Thoracic outlet syndrome (TOS) is a medical condition characterized by the compression of the nerves, blood vessels, or both as they pass through the thoracic outlet. The thoracic outlet is the narrow space between your collarbone (clavicle) and your first rib. The compression of these structures can lead to a variety of symptoms and can be classified into three main types:

● Neurogenic TOS: This is the most common type of TOS and occurs when the brachial plexus (a network of nerves that control the arm and hand muscles) is compressed. Symptoms can include pain, numbness, tingling, and weakness in the arm and hand.

● Arterial TOS: In this type of TOS, the subclavian artery, which supplies blood to the arm, is compressed. This can lead to reduced blood flow to the arm, causing symptoms such as coldness, color changes, and pain in the arm or hand, especially during physical activity.

● Venous TOS: Venous TOS occurs when the subclavian vein, which carries blood from the arm back to the heart, is compressed. This can lead to swelling, pain, and discoloration of the affected arm, and it is often associated with blood clots in the veins (deep vein thrombosis).

Common causes of thoracic outlet syndrome include:

● Congenital anatomical abnormalities that result in a narrower thoracic outlet.

● Poor posture.

● Repetitive arm and shoulder movements, such as those associated with certain jobs or sports.

● Trauma or injury to the shoulder or neck.

● Muscle imbalances or tightness in the neck and shoulder region.