What is Thoracic Outlet Syndrome?

The 'Thoracic Outlet' is a complex area of anatomy, and it is easier to see where it is located in the following images, as this will help to understand how nerves, arteries and veins in the area are affected, as well as muscle tissue.

Thoracic Outlet or TOS can affect the subclavian artery, the subclavian vein, and then the nerves that supply the brachial plexus. This means that there are three different types of TOS - Neurological TOS or NTOS, that affects up to 90% of the clinical population, ATOS which is arterial TOS and the least common and most serious is VTOS, which is the most serious and can lead to blood clots [ATOS can too, although the subclavian artery may be occluded or blocked partly by the actions of neural receptors that cause it to contract].