Where is it located and how is it formed?
The superior orbital fissure is formed by the bony elements of the sphenoid bone (os sphenoidale). It is a space located between the lesser wings (alae minores) and greater wings.
The inferior surfaces of the lesser wings form the superior wall of the orbit (facies orbitalis), and posteriorly and medially they terminate in the anterior clinoid processes. The optic canal (canalis opticus) is located at the base of the lesser wing. The superior orbital fissure serves as a communication pathway between the middle cranial fossa (fossa cranii media) and the orbit (orbita).
What passes through the superior orbital fissure?
This opening is the entry point for nerves into the orbital cavity. It transmits motor nerves innervating the extraocular muscles and one sensory branch:
- The oculomotor nerve (n. oculomotorius) — cranial nerve III.
- Trochlear nerve (n. trochlearis) — cranial nerve IV.
- Abducens nerve (n. abducens) — cranial nerve VI.
- Ophthalmic nerve (n. ophthalmicus) — the first branch of the trigeminal nerve (cranial nerve V). It is exclusively sensory in function (sensoria). The peripheral processes of the trigeminal ganglion cells running within this nerve are involved in the perception of pain, temperature, and tactile sensation on the face.
Cranial nerves III, IV, and VI initiate movements of the eyeball by sending impulses to the muscular apparatus of the eye and eyelids: the levator palpebrae superioris, rectus, and oblique muscles of the eye. Normally, they ensure conjugate eye movements.
In addition to nerve trunks, the fissure transmits blood vessels:
- Superior ophthalmic vein (v. ophthalmica superior).
- Occasionally — anterior meningeal branches from the ophthalmic artery (r. meningeus anterior ex a. ophthalmica).
Topography and adjacent structures
The orbit communicates with the cranial cavity via the optic canal and the superior orbital fissure. The optic nerve (cranial nerve II) passes through the optic canal. In addition, the orbit communicates with the pterygopalatine and infratemporal fossae via the inferior orbital fissure (fissura orbitalis inferior).
From the cranial cavity side, the superior orbital fissure opens into the middle cranial fossa. Located in the same fossa are other important foramina for the exit of trigeminal nerve branches: the foramen rotundum (foramen rotundum) for the maxillary nerve (second branch) and the foramen ovale (foramen ovale) for the mandibular nerve (third branch).
Clinical significance
When anesthetizing tissues innervated by the second branch of the trigeminal nerve, the orbital approach may be used. In this technique, the needle is inserted in the region of the inferolateral angle of the orbit and advanced along the lateral wall posteriorly to a depth of 4–5 cm.
If the needle deviates and penetrates the superior orbital fissure, mechanical trauma to the wall of the cavernous sinus (sinus cavernosus) may occur. In the wall of this sinus, the oculomotor nerves run in close relation to the internal carotid artery. Damage to the sinus leads to the development of sinus thrombosis—a life-threatening complication.
Class and exam questions
Which cranial nerves exit the cranial cavity through the superior orbital fissure?
It transmits cranial nerves III (oculomotor), IV (trochlear), and VI (abducens), as well as the first branch of CN V—the ophthalmic nerve.
With which cranial cavities does the superior orbital fissure communicate?
It connects the middle cranial fossa with the orbital cavity.
Which branch of the trigeminal nerve passes through this fissure and what is its function?
The first branch of the trigeminal nerve—the ophthalmic nerve (n. ophthalmicus)—passes through the fissure. It is exclusively sensory in function.
Why is needle penetration into the superior orbital fissure dangerous during anesthesia?
This can cause mechanical trauma to the wall of the cavernous sinus, which poses a risk of developing a life-threatening complication: sinus thrombosis.
What else to study on this topic
- Middle cranial fossa (Fossa cranii media)
- Ophthalmic nerve (Nervus ophthalmicus)
- Cavernous sinus (Sinus cavernosus)
- Sphenoid bone (Os sphenoidale)
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