Description
In thoracic outlet syndrome (TOS), nerves or blood vessels in the thoracic outlet are compressed or irritated.
Introduction
The thoracic outlet is the space between your neck and chest, also called the thoracic inlet or superior thoracic aperture. This area serves as a pathway for important structures, including the brachial plexus (nerves that travel from your neck to your armpit), as well as the subclavian artery and subclavian vein.
Typically, your thoracic outlet has enough space for nerves and blood vessels to move freely. Changes in your body’s structure or injuries can sometimes make this space smaller. When that happens, nearby bones or muscles in your chest may put pressure on the nerves or blood vessels, causing compression. This can lead to pain, strange sensations like tingling or numbness and other symptoms in your upper body.
Types
Following are the three types of TOSs:
- Neurogenic TOS: This is the most prevalent form. In this case, a cluster of nerves known as the brachial plexus becomes compressed. These nerves originate from the spinal cord and are responsible for controlling muscle movement and sensations in your shoulder, arm and hand.
- Venous TOS: This type occurs when one or more veins under the collarbone become compressed and damaged, potentially resulting in blood clots.
- Arterial TOS: This is the rarest type. It occurs when an artery located beneath the collarbone becomes compressed, potentially causing damage to the artery. This can result in a bulge, referred to as an aneurysm, or the development of a blood clot.


