The orbits are the two roughly pyramid shaped indentations in the middle of the front of the skull on either side of the nose that contain the eyes and their ancillary muscles and glands. Each is constructed of seven different bones.
Bulging eyes are usually caused when excess tissue, particularly fat, accumulates in an orbit, but can also be caused by a tumor. One of the key clinical signs of Graves' disease is bulging eyes due to the buildup of fibrous tissue and matrix proteins within the orbits. If the lacrimal gland swells, the eyes will be pushed away from it.