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

  • Heath, Christopher, 1835-1905.
Date:
1885
Catalogue details

Licence: Public Domain Mark

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

    627/682 (page 535)
    is a non-vascular structure, no blood-vessels existing in it and its nourishment being derived from the surrounding structures. Minute branches of the ciliary nerves have however been traced into and through it. [Holding the eye lightly with the left hand, the scalpel is to be thiust through the margin of the cornea into the anterior chamber, when the aqueous humour will necessarily escape. With scissors the cornea may then be removed entirely.] The Anterior Chamber (Fig. 2V0, 3) is the space between the cornea and the iris. It communicates with the posterior chamber through the pupil, and is filled with the aqueous humour. The Iris (Fig. 270,2) is the highly vascular curtain which separates the anterior from the posterior chamber. It is composed of involun- tary muscular fibres, blood-vessels, and pigment, and may be con- sidered to be a prolongation of the choroid coat. In man, the pigment of the iris is of various colours, but it is absent altogether in albinos, and occasionally the iris itself is wanting. The Pupil is a circular opening (in man) in the centre of the iris, which varies in size according to the contraction of the circular fibres of the iris under the influence of light. The Posterior Chamber is smaller than the anterior, and can be hardly said to exist when the aqueous humour has been let out. It is between the iris and the anterior layer of the capsule of the lens. [In order to see the choroid coat entire, a fresh eye should be taken, and a puncture having been made through the sclerotic, about its middle, a blowpipe is to be introduced, through which air may be forced between the sclerotic and choroid coats, and they will thus be separated from one another. The sclerotic may then be cautiously divided circularly, and the posterior cup-like portion of the sclerotic being left as a support to the eye, the anterior part (with the cornea) is to be carefully detached from the choroid. In order to do this it will be necessary to scrape the interior of the sclerotic with the handle of the scalpel, so as to tear through the ciliary muscle which attaches the choroid to the sclerotic coat.] The Choroid Coat (Fig. 271, 3) is a vascular structure containing pigment, expanded over the whole of the posterior portion of the globe of the eye, and continuous in front with the iris. It is pierced by the optic nerve, at which point it is closely connected to the sclerotic ; but is attached to the inner surface of that coat only by a delicate fibrous tissue, called the memhrana fusca. On the outer