Round opening, round canal opening - a small hole in the walls of the canals, which serves for the exit or entry of secreted glands and blood vessels passing into them.
In humans, the round openings are located on the lateral walls of the upper jaw, on the palatine roof, in the medial wall of the optic canal of the brain, and also in the largest opening of the pyramid of the temporal bone. Several round holes extending from the initial part of the optic canal to the optic nerve and located between the frontal and sphenoid processes of the pyramids in the lower part of the sella turcica form a round depression (sinus rotundus), located above the optic chiasm. In the pyramids of the temporal bones there are round openings through which the oblique and horizontal spines exit into the area of the cerebellopontine angle.