The orbital cavity, also known as the orbit, is a bony socket located within the skull that houses and protects the eye and its associated structures. It is an important and complex structure in the human body, playing a vital role in vision and eye movement.
Structure
The orbital cavity is a four-walled, pyramid-shaped structure that is formed by several bones of the skull, including the frontal bone, zygomatic bone, sphenoid bone, and ethmoid bone. The orbital cavity is bounded by the orbital margin, a bony ridge that encircles the orbit and separates it from the surrounding facial structures.
It is divided into two parts: the anterior and posterior orbital cavities.
- The anterior orbital cavity is the larger of the two and contains the eyeball, extrinsic eye muscles, and the lacrimal gland.
- The posterior orbital cavity is smaller and contains the optic nerve, oculomotor nerve, and the levator palpebrae superioris muscle.
The orbital cavity is lined with a thin, vascular membrane called the orbital periosteum, which helps to nourish the structures within the orbit and protect them from mechanical trauma. The orbital periosteum is richly supplied with blood vessels and nerve endings, making it highly sensitive to touch and pressure.
Location
The orbital cavities are located within the skull, one on each side of the head. They are situated in the frontal bone, just above the nasal cavity and below the frontal lobe of the brain. The orbital cavities are separated by a thin partition of bone called the septum orbitale.
They are located in a strategic position within the skull, providing protection and support for the eye and its associated structures. The bones of the orbital cavity are thick and strong, helping to shield the eye from mechanical trauma and injury.
Function
The main function of the orbital cavity is to house and protect the eye and its associated structures. The orbital cavity provides a stable and supportive environment for the eye, allowing it to move and function properly.
The orbital cavity also plays a vital role in vision. The eye is able to move within the orbital cavity, allowing it to focus on objects at different distances. The extrinsic eye muscles, which are located within the orbital cavity, are responsible for controlling the movement of the eye. These muscles are innervated by cranial nerves III, IV, and VI, which are responsible for controlling eye movement.
The orbital cavity is also home to the lacrimal gland, which is responsible for producing tears. Tears are necessary for maintaining the health of the eye, as they help to moisturize and protect the surface of the eye from debris and foreign particles.
Clinical Significance
The orbital cavity is susceptible to a variety of disorders and conditions that can affect the eye and its associated structures. Some of the more common disorders that can affect the orbital cavity include orbital cellulitis, orbital fractures, and orbital tumors.
Orbital cellulitis
Orbital cellulitis is a serious infection that affects the tissues of the orbital cavity. It is typically caused by bacteria that enter the orbit through the sinuses or the eye. Symptoms of orbital cellulitis include redness and swelling of the eye, fever, and eye pain. Treatment usually involves antibiotics and, in severe cases, hospitalization.
Orbital fractures
Orbital fractures are breaks or cracks in the bones of the orbital cavity. They can be caused by trauma, such as a blow to the head or an automobile accident. Symptoms of an orbital fracture may include double vision, eye pain, and swelling around the eye. Treatment may involve the use of medications to control inflammation and swelling, and surgery may be necessary to repair the fracture.
Orbital tumors
Orbital tumors are abnormal growths that occur within the orbital cavity. These tumors can be benign (non-cancerous) or malignant (cancerous). Symptoms of orbital tumors may include vision problems, double vision, swelling around the eye, and eye pain. Treatment may involve surgery to remove the tumor, radiation therapy, or chemotherapy, depending on the type and stage of the tumor.
In addition to these conditions, the orbital cavity can also be affected by other disorders such as orbital cysts, thyroid eye disease, and orbital pseudotumor. These conditions can lead to a variety of symptoms, including vision problems, double vision, and eye pain, and may require medical or surgical treatment.
