The cervical vertebrae are recognized mainly by the presence of the foramen transversarium, which is crossed by the vertebral artery and vein, accompanied by sympathetic fibers. The main objective of this study was to observe and describe the anatomy and variations in the foramen transversarium. 121 cervical vertebrae were analyzed, including the macroscopic characteristics, shape and diameter and presence of the foramen transversarium, as well as the accessory foramen transversarium. All cervical vertebrae presented the foramen transversarium, with a mean diameter of 5.60 mm and a mean diameter of 4.40 mm on the right and 5.92 mm - 5.56 mm on the left, respectively. With regard to shape classification according to Taitz et al. (1978), 90.08 % presented the same shape on both sides, and 9.91 % had different shapes. The presentation of the different shapes was as follows: shape 1 41.32 %; shape 2 4.13 %; shape 3 18.8 %; shape 4 14.04 %; and shape 5 12.39 %. Regarding the presence of accessory foramen transversarium, 17.35 % of the vertebrae presented it, 66.6 % unilateral, 57.14 % on the right side and 42.85 % on the left side. Osteophytes, were presented in 5.7 %. The anatomical knowledge of these variations is useful for spine surgeons in preoperative planning and for preventing vertebral vessel and sympathetic nerve injuries during cervical surgical approaches.
KEY WORDS: Cervical vertebra; Foramen transversarium; Accessory foramen; Vertebral artery.