The orbit is the bony socket that contains and protects the eyeball and allows for the optic nerve to pass from the eye to the brain. The orbital region includes the surrounding bone and the muscles that control the eye, as well as nerves and blood vessels. Tumors may arise from any of these structures, but neurological surgeons primarily treat those of neural origin, which are the most common tumors of the orbit. Orbital tumors may arise from Schwann cells, cells in the sheaths that cover nerves. These usually benign tumors, called neurofibromas and schwannomas, can occur on any nerve in the area except the optic nerves, which lack Schwann cells. Another relatively common benign neurological tumor in this area is the optic glioma, a tumor that arises from glial cells, the supporting cells in the brain, which also are found in the optic nerve. Another tumor is the orbital meningioma, which comes from the meninges, the protective covering that surrounds the brain and optic nerves. These tumors may arise within the orbit, or may develop outside the orbit and grow to include it. Other tumors that occur in and around the orbit include osteomas and ossifying fibromas, which involve bone; hemangiomas and lymphangiomas, which come from the vascular system; rhabdomyosarcoma and fibrous histiocytoma, which arise from developmental cells; skin cancers on the eyelids; and metastatic tumors that spread to the area from other parts of the body.