[Applied anatomy of the optic nerve]

This review systematizes data on the anatomy of the optic nerve from an applied perspective. It describes in detail the embryogenesis, structure, and topography of each of its four segments (intraocular, intraorbital, intracanalicular, and intracranial). Considerable attention is paid to variations in the relationship between the optic nerve and the sphenoid sinus, taking into account the structural features of the latter. The review presents variations in the frequency of optic nerve types according to M.C. DeLano et al. (depending on their relationship with the sphenoid sinus), including in the presence of optic canal dehiscence, Onodi cells, and pneumatization of the anterior clinoid process; it also describes variants of the topography of the sphenoid sinus and the presence of additional septa within it.