Bony Orbit |

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Mar 29 2011, 8:07 PM EDT (current) AndyC 272 words added
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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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