The superior orbital fissure is a narrow opening located within the bony orbit of the eye, which serves as a passageway for several important nerves and blood vessels.
Structure
The superior orbital fissure is a thin, triangular-shaped opening located between the sphenoid and ethmoid bones at the base of the skull. It is located above the orbital rim and below the lesser wing of the sphenoid bone. The superior orbital fissure is bordered by the orbital process of the frontal bone medially, the greater wing of the sphenoid bone laterally, and the orbital plate of the ethmoid bone inferiorly.
It is divided into two parts: the medial and lateral parts. The medial part is wider and more triangular in shape, while the lateral part is narrower and more elongated. The superior orbital fissure also contains a number of bony ridges and grooves that help to guide and protect the structures passing through it.
Location
The superior orbital fissure is located within the bony orbit of the eye, which is a hollow cavity within the skull that houses the eye and its associated muscles and connective tissues. The bony orbit is formed by several bones of the skull, including the frontal bone, sphenoid bone, ethmoid bone, zygomatic bone, and lacrimal bone.
The superior orbital fissure is located at the base of the bony orbit, where it connects the orbital cavity to the cranial cavity. It is situated above the orbital rim and below the lesser wing of the sphenoid bone.
Function
The superior orbital fissure serves as a passageway for several important nerves and blood vessels that supply the eye and surrounding structures. These include:
Nerves
The oculomotor nerve (CN III) is responsible for innervating several of the muscles that control eye movement, including the superior, inferior, and medial rectus muscles, as well as the inferior oblique muscle. It also carries parasympathetic fibers to the sphincter pupillae muscle and the ciliary muscle, which control the size of the pupil and the focusing ability of the eye, respectively. The oculomotor nerve passes through the medial part of the superior orbital fissure.
The trochlear nerve (CN IV) is responsible for innervating the superior oblique muscle, which controls eye movement and helps to maintain proper alignment of the eyes. It passes through the lateral part of the superior orbital fissure.
The abducens nerve (CN VI) is responsible for innervating the lateral rectus muscle, which moves the eye outward and away from the midline of the body. It also passes through the lateral part of the superior orbital fissure.
Blood vessels
The ophthalmic artery is the main blood supply to the eye and surrounding structures. It passes through the medial part of the superior orbital fissure and branches into several smaller arteries, including the central artery of the retina, which supplies blood to the retina.
The superior ophthalmic vein is a large vein that drains blood from the eye and surrounding structures. It passes through the lateral part of the superior orbital fissure and empties into the cavernous sinus, which is a large venous structure located within the cranial cavity.
Clinical Significance
The superior orbital fissure and the structures passing through it are important for maintaining proper eye function and coordination. Any damage to these structures can result in vision problems and other ocular symptoms.
Trauma
Trauma to the eye or surrounding structures can cause damage to the nerves and blood vessels passing through the superior orbital fissure. This can lead to vision problems, including double vision, and difficulty moving the eye in certain directions. In severe cases, trauma to the superior orbital fissure can also cause damage to the optic nerve, which can result in permanent vision loss.
Tumors
Tumors can grow within the bony orbit and compress the structures passing through the superior orbital fissure. This can lead to vision problems and difficulty moving the eye. Tumors that involve the superior orbital fissure may require surgical intervention to remove them and relieve pressure on the affected structures.
Infection
Infection in the eye or surrounding structures can cause inflammation and swelling, which can compress the structures passing through the superior orbital fissure. This can lead to vision problems and difficulty moving the eye. Treatment may involve the use of antibiotics and other medications to clear the infection and reduce inflammation.
Anomalies
In some cases, the superior orbital fissure may be unusually large or small, or may have an abnormal shape or location. This can cause problems with the structures passing through it and lead to vision problems and other ocular symptoms. In some cases, surgical intervention may be necessary to correct the anomaly and restore proper function.
