Study of Foramen Transversarium: A Morphological Variation

Background: Foramen transversarium (FT) is the special foramen located on the cervical vertebrae’s left and right transverse processes (C1 to C7) containing the vertebral vessels and sympathetic plexus.1-3 It is an important and noticeable feature of the cervical vertebrae that occupies the sympathetic fibers, vertebral vein (VV), and vertebral artery (VA). Foramen transversarium gives passage to vertebral artery, vertebral vein and sympathetic plexus from inferior cervical ganglion while C7 vertebra transmits only the vein. The vertebrae of the cervical part and the proximal thoracic part of the human vertebral column are the area undergoing the most intense transformation during phylogeny, leading to many anatomical variations. Aim: Morphometric analysis of Foramen transversarium. Objectives: To Study Foramen Transversarium unilateral & Bilateral. Material and Methods: All the collected cervical vertebrae were examined macroscopically for the existence of the Foramen Transversarium in the 7th cervical vertebrae and the contents passing through it on both sides. All the cervical vertebrae were studied for the presence of more than one foramen and those with double foramen were photographed. In vertebrae with double foramen, the larger foramen was taken as the main foramen and the smaller foramen as the accessory foramen (AF). Digital vernier calipers of 0.01 mm precision were used for morphometric measurements. Vertebrae with this variation were photographed and noted. Results: Result of the 120 cervical vertebrae studied, 17 (14.1%) vertebrae were found to have double FT. Out of the 17 vertebrae, 14 vertebrae were typical and 3 were atypical cervical vertebrae. Among the 14 typical cervical vertebrae, 11 (78.5%) vertebrae had AF on the right side, 1 (7.1%) had on left side and 2 (14.2%) had bilateral AF. Among the three atypical cervical vertebrae, 2 (66.6%) had AF on the right side and 1 (33.3%) had bilateral AF. No AF was found in atlas and axis vertebrae. Conclusion: The present study has shown that Accessory Foramen is more common on the right side is smaller in size and is situated posterior to the main foramen. The knowledge of these variations will be useful in predicting variations in the course of the vertebral artery and will aid orthopedic surgeons for planning the posterior approach of cervical spines.