Anatomy

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Slide 23

The thin orbital floor is easily damaged by direct trauma to the globe, resulting in a "blowout" fracture with herniation of orbital contents into the maxillary antrum.

Slide 24

Infection within the sphenoid and ethoid sinuses can erode the paper-thin medial wall (lamina papyracea) and involve the contents of the orbit.

Slide 25

Defects in the roof (eg, neurofibromatosis) may result in visible pulsations of the globe transmitted from the brain.

Slide 26

Orbital Walls

Slide 27

The roof : frontal bone. Posteriorly, the lesser wing of the sphenoid bone containing the optic canal completes the roof.

The lacrimal gland is located in the lacrimal fossa in the anterior lateral aspect of the roof.

Slide 28

The lateral wall is separated from the roof by the superior orbital fissure, which divides the lesser from the greater wing of the sphenoid bone. The anterior portion of the lateral wall is formed by the orbital surface of the zygomatic (malar) bone. This is the strongest part of the bony orbit.

Slide 29

Suspensory ligaments, the lateral palpebral tendon, and check ligaments have connective tissue attachments to the lateral orbital tubercle.

Slide 30

The orbital floor is separated from the lateral wall by the inferior orbital fissure. The orbital plate of the maxilla forms the large central area of the floor and is the region where blowout fractures most frequently occur. The frontal process of the maxilla medially and the zygomatic bone laterally complete the inferior orbital rim. The orbital process of the palatine bone forms a small triangular area in the posterior floor.

Slide 31

medial wall :

ethoid bone ; lacrimal bone; The body of the sphenoid ( most posterior aspect of the medial wall). the angula r process of the frontal bone forms the upper part of the posterior lacrimal crest. The lower portion of the posterior lacrimal crest is made up of the lacrimal bone. The anterior lacrimal crest is easily palpated through the lid and is composed of the frontal process of the maxilla. The lacrimal groove lies between the two crests and contains the lacrimal sac