Thoracic outlet syndrome occurs when neurovascular structures — the brachial plexus nerves, and sometimes the subclavian artery or vein — are compressed as they pass through the space between the collarbone and first rib on their way into the arm. The result is a constellation of symptoms that mimics several other, more commonly diagnosed conditions: arm and hand numbness and tingling, shoulder and neck pain, arm fatigue with overhead activities, and in vascular cases, color or temperature changes in the hand.
Because the symptom profile overlaps so much with carpal tunnel syndrome, cervical disc disease, and rotator cuff pathology, TOS is frequently misdiagnosed or missed entirely for months to years. The population most commonly affected includes overhead athletes — swimmers, baseball players, tennis players — desk workers with forward head posture and rounded shoulders, and people who perform repetitive overhead occupational tasks.
- Symptoms clearly triggered by sustained overhead position or forward-head posture
- Arm and hand tingling that resolves promptly when position is changed
- Both sides equally affected, correlating with workstation setup or activity patterns
- No weakness, no color change in the hand, no cervical spine symptoms
- Unilateral symptoms that are progressive and not clearly position-dependent
- Color changes in the hand — pallor, bluish discoloration, or temperature asymmetry between hands
- Arm swelling or a sensation of heaviness that is new and progressive
- Weakness developing in the hand or grip, particularly on one side
- Symptoms present for months without improvement despite postural correction
The pectoralis minor connection
The pectoralis minor muscle, which attaches from the front of the shoulder to the ribs, plays a significant role in neurogenic TOS: when shortened and tight, it compresses the brachial plexus against the chest wall in a way that produces hand and arm symptoms that are position-dependent and often misattributed to a wrist or elbow source.
"Sustained stretching of the pec minor, combined with postural correction and scapular strengthening, resolves a significant percentage of neurogenic TOS cases without surgery. The work is worth doing early."
A useful self-assessment: the pectoralis minor stretch. Stand in a doorway with your arm at 90 degrees at the shoulder, elbow bent, forearm resting against the door frame. Lean gently forward until you feel a stretch across the front of the chest and shoulder. If this position reproduces your arm or hand symptoms, it is a meaningful signal that the pec minor is involved in compressing the neurovascular bundle.
Watch the thoracic outlet stretch demo on Instagram.
@formandfunctionmd →- Sanders RJ, Hammond SL, Rao NM. Diagnosis of thoracic outlet syndrome. Journal of Vascular Surgery. 2007;46(3):601–604. doi:10.1016/j.jvs.2007.04.050
- Povlsen B, Hansson T, Povlsen SD. Treatment for thoracic outlet syndrome. Cochrane Database of Systematic Reviews. 2014;(11):CD007218. doi:10.1002/14651858.CD007218.pub3
- Hooper TL, Denton J, McGalliard MK, Brismée JM, Sizer PS. Thoracic outlet syndrome: a controversial clinical condition. Journal of Manual & Manipulative Therapy. 2010;18(2):74–83. doi:10.1179/106698110X12640740712734