Vol.:(0123456789) 1 3 Surgical and Radiologic Anatomy (2021) 43:577–578 https://doi.org/10.1007/s00276-021-02679-9 LETTER TO THE EDITOR A terminological confusion: optic foramen or canal? Saliha Seda Adanir 1  · Orhan Beger 1  · İlhan Bahşi 1 Received: 12 October 2020 / Accepted: 2 January 2021 / Published online: 12 January 2021 © The Author(s), under exclusive licence to Springer-Verlag France SAS part of Springer Nature 2021 To the Editor, The article “Anatomic features of the cranial aperture of the optic canal in children: a radiologic study” was published by Ten et al. [13] lately in Surgical and Radiologic Anatomy. We wish this article may be an example for avoiding misuse of the "optic canal" and "the apertures of the optic canal" defnitions. Anatomical terminology has been the subject of consider- able dispute for many years. To put an end to these confu- sions and standardize anatomical terminology, International Anatomical Nomenclature Committee produced Nomina Anatomica. Later, Terminologia Anatomica was published by the Federative Committee on Anatomical Terminology, created by the International Federation of Associations of Anatomists [14]. Although both were designed to standard- ize anatomical terminology and avoid mess, there is still confusion regarding the nomenclature of some anatomical structures today [1]. One of these complexities is related to the nomenclature optic canal and optic foramen, both of which can be used interchangeably nowadays. The optic canal is located in the lesser wing of the sphenoid bone, between the orbit and cra- nial cavity, and is a canal through which the optic nerve, ophthalmic artery, dura mater, and sympathetic nerves pass [12]. This canal is clinically meaningful because of its neuro-arterial relations [6]. Due to this importance, the morphology of the optic canal and its relationship with sur- rounding structures have been evaluated in many studies [2, 6, 11]. In some articles and leading anatomy textbooks, the canal can also be defned as the optic foramen [3, 12]. Moreover, there are diferences in the defnition of the optic foramen in the literature. The cranial opening of the optic canal was accepted as the optic foramen in some studies, while the orbital opening as the foramen in another [2, 11]. Interestingly, the optic foramen is defned as the pyramid- shaped apex of the orbit in Gray’s Anatomy for Students [4]. The inconsistency between these nomenclatures is thought to be due to the lack of clear terms describing the optic canal and its orbital or cranial openings. Because of this confusion, we wanted to retrospectively examine the naming of the optic canal and optic foramen. In the frst edition of Gray’s Anatomy, published in 1858 [7], Die Anatomische Nomenclatur: Nomina Anatomica, published in 1895 [8], and The Basle Anatomical Nomen- clature, published in 1916 [9], the nomenclature of the optic canal was not passed, but the term optic foramen was used. In the following years, the same formation is named as the optic canal or optic foramen in the literature [3]. Then, in the Nomina Anatomica: Vergleichende Übersicht der Basler, Jenaer und Pariser Nomenklatur [Comparative overview of the Basiliensia, Jenaiensia, and Parisiensia Nomina Ana- tomica], published in 1957, it was observed that the terms foramen opticum (in the section of Basiliensia Nomina Ana- tomica) and canalis opticus (in the section of Parisiensia Nomina Anatomica) were both combined [10]. On the other hand, it was reported that the International Nomenclature Committee (1955) felt that its use should not be perpetu- ated, as it is never a foramen but always a short bony canal. Afterward, in the Terminologia Anatomica, published in 1998, the term optic foramen was not found and only optic canal was named [5]. In anatomical terminology, the terms foramen and canal are used to name diferent structures. For this reason, we think that using optic foramen and optic canal synonymously is a terminological mistake. On the other hand, we believe that it is not theoretically wrong to use the term “optic fora- men” for the cranial or orbital openings of the optic canal. However, naming both the optic canal and its openings as the optic foramen may cause confusion. In our opinion, the * İlhan Bahşi dr.ilhanbahsi@gmail.com Saliha Seda Adanir seda.adnr93@gmail.com Orhan Beger obeger@gmail.com 1 Department of Anatomy, Faculty of Medicine, Gaziantep University, Gaziantep, Turkey