Orbits: Anatomy & Routine Projections

Orbit

Bony cavity that contains and protects the eye

How many bones form each orbit?

7

Seven bones of the orbit

Frontal, sphenoid, ethmoid, maxilla, zygomatic, lacrimal, and palatine

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Optic foramen / optic canal

Opening at the apex of the orbit that allows passage of the optic nerve

Cranial nerve II, the optic nerve

Which cranial nerve passes through the optic foramen?

Optic foramen, II

The __ __ is passage for cranial nerve ___, which carries visual information

Superior orbital fissure

Opening between the greater and lesser wings of the sphenoid

superior

Cranial nerves III, IV, V1, and VI pass through the ___ orbital fissure

Superior

The ____ orbital fissure is for eye-movement nerves

Inferior orbital fissure

Opening in the inferior portion of the orbit

Inferior

Maxillary branch of cranial nerve V, V2 passes through the ___ orbital fissure

Inferior

____ orbital fissure = V2 / maxillary

Optic foramen, superior orbital fissure

_____ = CN II for vision; ______ = III, IV, V1, VI

Superior, inferior

____ = III, IV, V1, VI; _____ = V2

Sphenoid strut

Forms part of the lateral wall of the optic canal

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UP 30°, IN 37°

Long axis of orbit : Projects superiorly about ___ and medially about ___

Palatine bone

Small part of the posterior orbital floor

Frontal bone contribution to orbit

Forms much of the orbital roof

Maxilla contribution to orbit

Forms much of the orbital floor

Zygomatic bone contribution to orbit

Forms part of the lateral wall and floor

Ethmoid contribution to orbit

Forms much of the medial orbital wall

Lacrimal

_____ is a small bone in the medial wall of the orbit

Sphenoid contribution to orbit

Forms the posterior orbit and contains important orbital openings

for MRI

To check for metallic foreign bodies in or around the orbit