Anatomy of the Bony Orbit

Overview

• Presenter: Peter from Anatomy Zone
• Collaboration: Anatomy Zone and Teach Me Anatomy
• Focus: Anatomy of the Bony orbit (eye sockets)

Structure of the Bony Orbit

• General Shape: Pyramidal structure
  • Apex: Points posterior-medially into the optic fenestra
  • Base: Situated anteriorly, opens into the face (orbital rim)
• Symmetrical Cavities: Bilateral, encloses the eyeball and associated structures

Boundaries of the Orbit

• Formed by Seven Bones:
  • Anterior View:
    • Frontal bone (red)
    • Maxilla (purple)
    • Zygomatic bone (light blue)
    • Sphenoid bone (yellow)
    • Ethmoid bone (orange)
  • Medial Aspect:
    • Lacrimal bone (green)
    • Ethmoid bone (orange)
    • Palatine bone (dark blue)

Orbital Rim

• Superior Border: Frontal bone
• Medial Border: Frontal process of the maxilla
• Inferior Border: Zygomatic process of the maxilla and zygomatic bone
• Lateral Border: Frontal process of the zygomatic bone and the zygomatic process of the frontal bone

Components of the Bony Orbit

• Roof/Superior Wall: Formed by frontal bone and lesser wing of sphenoid
  • Separates orbit from the anterior cranial fossa
• Floor/Inferior Wall: Formed by maxilla, palatine, and zygomatic bones
  • Separates orbit from maxillary sinus
• Medial Wall: Formed by ethmoid, maxilla, lacrimal, and sphenoid bones
  • Separates orbit from ethmoid sinus
• Lateral Wall: Formed by zygomatic bone and greater wing of sphenoid
• Apex: Located at the optic canal, also known as optic foramen

Contents of the Bony Orbit

• Eyeballs and Associated Structures:
  • Extraocular muscles
  • Eyelids
  • Several nerves and blood vessels
• Nerves: Optic, oculomotor, trochlear, trigeminal, and abducens nerves
• Blood Vessels: Primarily receives blood from the ophthalmic artery
  • Venous drainage via superior and inferior ophthalmic veins

Pathways into the Orbit

• Optic Canal:
  • Transmits optic nerve and ophthalmic artery
  • Opens into the middle cranial fossa
• Superior Orbital Fissure:
  • Transmits several nerves (including lacrimal, frontal, trochlear, superior/inferior oculomotor, nasociliary, abducens) and the superior ophthalmic vein
• Inferior Orbital Fissure:
  • Separates lateral wall from the floor of the orbit
  • Transmits zygomatic branch of maxillary nerve, inferior ophthalmic vein, and sympathetic nerves

Additional Openings

• Nasolacrimal Canal: Drains tears from eye to nasal cavity, located on the medial wall
• Supraorbital and Infraorbital Foramina: Transmit small neurovascular structures
• Infraorbital Groove and Canal: Connects to the infraorbital foramen, path across the floor of the orbit

Resources

• Teach Me Anatomy: Additional anatomy articles
• Anatomy Zone: Videos and flashcards
• Anatomy Learning App: 3D models used for illustrations