Henry Gray (18251861). Anatomy of the Human Body. 1918.
the sulcus circularis corneæ it is bounded externally by the trabecular tissue already described as forming the inner wall of the sinus venosus scleræ. Between this tissue and the anterior surface of the attached margin of the iris is an angular recess, named the iridial angle or filtration angle of the eye (Fig. 870). Immediately outside the filtration angle is a projecting rim of scleral tissue which appears in a meridional section as a small triangular area, termed the scleral spur. Its base is continuous with the inner surface of the sclera immediately to the outer side of the filtration angle and its apex is directed forward and inward. To the anterior sloping margin of this spur are attached the bundles of trabecular tissue just referred to; from its posterior margin the meridional fibers of the Ciliaris muscle arise.
FIG. 870 Enlarged general view of the iridial angle. (Arthur Thomson.) (See enlarged image)
Structure (Fig. 871).The cornea consists from before backward of four layers, viz.: (1) the corneal epithelium, continuous with that of the conjunctiva; (2) the substantia propria (3) the posterior elastic lamina; and (4) the endothelium of the anterior chamber.
The corneal epithelium (epithelium corneæ anterior layer) covers the front of the cornea and consists of several layers of cells. The cells of the deepest layer are columnar; then follow two or three layers of polyhedral cells, the majority of which are prickle cells similar to those found in the stratum mucosum of the cuticle. Lastly, there are three or four layers of squamous cells, with flattened nuclei.
The substantia propria is fibrous, tough, unyielding, and perfectly transparent. It is composed of about sixty flattened lamellæ, superimposed one on another. These lamellæ are made up of bundles of modified connective tissue, the fibers of which are directly continuous with those of the sclera. The fibers of each lamella are for the most part parallel with one another, but at right angles to those of adjacent lamellæ. Fibers, however, frequently pass from one lamella to the next.