one of the precursors of disputed neurogenic thoracic outlet syndrome; a popular cause for upper extremity discomfort in the late 1930s and 1940s, based on the unproven concept that the lower trunk of the brachial plexus and the subclavian artery could be compressed in the intrascalene triangle by a hypertrophic scalenus anticus muscle, the compression in turn affecting the nerves to it and setting up a vicious circle; this concept was essentially abandoned in the 1950s, when actual causes, such as cervical radiculopathy and carpal tunnel syndrome, for upper extremity symptoms were appreciated, but resurrected in the 1980s, without attribution, as etiology for upper plexus type of disputed neurologic thoracic outlet syndrome.