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|Mar 29 2011, 8:07 PM EDT (current)||AndyC||272 words added|
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Key: Additions Deletions
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
2. Inferior 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.
3. Otic canal
- 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.
4. Infraorbital groove and infraorbital foramen
- 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.
5. Supraorbital notch or foramen
- Transmit the infraorbital nerve and vessels.
6. Anterior and posterior ethmoidal foramina
- Transmits the supraorbital nerve and vessels.
7. Nasolacrimal canal
- Transmit the anterior and posterior ethmoidal nerves and vessels, respectively.
- 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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