What is Thoracic Outlet Syndrome?

The thoracic outlet is the space between the anterior scalene muscles in the side of the neck and the rib cage. Nerves and blood vessels (neurovascular bundle), which originate in the cervical spine run down the neck through the thoracic outlet, under the clavicle (collarbone), through the axilla (armpit) and extend further into the arm. These nerves and blood vessels allow for normal sensory and vascular supply.
Thoracic outlet syndrome (TOS) is a compression or irritation to the nerves and blood vessels passing through the thoracic outlet. Once these structures are compressed there will be sensation differences to the arm or forearm such as: pins and needles, pain, paraesthesia, loss of muscle strength and coldness.

There are several types of thoracic outlet syndrome. First, the neurovascular bundle can be compressed in or by the anterior scalene muscles at the side of the neck. Second, the presence of a cervical rib, which is an extra rib arising from the seventh cervical vertebra, can cause compression to the neurovascular bundle. Third, the thoracic outlet space can be reduced thereby restricting the neurovascular bundle. Lastly, the pectoralis minor muscle, which is located in the upper chest, can spasm, depress the scapula and cause a compression to the neurovascular bundle.

Anterior Scalene Syndrome:
Anterior Scalene Syndrome is a Thoracic Outlet Syndrome where the neurovascular bundle is compressed by the scaleni anticus and medius muscles (anterior scalene muscles). These muscles can spasm due to some trauma or may become hypertonic due to unusual posture.

Anterior Scalene Syndrome can often be caused by congenital anomaly, trauma, traumatic myositis, and hypertrophy of scalenus anterior muscle. Other common causes may include; physical trauma from being in a car accident, anatomical defects, pregnancy and repetitive injuries.

This condition causes pain in the neck and shoulders, as well as numbness in the fingers. Other symptoms may include; extremity paraesthesia, pain and weakness as well as neck pain due to brachial plexus compression.

Cervical Rib Syndrome:
Cervical Rib Syndrome is a Thoracic Outlet Syndrome in which a rudimentary cervical rib located at the C7 vertebrae compresses the neurovascular bundle. The presence of this rudimentary or extra cervical rib is very small, about 1% of the population will have a cervical rib.

Cervical Rib Syndrome is a congenital (existing from birth) condition and is caused by an extra growth of bone (or rib) that is present in the lower cervical spine (neck).

This condition can often be present without causing any symptoms, however, there may be a few symptoms present. These may include; pain in your neck and shoulder, which spreads into your arm, temporary loss of feeling, weakness or tingling, and a temporary inability to carry out fine hand movements.

Costoclavicular Syndrome:
Costoclavicular Syndrome is a Thoracic Outlet Syndrome where there is narrowing of the space between the clavicle and first rib. This results in compression of the brachial plexus (nerve bundle) and subclavian artery.

Common causes of Costoclavicular Syndrome may include; having a postural condition of rounding and slumping shoulders (this narrows the costoclavicular passage by pushing the scapula forwards.), those who have laboured breathing tend to cause Costoclavicular Syndrome because it causes the first rib to elevate toward/against the clavicle. This condition is very common in obese, middle aged or elderly women.

The main symptoms for Costoclavicular Syndrome may include; pain or aching, which is sometimes accompanied by stiffness in the neck and shoulders, paraesthesia, and fatigue of the upper limbs.

Pectoralis Minor Syndrome:
Pectoralis Minor Syndrome or Hyperabduction Syndrome is a Thoracic Outlet Syndrome where the pectoralis minor muscle spasms, compressing the brachial plexus (nerve bundle). Occupations with a high rate of repetitive movements will produce sustained muscle tension and result in symptoms.

Acute traumas, repetitive daily activities, exercises, and sports are all common causes of Pectoralis Minor Syndrome. Through repetitive overuse, trigger points can become active as the muscle tightens up. Another cause of this condition is poor posture.

The symptoms of Pectoralis Minor Syndrome is similar to that of Costoclavicular Syndrome, with shoulder, neck, chest, and arm pain, and paraesthesia and weakness in the arm and hand.


Here at Precision Health we offer services such as chiropractic care and massage therapy which can aid in your recovery from Thoracic Outlet Syndromes (anterior Scalene Syndrome).

Call (02) 9639 7337 or visit our website to book an appointment now!

Jones, M.R., Prabhakar, A., Viswanath, O. et al. Thoracic Outlet Syndrome: A Comprehensive Review of Pathophysiology, Diagnosis, and Treatment. Pain Ther 8, 5–18 (2019). https://doi.org/10.1007/s40122-019-0124-2

Book Now With Precision Health today and take the first step towards better health!

Book Now

Take care of your health with precision!

Precision Health Spine & Sports clinic treats a diverse range of neuromuscular and skeletal biomechanical disorders. Whether you are having trouble with your knees, you have a pain in the neck, or if you are just feeling stiff and sore, we can help you with our suite of treatment options that can be tailored especially for you. Take a look at the wide range of disorders we can help you with. Whether you need chiropractic treatment, remedial massage, physiotherapy, podiatry or a combination of disciplines, we have the expertise to decrease your pain and discomfort and increase your mobility and quality of life.