Thoracic Outlet Syndrome (TOS)

Do you suffer from numbness or tingling in your arms and hands?

The thoracic outlet is the opening at the upper margin of the rib cage. See picture below.

Thoracic Outlet Syndrome Revolution Health Centre Numbness in hands and arms massage colac camperdown

Thoracic outlet syndrome is not a single condition, but the term encompasses several variations of nerve or vascular compression near the base of the neck and upper rib cage.

The condition is generally a chronic dysfunction due to poor posture or faulty work practices such as slumping over a computer, or carrying heavy backpacks with shoulder straps. Head forward posture with an exaggerated upper thoracic kyphosis, and internally rotated humerus are usually seen in cases of TOS.

Bad-Posture-Examples thoracic outlet syndrome revolution health centre numbness in arms and hands massage colac camperdown

TOS is mostly a nerve compression syndrome involving the brachial plexus (nerve branch coming out of the cervical area of the spine) and not a vascular disorder, but in some cases the blood vessels can be affected.

The Brachial Plexus:

The cervical nerves appear out the cervical vertebrae, and converge into a rope-like bunch of nerves, called the brachial plexus. The brachial plexus passes between the anterior and middle scalene muscles, then underneath the clavicle and continues underneath the pectoralis minor before diverging into different peripheral nerves down the arm.

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The 4 Types of Thoracic Outlet Syndrome (TOS):

The nerves of the brachial plexus can be compressed in several locations near the thoracic outlet. Mainly these four areas:

  1. An anatomical abnormality called a cervical rib: Which is an extra rib that extends from the transverse process of the C7 vertebra (neck vertebra). Approximately half of the people with the presence of a cervical rib; have symptoms of TOS. Due to the brachial plexus crossing over the cervical rib; this causes numbness and/or tingling down the arms and into the fingers. The person may be irritated from the chronic condition. Treatment includes surgical removal of the cervical rib.

cervical rib revolution health centre thoracic outlet syndrome numbness in hands and arms

2.  Anterior Scalene Syndrome: Caused by the brachial plexus and subclavian artery being entrapped between the anterior and middle scalene muscles. The causes of this type of TOS is tight neck muscles (anterior & middle scalenes) that usually contain trigger points (‘knots’). The person with Anterior Scalene Syndrome will experience numbness or tingling down the outside of their forearm, thumb and index finger. Pain will radiate down shoulder and arm (over biceps and triceps), the upper chest, as well as in-between the shoulder blades. It is common for sufferers to wake during the night due to numb arms, or pain in their shoulders. See first image.

3. Costoclavicular Syndrome: Involves compression of the brachial plexus between the first rib and the clavicle. A tight subclavian muscle will lead to compression of the brachial plexus and subclavian artery and vein. This situation is made worse by rounded shoulders and head forward posture. Can also be caused from repetitive shoulder use like handbags, heavy school bags, or carrying objects on the shoulder. The repetitive strain will cause the subclavian muscle to become tight and contain trigger points. Symptoms of Costoclavicular Syndrome are numbness down arms, pain in chest area, poor circulation in arms and hands (compressed subclavian artery), swelling in the affected arm and hand (compressed subclavian vein). It is common for sufferers to wake during the night due to numb arms, or pain in their shoulders. See image below.

sub clavius revolution health centre thoracic outlet syndrome numbness down arms and hands colac camperdown

4. Pectoralis Minor Syndrome: The pectoralis minor muscle can compress the brachial plexus as it passes beneath this muscle and pressing the brachial plexus against the rib cage. This can occur due to specific activities that require the arm to be elevated over the head for a prolonged time; such as when painting a ceiling or playing and instrument like a violin or flute. It can also be caused from staying in one position for a prolonged period, ie. Sleeping with your arm above your head, or leaning your elbow on a table. Symptoms of Pectoralis Minor Syndrome are numbness down arms, pain and tightness in chest and shoulder area. Signs that the Pectoralis Muscle is tight; is the scapula ‘sticking out’ or ‘winging’. It is common for sufferers to wake during the night due to numb arms, or pain in their shoulders. See above image.

Note: TOS can also be caused by whiplash (due to inflammation and subsequent scarring) and pregnancy (due to increased fluid retention and postural changes).


Thoracic Outlet Syndrome can be successfully treated by using remedial massage. A skilled practitioner can work to relax the muscles involved, and ‘decompress’ the trapped nerves and blood vessels. As we mentioned above, symptoms of Cervical Rib TOS can be eliminated by removing the extra rib. However, this can cause its own problems. We recommend trying massage to release the surrounding tissue to see if that provides any relief.