair or two 

 will often be found here and there sprouting 

 out again. 



Connected with the roots of the eyelashes, 

 as with other hairs, are small sebaceous glands, 

 consisting of minute but distinct lobules or 

 grains closely surrounding the capsule, into 

 which they send one or more excretory ducts.* 



Meibomian glands. Glandulce Meibo- 

 mianee s. palpebrarum &ebace<e ; Fr. Les 

 glandes de Meibom ; Ital. Le glandule Mei- 

 bomiane ; -Germ. Die Meibomschen Drusen. 



* Gurlt, Vergleichende Untersuchungen liber die 

 Haul des Menschen und der Haussaugethiere, 

 besonders in Beziehung auf die Absonderungsorgane 

 des Haut-talges und des Schweisses. In Mliller's 

 Archiv, 1835, p. 399. 



t Zeiss. Fortgesetzte Unteisuchungen liber die 

 Anatomie und Pathologic der Augenlider von Dr. 

 B. Zeiss in Dresden. In Ammon's Zeitschrift, &c. 

 B. 5, p. 216. 



