Lamina cribrosa of sclera

Where the optic nerve passes through the sclera, the latter forms a thin cribriform lamina, the lamina cribrosa scleræ; the minute orifices in this lamina serve for the transmission of the nervous filaments, and the fibrous septa dividing them from one another are continuous with the membranous processes which separate the bundles of nerve fibers.

One of these openings, larger than the rest, occupies the center of the lamina; it transmits the central artery and vein of the retina. Around the entrance of the optic nerve are numerous small apertures for the transmission of the ciliary vessels and nerves, and about midway between this entrance and the sclerocorneal junction are four or five large apertures for the transmission of veins (venæ vorticosæ).