The optic foramen is the opening to the optic canal.

The superior surface of the sphenoid bone

Sphenoid bone

The sphenoid bone is an unpaired bone situated at the base of the skull in front of the temporal bone and basilar part of the occipital bone.The sphenoid bone is one of the seven bones that articulate to form the orbit...

 is bounded behind by a ridge, which forms the anterior border of a narrow, transverse groove, the chiasmatic groove

Chiasmatic groove

The superior surface of the body of the sphenoid bone is bounded behind by a ridge, which forms the anterior border of a narrow, transverse groove, the chiasmatic groove , above and behind which lies the optic chiasma of cranial nerve 2 .The groove ends on either side in the optic foramen, which...

 (optic groove), above and behind which lies the optic chiasma; the groove ends on either side in the optic foramen, which transmits the optic nerve

Optic nerve

The optic nerve, also called cranial nerve 2, transmits visual information from the retina to the brain. Derived from the embryonic retinal ganglion cell, a diverticulum located in the diencephalon, the optic nerve doesn't regenerate after transection.-Anatomy:The optic nerve is the second of...

 and ophthalmic artery

Ophthalmic artery

The ophthalmic artery is the first branch of the internal carotid artery distal to the cavernous sinus. Branches of the OA supply all the structures in the orbit as well as some structures in the nose, face and meninges...

 (with accompanying sympathetic nerve fibres) into the orbital cavity.

The left and right optic canals are 25mm apart posteriorly and 30mm apart anteriorly. They are funnel-shaped (narrowest anteriorly).