Text-book of ophthalmology / by Ernst Fuchs ; authorized translation from the 12th German edition, completely revised and reset, with numerous additions specially supplied by the author and otherwise much enlarged by Alexander Duane.

  • Ernst Fuchs
Date:
[1924]
Catalogue details

Licence: Public Domain Mark

Credit: Text-book of ophthalmology / by Ernst Fuchs ; authorized translation from the 12th German edition, completely revised and reset, with numerous additions specially supplied by the author and otherwise much enlarged by Alexander Duane. Source: Wellcome Collection.

    28/1032 page 8
    The orbicularis is innervated by the facial nerve, the levator by the oculo-motor, and the two tarsal muscles of Müller by the sympathetic. The ligamentum palpebrale mediale arises from the frontal process of the superior maxilla (F, Fig. 2) and first passes straight outward, skirting the anterior wall of the lacrimal sac (/S'). Then it turns round the anterior and external walls of the lacrimal sac and runs backward to the crista lacrimalis posterior of the lacrimal bone (T). We accordingly distinguish in the internal palpebral ligament two branches, which meet at the point where it begins to turn. The anterior branch (v) is situated directly beneath the skin,.and hence is visible in the living subject; at its point of reflection it gives off a process to the upper and lower tarsus respectively (Fig. 3). The posterior branch (h), which starts from the point of reflection and extends to the crista lacrimalis, can be brought to view only by dissection. The two branches together with the lacrimal bone (T) bound a space, triangular on cross section, in which lies the lacrimal sac, the walls of the latter being united by loose connective tissue with the inner surface of the ligament, into the external surface of the ligament are inserted the fibres of the palpebral portion of the orbicularis. One portion of the fibres of the latter springs from the anterior, an¬ other portion from the posterior branch of the ligament. The latter fibres, whose inser¬ tion is in part continued out beyond the posterior extremity of the ligament upon the inner wall of the orbit, are called the pars lacrimalis musculi orbicularis (or tensor tarsi) or, from their discoverer, Horner’s muscle (H). The insertion of the fibres of the orbic¬ ularis into the internal palpebral ligament is of significance for the conduction of tears. (See § 67). The fibres of the orbicularis fuse with the anterior surface of the tarsus. In the neighborhood of the free borders of the lid there are some bundles which lie near the inner margin of the lid, partly in front of, partly behind the excretory ducts of the Meibomian glar.ds (musculus ciliaris Riolani sive subtarsalis; r, Fig. 1). 4. Tarsus; Glands of Lids.—The tarsus (k, Fig. 1) forms, so to speak, the skeleton of the lid, giving it rigidity of form and affording it firm support. The tarsus of the upper lid is broader (higher) than that of the lower (Fig. 3). In the tarsus are distinguished a free and an attached (convex) border, and also an anterior and a posterior surface. The fibres of the orbicularis (o, Fig. 1) lie upon the anterior surface, while the posterior surface is covered by the conjunctiva. The two extremities of the tarsus are continuous with the external and internal palpebral ligaments. To the convex border of the tarsus is attached a fascia which runs from it to the margin of the orbit, and upon either side is connected with the palpebral ligaments (fascia tarso-orbitalis). Hence, when the lids are shut the orbit is closed in all over anteriorly by fibrous structures which together form the orbital septum —namely, the two tarsi in conjunction with the fascia tarso-orbitalis and the two palpebral ligaments (Fig. 3). The tarsus is called the cartilage of the lids. It is not, however, cartilage, but a very dense fibrillary connective tissue, in which are imbedded the Meibomian glands. These are elongated acinous glands which, lying parallel with each other, traverse the tarsus from its attached to its free border. They are longest in the middle of the tarsus, where the latter attains its greatest height, and grow progressively shorter toward the edges of the tarsus (Fig. 3). In their essential character the Meibomian glands are nothing but large sebaceous glands. Like the latter they secrete sebum, which lubri¬ cates the edges of the lids. By this the overflow of tears over the free border of the lids is hindered; the closure of the palpebral fissure is rendered water-tight; and, lastly, the skin of the border of the lid is protected from maceration by the tears. Acinous mucous glands are frequently found near the convex border of the tarsus (Fig. 1, w, and Fig. 3).
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