No recurrent tumor could be documented, although patient 2 had residual tumor around the subclavian vessels
and brachial plexus after radiotherapy, with no signs of growth according to postoperative MRI scans over follow-up of 120 months.
During routine anatomical dissection of the supraclavicular and infraclavicular regions on the left side of an adult male cadaver at Department of Anatomy, Medical College, Universidad del Salvador, Buenos Aires, Argentina, we observed a supernumerary muscle that was attached, anteriorly, to the first costal cartilage and ran posteriorly and laterally crossing over the brachial plexus and subclavian vessels to end inserted on the fascia of the posterior surface of the serratus anterior muscle between its first two digitations, about 15 mm medially to the suprascapular notch (coracoid notch).
Supraesc M.: Supraspinatus muscle; Suprascap Nv.: Suprascapular nerve; Brachial Px.: Brachial plexus; Subclav V.: Subclavian vessels; Subclavian M.: Subclavius muscle.
Also, 28 patients had abnormal Doppler study showing decreased flow in the subclavian vessels. After diagnosis, all the patients were subjected to surgery under general anesthesia through the trans-axillary approach.
Out of 28 patients who had abnormal Doppler study (subclavian vessel compression), only 2 confirmed to have delay in flow on subclavian vessels on hyperabduction during postoperative follow-up.
During exposure of posterior triangle of neck, we observed long thin belly of a muscle superficial to brachial plexus and subclavian vessels
, which shared a common origin with subclavius muscle anteriorly, while posteriorly this muscle was attached to superior angle of scapula, medial to the attachment of inferior belly of omohyoid.
All the muscles regardless of their attachment on scapula and their innervation run superior to the subclavian vessels
and brachial plexus hence causing compression syndromes.
This condition frequently leads to thoracic outlet syndrome, a set of symptoms that may be caused by compression on the brachial plexus and on the subclavian vessels
in the region of the thoracic outlet.
The sternocleidomastoid muscle was retracted, thereby exposing the anomaly along with the subclavian vessels
and the brachial plexus.