Rare bilateral origin variations of the suprascapular arteries

Shayan A Memar, Jeffrey M Alli

Abstract

A bilateral branching variation of the Suprascapular Artery (SA) was observed in a 75- year-old female cadaver during a routine dissection as a part of the spring 2018 anatomy course. Bilaterally, the SA did not arise from the thyrocervical trunk as it is commonly observed. On the right, the SA originated 13.6 mm from the beginning of the internal thoracic (mammary) artery, a branch of the first part of the right subclavian artery. It traveled further anterior to the lower insertion part of the anterior scalene muscle, lateral to the phrenic nerve, posterior to the medial third of the clavicle and anterior to the distal part of the subclavian artery and brachial plexus. It then crossed over the above structures to meet with the suprascapular nerve and continued along its normal route to the suprascapular notch. On the left, the SA and internal thoracic artery shared a common origin on the first part of the left subclavian artery, and then coursed anterior to the phrenic nerve and distal attachment of the anterior scalene muscle. Later, it followed a similar route as the right SA to the suprascapular notch. On both sides, the SA traveled above the superior transverse scapular ligament, whereas the suprascapular nerve passed below it. The presented anatomical variations of the suprascapular arteries are very rare and are clinically important for making accurate diagnoses, treating clavicle fractures as well as safely performing surgical procedures such as coronary bypass surgery.