Pectoralis minor syndrome

Pectoralis minor syndrome (PMS) is a condition related to thoracic outlet syndrome (TOS) that results from the pectoralis minor muscle being too tight. PMS results from the brachial plexus being compressed under the pectoralis minor while TOS involves compression of the bundle above the clavicle.

Source: Wikipedia — Pectoralis minor syndrome (CC BY-SA 4.0)