Anatomy of scalenovertebral triangle: A vade mecum for clinicians.

Objective Of The Study: The thorough anatomical knowledge of scalenovertebral triangle or Triangle of the vertebral artery and its contents is crucial in various neurosurgical procedures such as scalenotomy, stellate ganglion block, direct isolation of proximal vertebral artery and proximal brachial plexus repair.

Material And Method: Thirty scalenovertebral triangles of known age and sex were dissected. The morphometry of the triangle and stellate ganglion was done. Various relevant distances were measured for topographical location of neurovascular structures especially stellate ganglion and vertebral artery within the triangle.

Results: The mean height and width of the scalenovertebral triangle was 21.7+5.1mm and 19.4+4.4mm respectively. Vertebral artery originated from subclavian artery within the triangle except in one case (left side) where it originated from aortic arch. The mean minimum distance of stellate ganglion from phrenic nerve, scalenus anterior and vertebral origin was 12.6+4.5mm, 12.26+4mm and 2.3+1.3mm respectively.

Conclusions: The origin and proximal part of vertebral artery may not be present within the scalenovertebral triangle, thus topographic anatomy of the stellate ganglion is also affected and may cause complications during stellate ganglion block. Stellate ganglion is never located in the lateral or upper third of triangle. Occasionally, the phrenic nerve may cross the triangle, making it unsafe during stellate ganglion block.