Isolated lateral pectoral nerve injury: trauma from a seat belt.

A 35-year-old man sustained an isolated injury to the lateral pectoral (anterior thoracic) nerve as the result of a seat belt injury. This resulted in atrophy of the clavicular head of the pectoralis major. Electromyography confirmed localized abnormal findings in this muscle and an isolated lesion of the lateral pectoral nerve, the first reported case of such a lesion.