Anomalous muscles associated with compression neuropathies.

: Muscle anomalies are common in the upper extremity but are usually only discovered at cadaveric dissection. Anomalous muscles associated with compression neuropathies are reviewed. The clinical significance of anomalies is recognition of the associated compression patterns that occur. Surgical excision is employed as part of standard decompressive procedures. Four illustrative cases of anomalies discovered at surgical exploration are presented.