The vertebral artery (VA) arises from the superior surface of the first part of the subclavian artery medial to the scalenus anterior muscle
It is usually attached to the first rib, close to the insertion of scalenus anterior muscle
The key points in both the approaches are (1) complete resection of bony, cartilaginous, and fibrous parts of (2) complete resection of the scalenus anterior muscle
at the scalene tubercle on the first rib and (3) arterial exploration and reconstruction.
The scalenus anterior muscle
pulls the lateral portion of the first rib proximally and posteriorly and the scalenus medius muscle pulls the medial portion of the first rib proximally and medially.
Absence of scalenus anterior muscle
. Acta Medica Okayama 57 (3): 159-161.
Daseler and Anson came across a bilateral malposition of subclavian artery both situated anterior instead of posterior to scalenus anterior muscle
It descended downwards and laterally to merge with the tendon of scalenus anterior muscle towards its insertion.
These anomalous muscular slips sometimes arose from scalenus medius muscle and ran into scalenus anterior muscle or vice-versa (Yamamoto, 1992).