Eur J Anat, 18 (3): 159-163 (2014)

Anatomical variations of the pre-transverse segment of the vertebral artery in Indian cadavers

Raveendranath Veeramani¹ and Nachiket Shankar²

¹Department of Anatomy, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER),Dhanvantri Nagar, Puducherry, India and ²Department of Anatomy, St. Johnâ??s Medical College, Bangalore, Karnataka, India

ABSTRACT Variations of the first segment (V1) of the vertebral artery (VA) are important to spine surgeons and radiologists. The present study was conducted to document the anatomical variations of the V1 segment and estimate side and gender differences, if any. The study was a cross-sectional analytical study performed on 33 adult cadavers (24 male and 9 female) of Indian origin. The V1 segment of 67 VA was dissected and the following parameters were noted: site of origin, level of entry into cervical spine, presence of tortuosity, length, external diameter and presence of hypoplasia. Side differences were estimated using the paired sample T test and Wilcoxon signed rank test. The independent sample T test and Chi square test were used to estimate gender differences. An unusual origin of the right VA from the thyrocervical trunk, in addition to the origin of the left VA from the arch of the aorta, was noted. Stenotic segments were observed in 4.5% of the VA. Rare levels of entry into the cervical column of the V1 segment of the VA included the foramen transversarium of C5 (4.5%) and C7 vertebra (2.5%). Nine per cent of V1 segments showed a high degree of tortuosity. The mean length and diameter of the V1 segments were 3.7±1.5 cm and 4.2±0.9 mm respectively. Hypoplasia was observed in 18% of the V1 segments. The mean length of the V1 was found to be significantly greater on the left side. Male cadavers had a significantly greater external diameter of V1. The knowledge of these variations of the V1 segment of the VA is imperative for the safe performance of anterior spine procedures.

Keywords: Vertebral artery, Pre-transverse segment, Anatomical variations