The organs of vision : their structure and functions / by G.J. Witkowski ; tr. by Henry Power.

  • Gustave-Joseph Witkowski
Date:
[1878?]
Catalogue details

Licence: Public Domain Mark

Credit: The organs of vision : their structure and functions / by G.J. Witkowski ; tr. by Henry Power. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    17/44 (page 17)
    ii. —Orbicularis Palpebrarum Muscle. —This muscle is composed of two sets of fibres, the excentric, or orbital (4), and the concentric (5), or ciliary, which are paler, and situated in the lid itself. These fibres are attached to a fibrous cord named the tendon of the orbicularis (24), situated at the in- ternal angle of the eye, and directed outwards to be inserted into the deep surface of the skin. The tendon of the orbicularis is bifurcated, the anterior branch, or dh'ed portion, being that which is seen through the transparent skin, especially in a black eye ; and it may also be made prominent by drawing the external commissure outwards. Its posterior or reflected branch (44) is attached to the crest of the os unguis^ behind tliQlacrymal sac(37). There is yet another muscle, described as an appendage of the orbicularis muscle, and to which the name of Horner’s muscle has been applied. This little muscle springs also from the os unguis^ and terminates in two elongated processes, or tongues, in the sub- stance of the lids, and near their ciliary border. The use of the orbicular muscle is to close the lids. It plays an important part in effecting the act of vnnhing, and in slee]j. It is the antagonist of the levator pal^ehrce superioris muscle, or ele- vator of the upper lid (66), the name of which indicates its action, and its paralysis is characterised by an inability to close the lids, from which circumstance the name of lagophthalmus (Xayw^, hare, eye) has been applied to this affection. In contracting the orbicularis, it drags upon the skin of the temple and throws it into folds that have received the name of crow's feet. With age the skin becomes flaccid, and the folds are permanent. iii. Tarsal Fibro-Cartilages.—These thin, long, and narrow laminee (18, 21) occupy the free border of the lids, and form, so to speak, the skeleton of the palpebrse, the form of which they serve to maintain. They may be compared, as Cruveilhier has pointed out, to the pieces of wood that are placed beneath tables to prevent them from doubling up. They are kept in posi- tion by the broad suspensory ligaments (17, 19) of the lids which are attached to the borders of the orbit. Imbedded in the posterior surfaces of the cartilages of both lids are small sinuous elongated canals, constricted here and there, which are named the Meibomian glands (35). These glands are more nume- rous in the upper lid, where from thirty to forty may be counted and are destined to secrete an oily matter which coats the edge of the lids and prevents the tears from flowing over the cheeks. The orifices of these glands are sometimes obstructed, and the pro- ducts of their secretion accumulate in the excretory ducts, which 3