Thoracic outlet syndrome is a condition in which the nerves or vessels behind the collar bone (clavicle) become compressed or stretched. Arm pain, weakness, or numbness often result.
Symptoms typically occur with lifting the arms to shoulder level or other positions that put pressure on the nerves and vessels behind the collar bone. Treatment includes stretching and strengthening exercises as well as avoiding activities that cause symptoms. In rare cases surgery is needed to relieve the nerve compression.
WebMD Medical Reference from Healthwise