Thoracic outlet syndrome
What is thoracic outlet syndrome?
Thoracic outlet is a syndrome caused by injury of the neck musculature or tightening, especially since the muscles most commonly involved are accessory muscles of respiration (anterior and middle scalenes, and pectoralis minor), labored breathing can also bring about this condition. It can also occur from auto-accidents and chronic poor posture. The most commonly involved muscles are the anterior and middle scalenes (depicted in diagram on left). These muscles, if injured or become tight, can impinge a plexus of nerves called the brachial plexus as it comes through a narrow space between these muscles. When this happens, you will start to get numbness or pins and needles down the arm and into the hand sometimes. Less commonly you can get a more serious version of thoracic outlet syndrome, true vascular TOS. Vascular TOS can be more serious due to it impinging the subclavian artery as it passes through these muscles as well and this will cause arm weakness when arms are placed overhead for prolonged periods (sleeping with arm up).
Other causes of TOS
Pectoralis minor muscle tightness can cause this syndrome as well because it is one of the muscles that will tighten down with the poor posture of rolling our shoulders forward all day. Look at the picture on the next page and notice that the pectoralis minor muscle goes right over top of the brachial plexus and if it gets tighter can compress the nerves in this plexus.
Cervical rib can cause TOS as well due to the fact that this extra rib forms on the 7th cervical vertebrae and will stretch the 8th cervical nerve as we do motions above the head. Cervical ribs are not common and are only present in about 1% of the population. This extra rib can be seen on x-rays of the neck or cervical spine.
Benefits of chiropractic care: as well as correcting underlying conditions that can lead to muscle shortening like facet syndrome, seeing a chiropractor for this condition would be beneficial to correct postural issues. Some of these issues would be fixing or working to correct rolled shoulder which is also known as upper-cross syndrome, and to work on anterior head carriage. Things that should be done to correct these is to strengthen weak postural muscles in the back of the neck, as well as stretch muscles that are directly compressing the nerves by prescribing specific stretches that target the individual muscle that is involved, as well as trigger point therapy, and perform spinal manipulation to increase joint mobility of the segments that have become strained or stressed from abnormal posture.
Written by: Christopher G. Stine, M.S., D.C.
Images from: Frank Netter Atlas of Human Anatomy 6th edition