Background:  The typical feature of cervical vertebrae is presence of foramen transversarium  which exibit variations in the number, size, shape which may lead to various symptoms.The aim of the present study was to find the variations in the foramen  transversarium such as incidence of accessory foramen transversarium, different shape of  foramen transversarium and its clinical significance.

Material and Methods:  This study included 91 dried cervical vertebrae obtained from the Department of Anatomy, Govt Thiruvannamalai Medical college, Thiruvannamalai. All the cervical vertebrae were observed macroscopically for the presence of accessory foramina transversaria on both side. Also the shape and the direction of the main diameter of foramen transversarium were studied and classified into five types.

Results:  Among the 91 cervical vertebrae, accessory foramen transversarium observed only in 6 cervical vertebrae(6.6%).Out of this unilateral accessory foramen transversarium  found in 5 vertebrae(5.5%) and bilateral accessory foramen transversarium found only in one vertebrae(1.1%).Five different shapes of foramen transversarium were noted and Type 1(round) shape was the prominent (52.2%)

Conclusion:  The incidence of accessory foramen transversarium in the present study was 6.6%.Accessory foramen transversarium were smaller as compared to the normal foramen and more common in lower cervical vertebrae(C6,C7). Anatomical knowledge of these variations in foramen transversarium will be useful for radiologists in interpretation of x rays,CT,MRI scans of cervical region and also for neurosurgeons, vascular surgeons operating in this region.