The Orbit and its Openings

The Orbit and its Openings

The orbit is a bony cavity that protects and houses the eyeball and its associated structures. It is shaped like a truncated cone, with its base facing forward and its apex facing backward.

Walls of the Orbit:

• Superior wall:

• Anteriorly: Orbital plate of the maxilla (in the anterior cranial fossa)

• Posteriorly: Lesser wing of the sphenoid bone

• Medial wall: The thinnest wall of the orbit, formed by:

• Orbital plate of the ethmoid bone

• Lacrimal bone

• A small portion of the body of the sphenoid bone

• Frontal bone

• Inferior wall:

• Composed of: Maxilla, a part of the zygomatic bone, and the palatine bone

• Forms the floor of the maxillary sinus

• Lateral wall:

• Formed by: Frontal process of the zygomatic bone and the greater wing of the sphenoid bone

Openings and Fissures:

• Lacrimal fossa: Located on the medial and superior walls.

• Lacrimal groove: Located on the medial wall.

• Optic canal: Located on the superior wall.

• Inferior orbital fissure: Separates the lateral wall from the inferior wall. It houses the infraorbital artery and nerve.

• Apex of the orbit:

• Located inside the superior orbital fissure.

• Located next to the optic canal of the lesser wing of the sphenoid bone.

• Optic canal:

• Bounded by the lesser wing and body of the sphenoid bone.

• Contains the optic nerve and ophthalmic artery.

• Superior orbital fissure:

• Bounded by the lesser wing of the sphenoid bone, the greater wing of the sphenoid bone, the body of the sphenoid bone, and the frontal bone.

• Contains the oculomotor nerve, trochlear nerve, abducens nerve, and the trigeminal nerve.

• Inferior orbital fissure:

• Bounded by the greater wing of the sphenoid bone, the maxilla, the palatine bone, and the zygomatic bone.

• Communicates with the pterygopalatine fossa and the sphenomaxillary fossa.

Note: This article provides basic information about the anatomy of the orbit. To understand the structures and functions in detail, you should refer to specialized medical literature.