Anatomy, Head and Neck, Inter-scalene Triangle

The inter-scalene triangle is a region of the neck that holds fundamental structures to the upper extremity function. The triangle is composed of two muscles and the first rib. The two neck muscles are the anterior and middle scalenes. The angle between the muscles can be as little as zero degrees, which can lead to complications. Regardless, this triangle is integral for upper extremity anesthesia because it identifies the location of the brachial plexus. The brachial plexus is the source of the nerves of the rest of the arm and is fundamental in the extremity’s functionality. Issues with this plexus, specifically at the level of the inter-scalene triangle, can be detrimental to the quality of life of a patient; these issues are otherwise known collectively as thoracic outlet syndrome. Other problems can occur with the vascular structures of the triangle, specifically the subclavian artery and the neighboring subclavian vein. Occlusions can lead to aneurysms and weakness of the arm.