Practical anatomy: a manual of dissections / by Christopher Heath.

  • Christopher Heath
Date:
1870
Catalogue details

Licence: Public Domain Mark

Credit: Practical anatomy: a manual of dissections / by Christopher Heath. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    246, in Cj^, from the ciliary ligament to the ciliary processes ; and the other (m cj, a circular band of fibres. The use of the latter is not well settled. The fibres which run to the ciliary processes, pull these forward. These, being con- nected with the h^'aloid membrane and the suspensory liga- ment of the lens at the zone of Zinn, pull them forward and thus relax the tension on the anterior surface of the lens, and allow it to become more convex. By increasing its cur- vature, its refraction of light is increased, and accommoda- tion for nearer objects is effected.] [In order to understand the ciliary processes it is best to observe them first from behind. To do this, take the second eye which was divided into antero-posterior halves (p. 536). In the anterior half, the lens will be seen surrounded by a black radiating ring, the ciliary pro- cesses (Fig. 247, 4). The vitreous humor and the lens together can then be carefully detached by the handle of the knife assisted by their own weight and by gentle shaking. The ciliary processes will remain with the sclerotic, &c., and surrounding the lens will be seen a zone or ring of radii like the spokes of a wheel, the zone of Zinn. The bases of the ciliary processes (the ends next the pupil) can be raised on the knife handle, and the apices will be observed to end at the anterior border of the retina, which by its waving outline is called the ora serrata. The pigment can be brushed away by a camel's hair pencil and water, when their relation to the iris will be better understood (and also the radiating fibres of the iris will be adniirably well seen). To see their relation to the lens, and its suspensory ligament return to the third eye, lift up the free (pupillary) border of the iris, and, holding its posterior surface towards your own eye, remove it by the scissoi'S, being careful not to injure the anterior edge of the ciliary processes just underneath its attached border. These can now be lifted as before disclosing underneath them the suspensory ligament of the lens and through it the edge of the lens itself. The canal of Petit (Fig. 246, c p) can now either be inflated by a fine blowpipe, or a bristle can be inserted into it.] The Ciliary Processes (Figs. 246, p c, and 247, 4) are vascular fringes which resemble a series of plaits in appear- ance, and which form a circular curtain, parallel but pos- terior to the iris, from which they are separated by the posterior chamber. They fit into a corresponding series of plaitings in the hyaloid membrane of the vitreous humor [and the suspensory ligament of the lens. This zone or belt of plaitings, blackened hy the pigment of the ciliary processes which fitted into them, is the Zone of Zinn (Fig. 243, 10, p. 534) and is well seen around the lens and on the anterior part of the vitreous humor which was turned out of the second eye dissected].