Suboccipital segment of the vertebral artery: a cadaveric study.

OBJECTIVE To study the course, relationships, branches and possible anomalies of the vertebral artery in the suboccipital region in adult Indian cadavers. MATERIALS AND METHODS Twenty-one suboccipital segment vertebral artery specimens from embalmed, Indian adult cadavers were dissected and studied. Dissection was performed using microsurgical instruments and was carried out from the skin up to the vertebral artery in layers. The course, relationships and the branches of the vertebral artery were studied and measurements were taken using Vernier calipers. The readings obtained were corroborated with the measurements derived from the digital images using a computer. OBSERVATIONS All the vertebral arteries had a tortuous course and were covered with rich venous plexuses. None of the specimens had an anomalous course. The artery was divided into a vertical segment (Vv) between C2 and C1 vertebra and a horizontal segment (Vh) from the C1 transverse foramina to its dural entry. The mean diameter of the artery was 4.8 mm. The shortest distance of Vv segment from the dural tube was 16.1 mm, and the distance from the C2 ganglion was 7.2 mm. The average length of the Vv segment was 15 mm and the average length of the Vh segment was 35.6 mm. The average of the shortest distance between the vertebral artery and the midline was 13.4 mm. CONCLUSION The vertebral artery has a tortuous course and is prone to accidental iatrogenic injury, which can result in devastating neurological sequelae depending on contralateral vertebral artery flow. A thorough anatomical knowledge of this segment is essential for the surgeon who intends to operate in this area.