Thread by @BadgleyLaurence

Botox yes! In TOS 1 Superior trapezius usually spastic/hyperdynamic; inducing same-side Pectoralis minor muscle to be spastic/hyperdynamic. These muscles control directional shift of distal clavicle; which, as drawn inferior, closes Thoracic Outlet (1 cm vs. clavicle & 1st rib).

The physical exam should note shoulder asymmetry; one shoulder lower with head usually tilted toward lower shoulder. The tilted 10# head often induces spasm & hypertrophy of Superior trapezius associated with opposite & higher shoulder.

Superior trapezius hyperdynamic function then induces spasm/hypertrophy within same-side opposing (shoulder lift & draw-down are complementary functions) Pectoralis minor (PM) muscle. It is PM hyperdynamic function that draws distal clavicle excessively inferior in TOS disorder.

The clavicle is about 18 cm long & 1 cm of excess inferior shift can close the Thoracic Outlet (TO) by ~30%; impinging brachial neurovascular bundle contents of the TO.

That part of the brachial neural plexus that gives rise to the ulnar nerve is the first part of the brachial neural plexus impinged as Thoracic Outlet closes; anatomical explanation why ulnar paresthesias are most common dysesthesia aroused by arm-shoulder abduction with TOS.

After surgeons failed to cure TOS with flayed/excision of Scalenes (~1980’s theory of TOS etiology), they discovered that Pectoralis muscle release (off corocoid process) & tie-down of first rib to 2nd (axilla surgical entrance) was therapeutic; opened up the Thoracic Outlet.

Yet this surgical approach seems somewhat butchery. Better to reduce “crossed muscle” asymmetry of Superior trapezium (strengthen weaker Superior trapezius with isometric & shrug exercises) & induce muscle relaxation of spastic shoulder muscles with massage, Botox & biofeedback.

The theories and practices referenced in this thread are my own novel insights and inventions; gained from years toiling in the clinical trenches. I have created several other threadreaders about TOS.