Unilateral absence of the thyrocervical trunk with multiple subclavian arterial variations and a suprascapular artery traversing the brachial plexus: a cadaveric case report.

PURPOSE: Understanding anatomical variations in the branching pattern of the subclavian artery (SA) is critical to reducing complications during surgical and interventional procedures involving the neck and shoulder regions. This cadaveric study reports a rare combination of vascular anomalies involving the branches of the SA.

METHODS: Bilateral dissections of the neck, shoulder, and upper back were performed on a 71-year-old Caucasian male donor to document the origin, course, and distribution of the branches of the SA.

RESULTS: Multiple unilateral variations were observed on the right side of the donor. The first variation noted was the absence of the thyrocervical trunk, with its typical branches showing variable origins. Inferior thyroid artery originated with the vertebral artery from the thyrovertebral trunk, representing the second variation. Transverse cervical artery was completely absent, representing the third variation. The fourth variation was the dorsal scapular artery serving as the primary blood supply to the trapezius muscle. The suprascapular artery (SSA) originated from the axillary artery and coursed posteriorly between the anterior divisions of the upper and middle trunks, immediately superior to their union to form the lateral cord, representing the fifth variation. Lastly, the SSA entered the supraspinous fossa beneath the superior transverse scapular ligament, accompanied by the suprascapular nerve, representing the sixth variation.

CONCLUSION: This case demonstrates a unique combination of six arterial variations that, to our knowledge, have not been previously reported together. Awareness of such variants is important for surgical planning and may help reduce intraoperative complications in head, neck, and shoulder procedures.