Thoracic outlet syndrome is actually a collection of syndromes brought about by abnormal compression of the neurovascular bundle by bony, ligamentous or muscular obstacles between the cervical spine and the lower border of the axilla. First of all a syndrome is defined as a group of signs and symptoms that collectively characterize or indicate a particular disease or abnormal condition. The neurovascular bundle which can suffer compression consists of the brachial plexus plus the C8 and T1 nerve roots and the subclavian artery and vein. The brachial plexus is the network of motor and sensory nerves which innervate the arm, the hand, and the region of the shoulder girdle. The vascular component of the bundle, the subclavian artery and vein transport blood to and from the arm. the hand. the shoulder girdle and the regions of the neck and head. The bony, ligamentous, and muscular obstacles all define the cervicoaxillary canal or the thoracic outlet and its course from the base of the neck to the axilla or arm pit. Look at the scheme of this region and it all becomes more easily understood. Compression occurs when the size and shape of the thoracic outlet is altered. The outlet can be altered by exercise, trauma, pregnancy, a congenital anomaly, an exostosis, postural weakness or changes. Thoracic outlet syndrome has been described as occurring in a diverse population. It is most often the result of poor or strenuous posture but can also result from trauma or constant muscle tension in the shoulder girdle. The first step to beginning any treatment begins with a trip to the doctor. Make a list of all of the symptoms which seem to be present even if the sensations are vague. Make a note of what activities and positions produce or alleviate the symptoms and the time of day when symptoms are worst. Also, note when the symptoms first appeared. This list is important and should also include any questions one may have.