HN [6: Orbit]

Eye

Also known as the globe; organ for vision within the orbit.

Orbit

Bony cavity containing the eye, muscles, nerves, fats, and blood vessels.

Lamina Papyracea

Thinnest part of the medial wall prone to infection spread.

Lateral Wall

Thickest and strongest wall of the orbit.

Lateral Orbital Tubercle

A prominent bony landmark on the lateral wall that serves as an attachment site for eye tendons and ligaments.

Superior Orbital Fissure

Gap between the greater and lesser wings of the sphenoid bone transmitting CN III, IV, VI, V1, and the superior ophthalmic vein.

Annulus of Zinn

Fibrous ring at the orbital apex serving as the common origin for the four recti muscles.

Infraorbital Nerve

Sensory branch of CN V2 passing along the orbital floor to supply the lower eyelid, cheek, and upper lip.

Nasolacrimal Duct

Channel running through the nasolacrimal canal that drains tears into the nasal cavity.

Optic Canal

Passage for the optic nerve and ophthalmic artery.

Ophthalmic Artery

Primary arterial branch off the internal carotid artery supplying the orbit.

Central Retinal Artery

Key branch of the ophthalmic artery supplying blood directly to the inner retina.

Superior Ophthalmic Vein

Major vein draining the orbit through the superior orbital fissure into the cavernous sinus.

Lacrimal Gland

Tear

Nasolacrimal Duct

Channel that drains tears into the nasal cavity.

Eye

Organ constituting a quarter of the total face area.

Orbit

Bony cavity containing globes, extraocular muscles, nerves, fats, and blood vessels.

Orbit

Pear

Orbit

Provides protection to the globe without compromising the visual field.

Roof (superior), floor (inferior), lateral, and medial

Orbital Walls

Medial

Orbital Wall: Parallel

Medial

Orbital Wall: Separated by 25 mm in an average adult

Lateral

Orbital Wall: Forms an angle of approximately 45 degrees with the medial plane

Lateral

Orbital Wall: Widest dimension is about 1 cm behind the anterior rim

Frontal bone, Lesser wing of the sphenoid bone

Components of the orbital roof

Lacrimal gland fossa

Landmark of the orbital roof that houses the lacrimal gland

Trochlea

Pulley for the superior oblique tendon

Supraorbital foramen

Transmits the supraorbital vessels and branches of the frontal nerve

Zygomatic bone, Greater wing of the sphenoid bone

Components of the lateral orbital wall

Lateral orbital wall

Thickest and strongest wall of the orbit

Zygomaticofrontal suture, Lateral orbital tubercle of Whitnall

Landmarks of the lateral orbital wall

Lateral orbital tubercle of Whitnall

Attachment site for important orbital tendons and ligaments

Ethmoid, Lacrimal, Maxillary, Sphenoid bones

Components of the medial orbital wall

Frontoethmoidal suture

Important landmark of Medial wall that approximates the level of the cribriform plate, ethmoidal roof, and floor of the anterior cranial fossa

Lamina papyracea

Thinnest wall of the orbit

Ethmoid sinus, Sphenoid sinus, Nasal cavity

Adjacent structures associated with the medial orbital wall that allow infection to spread into the orbit

Maxillary, Palatine, Zygomatic bones

Components of the orbital floor

Infraorbital groove and canal

Contains the infraorbital artery and nerve, a branch of the maxillary division of the trigeminal nerve

Maxillary sinus

Adjacent structure of the orbital floor

Posteromedial part of the orbital floor

Most commonly fractured area in a direct blow to the eye

Ecchymosis

Sign that should raise suspicion for an orbital blowout fracture after an eye injury

Enophthalmos

Sinking in of the eye following an orbital blowout fracture

Hypoesthesia

Diminished sensation following an orbital blowout fracture

Diplopia

Double vision following an orbital blowout fracture

Implant

Used in orbital blowout fracture repair to support the prolapsed structure and restore the integrity of the orbital floor

Hypoesthesia

Expected postoperative complication of orbital blowout fracture repair due to likely damage to the infraorbital nerve within the infraorbital canal; most sensation recovers over time