Absence of the subclavius muscle with contralateral subclavius posticus muscle: first imaging report.

We present a case of a 56-year-old man with pain in in his right anterior shoulder, arm, and hand. MRI studies demonstrated absence of the subclavius muscle with contralateral subclavius posticus muscle. To our knowledge, imaging of the total absence of subclavius muscle has not been previously described. Understanding and recognition of subclavius posticus muscle are important for its potential role in thoracic outlet syndrome.