Orbit and Cavernous Sinus - LO 1

1. What are the bones forming the bony orbit? Identify the major foramina, fissures, and fossae associated with the orbit and what is transmitted through these structures.

The bony orbit is formed by seven bones, and form a pyramidal-shaped space. The bony orbit can be divided into four areas: roof, medial and lateral walls, and floor.

Roof:

• • Formed mostly by the frontal bone and a minor portion of the sphenoid towards the apex

    • Lacrimal fossa (for lacrimal gland)

Medial wall:

• • The frontal bone forms the superior portion of the medial wall

  • From anterior to posterior:

    • Maxilla: frontal process of maxilla; will form anterior portion of portion of lacrimal fossa (fossa of lacrimal sac)

    • Lacrimal bone: entire bone; will form posterior portion of lacrimal fossa (fossa of lacrimal sac)

    • Ethmoid bone: forms majority of medial wall

    • Sphenoid: towards the apex

Lateral wall:

• • Zygomatic bone anteriorly

  • Sphenoid posteriorly

Floor:

• • Maxilla: majority of floor

  • Zygomatic bone: anterolaterally

  • Palatine bone: posteromedially

Bony structures

• • Optic canal

    • Optic n. (CN II) & ophthalmic a.

  • Superior orbital fissure

    • Oculomotor n. (CN III), trochlear n. (CN IV), branches of ophthalmic n. (V1), abducens n. (CN VI), and superior ophthalmic v.

  • Inferior orbital fissure

    • Infra-orbital n. & zygomatic n. (V2)

    • Connection between pterygopalatine fossa & orbit