The accessory costotransverse foramen: a radioanatomical study

One hundred fifty-six anatomical specimens of cervical vertebrae and 55 C1 and 53 C2 vertebrae were examined for the presence of an accessory costotransverse foramen. We also reviewed 60 cervical spine computed tomographic (CT) scans. The variations of the costotransverse and accessory foramen are discussed. The frequency of the latter is 19% in the anatomical specimens and 45% in CT scans. The local anatomy and the excellent visualization on axial transverse CT are stressed.