What is thoracic outlet syndrome?

Narrowing of space: Thoracic outlet syndrome is narrowng of the space between the first rib and the anterior scalene muscle. The axillary vein and artery and brachial plexus nerve passes through this space. Narowing the space can pinch the artery, vein, nerve or all of the above. Also, a rare, abnormal cervical rib can cause the same problems.

Nerve and vascular: Nerves connecting the arm and the spinal cord pass into the chest through a tunnel termed the thoracic outlet. In close contact are blood vessels. The tunnel can become too narrow and compress the nerves and/or blood vessels, with attendant pain, numbness, weakness, tingling, change in arm color, and especial problems if the arm is elevated.

Shoulder Pain: Thoracic outlet syndrome (tos) manifests as chromic shoulder pain, frequent episodes of arm going "to sleep" at night while reclined, and tingling and crawling sensations radiating into the arm, often into the pinky side of the hand.  the traditional explanation is that nerves and arteries going from the neck spine and from the core (thorax) of the body are pinched by tight scalene muscles, which.