The orbit is the bony socket of the eye. Seven bones come together in this receptive shell for the eye. The weakest part of the orbit is the floor, which is often affected by fractures after blows.
What is the orbit?
The orbits are the bony orbits of the eyes. These are four- to five-centimeter-deep pits in the skull that contain the eyes and their appendages. These pits are each composed of seven bones. In addition to the frontal bone, the lacrimal bone and the upper jaw, the zygomatic bone, the ethmoid bone and the palatine bone meet here. The lacrimal bone is also involved in the nasal bone in addition to the bony orbit. The frontal bone is the anterior roof of the skull and thus the upper wall of the cranial cavity. The maxilla is adjacent to the oral cavities as well as the nasal and orbital cavities. The zygomatic bone is a paired facial bone and the ethmoid bone demarcates the cranial cavity from the face at the end of the nasal cavity. The palatine bone is primarily involved in the nasal and oral cavities. The sphenoid bone is again a cranial bone in the lower middle region, where it forms the posterior part of the orbits. Inside the orbits are several holes through which pass nerves as well as blood vessels of the eye and face. About 4/5 of the orbits consist of fat, connective tissue, muscles, nerves and vessels. The eyeball makes up the last fifth.
Anatomy and structure
The os frontale and the os sphenoidale form the roof of each eye socket. The maxilla, os zygomaticum, and os palatinum each form the orbital floor. The lateral wall is formed by the Os zygomaticum and the Os sphenoidale, while the maxilla, the Os lacrimale, the Os ethmoidale and the Facies orbitalis ossis frontalis together with the Ala minor ossis sphenoidalis form the medial wall of the orbits. The structure of meeting bones has the shape of a quadrilateral pyramid in each orbit. The base of this pyramid points anteriorly. The tip points into the depths of the skull. The contents of the orbits are separated from the bones by the periorbita tissue layer. Frontally, the bony orbits have an entrance called the aditus orbitalis, which is bordered by the bony orbital rim. There is a connection between the orbits and the middle cranial fossa with the superior orbital fissure and the optic canal. Here, conduit pathways enter the orbits. Many nerves and vessels also pass through the infraorbital sulcus, which forms an entrance to the infraorbital canal. Nerves and blood vessels re-enter the cranial cavity through the ethmoidal anterior foramen as well as the ethmoidal posterior foramen.
Function and Tasks
The orbitals are the receptive sheaths for the eyes and their supplying conduits of blood vessels and nerves. They also serve to provide bony protection for the eye. Since the orbit is about five centimeters deep, the eyeball, including its supply structures, is thus not as easily damaged as if it were lying flat on its face. The seven adjacent bones of the orbits enclose and even completely protect the eyeball on three sides. In addition to the bones, the periorbitae, the fat and the connective tissue of the eye sockets play a special protective role. Meanwhile, the holes in the orbits provide a passage for nerves such as the optic nerve. In this respect, the bony orbits also assume the tasks of a supply-structural guide rail. In addition to the optic nerve, the ophthalmic artery, the inferior ophthalmic vein, the lacrimal ducts, the zygomatic nerve and the infraorbital nerve are guided from here. The orbital fissure also carries cranial nerves of the ocular musculature and the sensory bulb. These cranial nerves include the third cranial nerve oculomotor nerve, the fourth cranial nerve trochlear nerve, and the first fifth cranial nerve ophthalmic nerve, as well as the sixth cranial nerve abducens. Thus, the orbit also provides protection and additional stability to these structures. Some structures of the bony orbit are stronger than others, providing better protection. The weaker structures include the lateral inner wall and the floor of the orbits. These weaker parts play a role especially in connection with fractures.
Diseases
Complaints involving the orbits are usually the result of a blow to the eye. Often, in the context of such scenarios, the weak parts of the orbits are affected by fractures. One of the most common occurrences is orbital floor fracture, in which the orbit breaks through to the maxillary sinus.Most often, an orbital floor hernia manifests as double vision due to restricted eye movement. Muscle tissue is often trapped in the hernial cleft. Connective and retaining tissue, and less frequently nerve tissue, slips in just as frequently. Once nerve tissue is involved, sensory disturbances in the face may be added to the double vision. Ruptures of the orbital floor can be treated surgically. Especially when muscles or nerves are trapped, such reconstructive treatments of the orbit take place, as the trapped structures may otherwise die. Specifically, freeing nerves from a hernial fissure can still permanently damage the pinched nerve. During reconstructive surgery, the patient is usually given a tiny metal plate to hold the floor of the orbit together to help it grow back together. The plate may or may not be removed. If the orbital floor is left untreated, the eye can sag a bit in the worst case. Sometimes the orbits are also affected by inflammation or cysts. Fractures, however, remain the most common occurrence.
