The thoracic outlet is a small opening between the neck and shoulder that allows a variety of nerves and blood vessels to pass safely from the neck to supply the arm, chest, and shoulder blade. As this can be quite a small space, any narrowing can cause these structures to become compressed and irritated. This phenomenon is commonly referred to as thoracic outlet syndrome. This space can become compromised through trauma to the neck, overuse or repetitive stress to the arm, or the presence of an extra rib in the neck.
