Bony Orbit

Bony Orbit

A. Orbital margin

• Is formed by the frontal, maxillary, and zygomatic bones.

B. Walls of the orbit

• Superior wall or roof : orbital part of frontal bone and lesser wing of sphenoid bone.
• Lateral wall : zygomatic bone (frontal process) and greater wing of sphenoid bone.
• Inferior wall or floor : maxilla (orbital surface), zygomatic, and palatine bones.
• Medial wall : ethmoid (orbital plate), frontal, lacrimal, and sphenoid (body) bones.

C. Fissures, canals, and foramina

1. Superior orbital fissure

• Communicates with the middle cranial fossa and is bounded by the greater and lesser wings of the sphenoid.
• Transmits the oculomotor, trochlear, abducens, and ophthalmic nerves (three branches) and the ophthalmic veins.

2. Inferior orbital fissure

• Communicates with the infratemporal and pterygopalatine fossae.
• Is bounded by the greater wing of the sphenoid (above) and the maxillary and palatine bones (below).
• Transmits the maxillary (or infraorbital) nerve and its zygomatic branch and the infraorbital vessels.
• Is bridged by the orbitalis (smooth) muscle.

3. Otic canal

• Connects the orbit with the middle cranial fossa.
• Is formed by the two roots of the lesser wing of the sphenoid and is situated in the posterior part of the roof of the orbit.
• Transmits the optic nerve and ophthalmic artery.

4. Infraorbital groove and infraorbital foramen

• Transmit the infraorbital nerve and vessels.

5. Supraorbital notch or foramen

• Transmits the supraorbital nerve and vessels.

6. Anterior and posterior ethmoidal foramina

• Transmit the anterior and posterior ethmoidal nerves and vessels, respectively.

7. Nasolacrimal canal

• Is formed by the maxilla, lacrimal bone, and inferior nasal concha.
• Transmits the nasolacrimal duct from the lacrimal sac to the inferior nasal meatus.

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