. The anatomy of the human body. Human anatomy; Anatomy. THE MUSCLES OF THE EYE. 649 the eyelids, in that part of those margins which extends between the lachrymal tuber- cles and the internal commissure ; but it is upon a plane posterior to these margins, so that it does not prevent their mutual contact. It is covered by a fold of the conjunctiva, which gives it a reddish aspect; it presents a great number of openings, through which a waxy secretion exudes, and projecting from it are several small hairs, which may be- come so long as to produce ophthalmia. The caruncula lachrymalis is compose
. The anatomy of the human body. Human anatomy; Anatomy. THE MUSCLES OF THE EYE. 649 the eyelids, in that part of those margins which extends between the lachrymal tuber- cles and the internal commissure ; but it is upon a plane posterior to these margins, so that it does not prevent their mutual contact. It is covered by a fold of the conjunctiva, which gives it a reddish aspect; it presents a great number of openings, through which a waxy secretion exudes, and projecting from it are several small hairs, which may be- come so long as to produce ophthalmia. The caruncula lachrymalis is composed of se- baceous follicular glands, of the same nature as the Meibomian glands. It was for a long time considered to be a second lachrymal gland. In order to obtain a good view of the orifices, and of the light-coloured and sometimes very numerous hairs of the carun- cula lachrymalis, that body should be covered with ink or a solution of carmine, and then examined with a lens. Vessels and Nerves of the Eyelids.—The arteries are the internal and external palpe- bral branches of the ophthalmic, and the palpebral branches of the temporal, infra-orbital, and facial arteries. I have already said that the palpebral arteries form two arches, one for each eyelid. The veins have the same name, follow the same direction, and open into the corre- sponding venous trunks. The nerves are derived from two sources, viz., the facial and the fifth nerve. Uses.—The eyelids protect the eye from the action of light and air, and of any parti- cles floating in the latter; by a sweeping movement, they clean the surface of the or- gan, over which they also spread the lachrymal fluid, which serves as a protection to the eyeball against the action of the air. The eyelids, from their capability of being inter- posed between the eye and external objects, place the exercise of vision under the con- trol of the will. The Muscles of the Eye, and the Levator PalpebrcR Superioris. The muscles of the eye are
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