Bones of the orbit - Human Anatomy | Kenhub

Summary

This tutorial delves into the intricate anatomy of the bony orbit, the skeletal structure surrounding the eye. It covers the seven bones that form the orbit, including the frontal, maxilla, zygomatic, sphenoid, ethmoid, lacrimal, and palatine bones, explaining their specific contributions to the orbital walls. The tutorial also discusses key landmarks, foramina, and fissures within the orbit, which allow the passage of nerves and blood vessels. It concludes with a clinical focus on orbital blowout fractures, a common injury, and emphasizes the importance of understanding orbital anatomy in medical practice.

Takeaways

• 😀 The orbit of the eye is formed by seven bones, creating a cavity that houses the eyeball and its related structures like muscles, nerves, and blood vessels.
• 😀 The frontal bone contributes to the superior wall of the orbit, specifically the orbital surface, and contains important landmarks like the supraorbital foramen.
• 😀 The maxilla is a bilateral bone that makes up the infraomedial part of the orbit and includes landmarks such as the frontal process and infraorbital foramen.
• 😀 The zygomatic bone, or cheekbone, forms the infra-lateral part of the orbit and has features like the orbital tubercle and its contribution to the orbital margin.
• 😀 The sphenoid bone, located at the posterior wall of the orbit, includes the greater and lesser wings, with important structures like the optic canal and superior orbital fissure.
• 😀 The ethmoid bone contributes to the medial wall of the orbit, with the orbital plate and foramina allowing passage for neurovascular structures.
• 😀 The palatine bone, though small, helps form part of the posterior orbital wall with its orbital process.
• 😀 The lacrimal bone contributes to the medial wall of the orbit and features the posterior lacrimal crest, which forms the boundary of the lacrimal fossa.
• 😀 Clinical relevance includes orbital blowout fractures, often occurring due to trauma, typically affecting the inferior or medial walls of the orbit.
• 😀 In the case of orbital fractures, CT scans are the best diagnostic tool, as they provide detailed information on bone injury and potential complications like intraorbital hemorrhage or muscle damage.

Q & A

What bones make up the bony orbit?

The bony orbit is made up of seven bones: the frontal bone, maxilla, zygomatic bone, sphenoid bone, ethmoid bone, palatine bone, and lacrimal bone.

What is the function of the bony orbit?

The primary function of the bony orbit is to provide a stable and enclosed environment for the eyeball and its associated muscles, nerves, and blood vessels.

Which part of the frontal bone contributes to the orbit?

The orbital part of the frontal bone, specifically its orbital surface, contributes to the roof of the orbital cavity.

What is the supraorbital foramen, and what does it transmit?

The supraorbital foramen is a small hole in the supraorbital margin of the frontal bone. It transmits the supraorbital vessels and nerve, which supply the forehead.

How does the maxilla contribute to the orbital cavity?

The maxilla contributes to the inferior and medial parts of the orbital margin, and also forms a portion of the orbital floor. It contains the infraorbital foramen, which transmits the infraorbital nerve and blood vessels.

What is the orbital surface of the zygomatic bone?

The orbital surface of the zygomatic bone forms part of the floor and lateral walls of the orbit. It helps complete the orbital margin between the frontal and maxillary bones.

What is the role of the sphenoid bone in the bony orbit?

The sphenoid bone contributes to the posterior wall of the orbit, particularly through its greater and lesser wings. It also contains important openings like the optic canal and superior orbital fissure.

What structures pass through the superior orbital fissure?

The superior orbital fissure allows passage of the oculomotor nerve, trochlear nerve, ophthalmic nerve branches, abducens nerve, and superior and inferior ophthalmic veins.

What is the clinical relevance of orbital blowout fractures?

Orbital blowout fractures are commonly caused by trauma to the facial skeleton, often leading to prolapse of orbital fat and muscles. These fractures can be diagnosed with CT scans and may require surgery depending on severity.

What is the lacrimal bone's role in the orbit?

The lacrimal bone contributes to the medial wall of the orbit and features a posterior lacrimal crest, which forms part of the lacrimal fossa.