A description is made on narrow spaces through which the brachial plexus and subclavian-axillary vessels run from the cervical spine up to the inferior border of the pectoralis major muscle. The spaces are: "Pleural suspensory Apparatus", interscalene spaces (vascular and neural), costo-clavicular, clavi-pectoral, retro-pectoralis minor, pre-humeral head, median nerve roots compass, pre-scalene space. Compressions with or without cervical rib, static or dynamic, are also described. Downward migration of shoulder girdle and muscle variations are analyzed. Forced positions which may produce compressions are also considered (downward pull, abduction + retraction, hyperabduction).