Eyelids and Adnexa: Bones and Foramina of the Orbit

The orbit, also known as the eye socket, is a bony structure that houses the eyeball and its associated structures. It plays a crucial role in protection, movement, and functionality of the eye. The bony anatomy of the orbit includes several bones and foramina that allow nerves and blood vessels to pass through.

Bony Structure of the Orbit

The orbital cavity is composed of seven bones:

• Frontal Bone – forms the superior orbital rim.
• Sphenoid Bone – contributes to the posterior wall.
• Zygomatic Bone – forms part of the lateral wall.
• Maxilla – forms the inferior portion.
• Lacrimal Bone – located medially.
• Ethmoid Bone – contributes to the medial wall.
• Palatine Bone – a small portion of the orbital floor.

Major Foramina of the Orbit

Several foramina allow passage for critical structures:

• Optic Canal – Passage for the optic nerve (CN II) and ophthalmic artery.
• Superior Orbital Fissure – Transmits cranial nerves III, IV, V1, VI, and ophthalmic veins.
• Inferior Orbital Fissure – Allows passage of infraorbital nerve and vessels.
• Supraorbital Foramen – Transmits the supraorbital nerve and artery.
• Infraorbital Foramen – Allows the infraorbital nerve to exit.

Clinical Significance

Understanding the bony anatomy and foramina of the orbit is critical for diagnosing and treating various medical conditions such as orbital fractures, nerve compression syndromes, and vascular disorders. Surgical approaches often require detailed anatomical knowledge to avoid complications.