Superior orbital fissure !

The superior orbital fissure is a slit at the back of the eye socket; it carries the nerves that move the eye and the ophthalmic branch of the trigeminal nerve.

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What it is

A slit at the back of the eye socket.

What it does

Carries the nerves that move the eye (III, IV, VI) and V1.

Key facts

Where: Between the greater and lesser wings of the sphenoid
Function: Transmits III, IV, V1 (lacrimal, frontal, nasociliary), VI and the superior ophthalmic vein

Relations

Contents: Lacrimal, frontal and nasociliary nerves (V1); oculomotor (III), trochlear (IV) and abducens (VI) nerves; superior ophthalmic vein and often the inferior one; sympathetic fibres and a small meningeal artery
Above: Lesser wing of the sphenoid bone, its upper border, with the frontal lobe above
Below: Greater wing of the sphenoid bone; just below its medial end the foramen rotundum, and in front the inferior orbital fissure
Medial: Body of the sphenoid; the optic canal above and medial, separated by the optic strut
Behind: Cavernous sinus, whose nerves run forward into it and whose blood arrives through the ophthalmic veins
In front: Orbital apex, where the four rectus muscles arise from the common tendinous ring bridging the medial part of the fissure

How to find it

It cannot be felt. Looking into the apex of a dry orbit, it is the slit between the lesser wing above and the greater wing below, lateral to the optic canal and wider at its medial end. Coronal CT shows it opening laterally from the orbital apex.

Examination

Eye movements, lid height, pupil size and forehead sensation, plus visual acuity, colour vision and the swinging-flashlight test: III, IV, VI and V1 deficits with a normal optic nerve point to the fissure
Corneal reflex: lost on that side when the nasociliary nerve (V1) is involved

On imaging

Thin-slice CT shows fractures of the sphenoid wings and narrowing of the fissure; contrast MRI with fat suppression shows inflammation, tumour or infection spreading between the orbital apex and the cavernous sinus.

Clinical notes

Causes include fractures of the lateral orbital wall or zygomatic complex, tumours, granulomatous inflammation (Tolosa–Hunt syndrome), herpes zoster and invasive fungal sinusitis
The superior ophthalmic vein carries blood from the face and orbit back through it to the cavernous sinus, a route for spreading infection
In a carotid–cavernous fistula the superior ophthalmic vein, which passes through the fissure, fills with arterial blood and looks enlarged on CT or MRI; it can also serve as a route to reach and close the fistula from within the vein

Memory aid

Order through the fissure, roughly top to bottom: «Live Frankly To See Absolutely No Insult» (Lacrimal, Frontal, Trochlear outside the ring; Superior division of III, Abducens, Nasociliary, Inferior division of III inside it).

Test yourself

Think of the answer, then tap the question to see it.

Which nerves pass through the superior orbital fissure inside the common tendinous ring, and which outside it?

Inside: both divisions of III, the nasociliary nerve and VI. Outside, above: the lacrimal and frontal nerves, IV and the superior ophthalmic vein.

What are the features of superior orbital fissure syndrome, and why is vision spared?

Palsy of III, IV and VI, ptosis, numb forehead (V1) and proptosis; vision is spared because the optic nerve runs in its own canal.

How do orbital apex syndrome and a cavernous sinus lesion differ from superior orbital fissure syndrome?

Add optic nerve loss and it is orbital apex syndrome; add V2 cheek numbness (often with a Horner pupil) and a cavernous sinus lesion is more likely.

Why can the superior oblique keep working after a block injected inside the muscle cone?

The trochlear nerve (IV) passes through the superior orbital fissure outside the common tendinous ring.

Why is the superior orbital fissure a route for spreading infection?

The superior ophthalmic vein carries blood from the face and orbit through it back to the cavernous sinus.

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Educational information, not medical advice. For any symptom, see a health professional.

Its names

Official Latin (TA2): fissura orbitalis superior TA2 488
Official Spanish (DeCS): Fisura orbitaria superior
English (TA2): Superior orbital fissure
Also called: fissura orbitalis cerebralis

V1 ophthalmic

Sources: Terminologia Anatomica (TA2); Orbital Apex Syndrome; Anatomy, Head and Neck, Skull Foramen.

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Representative model, for educational purposes only.