Orbita – structure, function & diseases
Orbit
The orbit is the bony eye socket . Seven bones come together in this receptacle for the eye . The weakest point of the orbit is the floor, which is often affected by fractures after blows .
What is the orbit?
The orbits are the bony eye sockets. These are four to five centimeter deep pits in the skull in which the eyes and their appendages are located. 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. In addition to the bony eye socket, the lacrimal bone is also involved in the nasal bone .
The frontal bone is the front cranial roof and thus the upper wall of the cranial cavity. The upper jaw borders on the oral cavities as well as on the nasal and eye cavities. The cheekbones are a pair of facial bones and the ethmoid bone separates 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 is again a lower mid-cranial bone where it forms the posterior portion of the orbits. Inside the orbits are several holes through which the nerves and blood vessels of the eye and face pass. Around 4/5 of the orbits consist of fat , connective tissue and muscles, nerves and vessels. The eyeball makes up the last fifth .
Anatomy & Structure
The frontal and sphenoidal bones form the roof of each orbit. The maxilla, the zygomatic bone and the palatine bone each form the floor of the orbit. The lateral wall is formed by the zygomatic bone and the sphenoid bone, while the maxilla, the lacrimal bone, the ethmoid bone and the frontal orbital surface together with the minor sphenoidal wing form the middle wall of the orbits. The structure of meeting bones has the shape of a four-sided pyramid in each orbit. The base of this pyramid faces forward. The tip points into the depths of the skull .
The contents of the orbits are separated from the bones by the periorbital tissue layer. Frontally, the bony orbits have an entrance called 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. This is where pathways enter the eye sockets. Many nerves and vessels also pass through the infraorbital sulcus, which forms an entrance to the infraorbital canal. Nerves and blood vessels return to the cranial cavity through the anterior ethmoidal foramen and the posterior ethmoidal foramen.
Function & Tasks
The orbits are the receptacles for the eyes and their supply of blood vessels and nerves. They also serve the bony protection of the eye. Since the eye socket is around five centimeters deep, the eyeball, including its supply structures, is not damaged as easily as if it were lying flat on the face. The seven adjoining 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 also have protective tasks. The holes in the orbits offer nerves such as the optic nerve a passage. In this respect, the bony eye sockets also take on 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 the cranial nerves of the eye muscles 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 and the sixth cranial nerve nerve abducens. The eye socket also offers protection and additional stability to these structures. Some structures of the bony socket are stronger than others, providing better protection. The weaker structures include the lateral inner wall and the floor of the eye sockets. These weaker parts mainly play a role in connection with fractures.
Diseases
Discomfort with the orbits is most often 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 manifestations is the orbital floor fracture, in which the orbital cavity breaks through to the maxillary sinus. A fracture of the orbital floor usually manifests itself in double vision, which can be traced back to a restricted movement of the eye.
Muscle tissue is often pinched in the hernia line. Connective and retaining tissue slips in just as often, and more rarely nerve tissue. As soon as nerve tissue is affected, sensory disturbances in the face can be added to the double vision. Orbital floor fractures can be treated surgically. Especially when muscles or nerves are trapped, such reconstructive treatments of the orbit take place, since the trapped structures could otherwise die. In particular, the freeing of nerves from a fracture can cause permanent damage to the jammed nerve.
As part of the reconstructive surgery, the patient is usually fitted with a tiny metal plate that holds the floor of the eye socket together and thus helps it grow together. The plate can, but does not necessarily have to be removed. In the worst case, if the orbital floor fracture is left untreated, the eye can sag a bit. Sometimes the orbits are also affected by inflammation or cysts . However, fractures remain the most common occurrence.
Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.