Eye socket


The eye socket (Orbita) is a pyramid-shaped cave in the facial skull, which receives the eyeball and its numerous appendages (muscles, nerves, vessels, lacrimal apparatus). The wall of the eye socket consists of seven skull bones, is lined with periosteum and in places very thin. Read everything important about the eye socket: structure, function, diseases and injuries!

What is the eye socket?

The bony eye socket has the shape of a four-sided pyramid, the base of which faces forwards and whose tip is directed towards the center. This base forms the orbital entrance (Aditus orbitae), which is almost rectangular with walls that are almost vertical in the middle and on the outer edge. The upper and lower edges lower slightly from the center of the face to the outside. The axis of the orbita funnel is directed slightly outwards and upwards. The entire eye socket is about four to five inches deep.

The bony boundary of the eye socket

The bony borders of the orbit are formed by seven skull bones:

The frontal bone (os frontale) and the horizontal wings of the sphenoid bone (os sphenoidale) form the so-called roof of the orbit. This roof acts as a border to the frontal sinus in the anterior region, as a border to the anterior cranial fossa and the frontal lobe of the brain in the posterior region. There is a deep pit for the lacrimal sac in the front and sides of the orbita roof.

The medial border of the orbit consists of the frontal lacrimal bone and the ethmoid bone in the middle and posterior. In the wall of the teardrop a pit for the lacrimal sac is inserted, which continues down into the tear-nasal canal, which opens below the lower nasal turbinate.

The lower wall of the orbit is formed by the upper jaw (maxilla), cheekbone (os zygomaticum) and a small appendage of the palatine bone (os palatinum).

The lateral wall of the orbit runs obliquely from the front outside to the back inside and is thus longer than the middle wall. It is formed by the zygomatic bone (Os zygomaticum) and the larger sphenoid wing.

The seven skull bones, which form the wall of the eye socket, are lined with periosteum and in places very thin: down to the maxillary sinus the bone is only 0.5 millimeters thick; Towards the back center, only 0.3 millimeters of thin bone or even the periosteum separates the orbit from the sieve cells.

What is the function of the eye socket?

The orbit takes up the eyeball (bulbus) and its numerous appendages: muscles, nerves, vessels, lacrimal apparatus. It provides bony protection for these structures. The majority of the eye socket is filled with adipose tissue with connective tissue, which serves as a cushion for the eyeball.

Where is the eye socket located?

The paired eye socket is located in the upper part of the facial skull. At the back of the orbit are the sphenoid sinus with the hypophysis and the middle fossa with the chiasm (optic nerve junction in the center of the middle fossa).

Above the eye socket are the anterior fossa and frontal sinus.

The bony channel for the optic nerve (optic nerve) and the ophthalmic artery (ophthalmic artery) is located at the tip of the orbit, next to the ophthalmic vein (vena ophtalmica), which opens into the cavernous sinus (a venous network). Also at this point, several cranial nerves pass through the bone.

What problems can the eye socket cause?

Particularly prone to infections is the wall of the orbit to the nose, which may have gaps, especially in the elderly. Through these gaps, inflammation of the ethmoidal cells can spread to the eye socket. Sinus infections can also spread to the orbit.

The frontal sinus can extend far into the orbital roof, causing sinusitis to spread into the eye socket or cranial cavity.

The orbita floor is closely related to the maxillary sinus. As a result, a dental root inflammation can spread to the eye socket.

At the apex of the orbital pyramid, inflammation through the bone openings may spread to the cranial cavity and cavernous sinus. In the latter case, the inflammation can cause a life-threatening vascular blockage by a blood clot (cavernous sinus thrombosis).

Fractures of the midface often affect the orbit. A blow directly to the eye that breaks the orbita floor is called a blow-out fracture.

Bone tumors (osteosarcoma) of the eye socket displace the eye outwards.

In an exophthalmos, the eyeball emerges from the eye socket out. Possible causes include inflammation in the area of ​​the orbit, as in Graves' disease.