Mete Büyükertan; Demet Terzi & Hüseyin Avni Balcıoglu

Accessory transverse foramen (ATF) is a rare anatomical variation of the cervical vertebrae that can alter the course of the vertebral artery, and this may lead to vascular and neurological complications. The existence, morphological diversity and clinical significance of ATF have been studied in different populations. This review aims to emphasize the importance of ATF in terms of diagnostic imaging and surgical procedures by examining its embryological origins, morphological variations and clinical significance in detail. In this context, a comprehensive literature review including osteological, radiological and clinical studies including the incidence, classification and associated risks of ATF was conducted. It was determined that ATF is most frequently seen between C1 and C6 vertebrae and has a prevalence rate ranging from 1.6 % to 22.7 %, depending on the population. Morphologically, ATF can be unilateral or bilateral, open or closed and can be found in different shapes such as round, oval or irregular. It has been determined that closed ATFs can occlude vascular pathways and cause neurological symptoms such as migraine, dizziness and vertebrobasilar insufficiency related to vertebral artery compression. Preoperative detection of this variation is of great importance for surgical planning and advanced radiologic techniques such as computed tomography and magnetic resonance angiography are preferred for this purpose. Understanding the anatomical variations of ATF is of great importance especially for spinal surgeries and vascular evaluations. Preoperative imaging and awareness of the risks associated with ATF are critical requirements to prevent surgical complications and increase surgical success.

KEY WORDS: Accessory transverse foramen; Cervical vertebra; Vertebral artery; Anatomical variation.

BÜYÜKERTAN, M.; TERZI, D. & BALCIOGLU, H. A. Accessory transverse foramen. Int. J. Morphol., 43(4):1267-1272, 2025.