21st February 2024

Orbital Fissures and Foramina

Optic Canal

The optic canal, within the lesser wing of the sphenoid bone, serves as a crucial passage for the optic nerve (cranial nerve II) and the ophthalmic artery. Any compression or damage to the optic canal can lead to vision impairment. 

Superior Orbital Fissure

Positioned between the greater and lesser wings of the sphenoid bone, the superior orbital fissure accommodates several critical structures, including cranial nerves III (oculomotor), IV (trochlear), and VI (abducens), along with the ophthalmic division of the trigeminal nerve (cranial nerve V1). These nerves are responsible for eye movement, pupil constriction, and sensory innervation to various parts of the face and eye. A lesion or compression within the superior orbital fissure can result in debilitating eye movement disorders or sensory deficits.

Inferior Orbital Fissure

The inferior orbital fissure is located at the intersection of the sphenoid, maxilla, and zygomatic bones. It provides a pathway for branches of the maxillary nerve (cranial nerve V2) and blood vessels. Disorders affecting this fissure can lead to sensory disturbances in the face and orbit, particularly the lower eyelid and cheek.

Ethmoidal Foramina

The ethmoidal foramina, found in the ethmoid bone, permit the passage of anterior and posterior ethmoidal vessels and nerves. These structures play a role in the sensory innervation and vascular supply to the nasal cavity and ethmoidal air cells. Blockages or damage to these foramina can disrupt normal nasal physiology and potentially affect the eye due to their proximity.

Supraorbital and Infraorbital Foramen

The supraorbital foramen is the small opening at the superior orbital margin in the frontal bone just below the superciliary arches that transmits the supra-orbital nerve, artery and vein. The infraorbital foramen is within the maxillary bone. It is the anterior opening of the infraorbital canal, which is the anterior continuation of the infraorbital groove, which runs through the floor of the orbit.