Whats thoracic outlet syndrome?

TOS: Tos involves the lower portion of the brachial plexus, where nerves from the neck pass through a tunnel into the chest on the way to the arm. The plexus can get trapped in the outlet area, and this event can cause pain, numbness, tingling, weakness, but can also affect blood vessels. On occasion, a congenital first rib can cause compression but trauma may also promote tos.

Compression: TOS is due to compression of the neurovascular structues of the thoracic outlet (subclavian vessels, brachial plexus) . The 1st rib, anterior and medial scalene muscles form a traingle through which the aforementioned structures exit the chest into the upper extremity. Compression occures for various reasons and the compression may be of the nerves or the blood vessels.