ABSTRACT
The orbit functions to protect, support, and maximize function of the eye. The bony orbit separates the orbital contents from the intracranial fossa and the paranasal sinuses. The superior wall is separated from the frontal lobe of the brain by a thin bony plate, which can be easily penetrated by a sharp object passing into the orbit. Anteriorly the frontal sinus may be the source of an inflammatory process extending into the orbit. The lacrimal fossa is located in the anterolateral bony orbit, and erosion of the bone indicates a potentially malignant extension of a tumor of the lacrimal gland. The inferior orbital wall is easily penetrated by neoplasms arising in the maxillary sinus. Similarly, the medial wall, formed by the thin ethmoid bones, may be affected when a tumor arises in the nasal cavity or the paranasal sinuses. The lower aspect of the medial wall contains the lacrimal fossa which surrounds the lacrimal sac and may be eroded by extension of inflammatory or neoplastic processes. There are several apertures in the orbital bone that allow the passage of blood vessels and nerves. These include the narrow optic foramen or canal, situated at the apex of the orbit, through which pass the optic nerve, the ophthalmic artery and sympathetic nerve fibers. The superior orbital
fissure transmits the sensory nerve (V) and the motor nerves (III, IV and VI) to the extraocular muscles, which enter the orbit in close relation with the superior ophthalmic vein. It is in this region that a space-occupying lesion can cause most damage to the blood vessels and nerves. The infraorbital sulcus crosses the floor of the orbit and carries the infraorbital artery, infraorbital vein, and infraorbital nerve from the infraorbital fissure to the infraorbital foramen. Clinically, the infraorbital foramen provides a route of spread for infection or maxillary tumors to the orbit and the skull base.
