Clinical and radiographic variations in hemifacial microsomia.

Variations expressed clinically and radiographically in hemifacial microsomia preclude classifying all the abnormalities as coming from the first and second branchial arches. Anatomic structures arising from the branchial arches are directly involved but the final expression results from the combined impact of the primary anatomic defect and the secondary effects on contiguous structures. The deformities resulting from the latter are probably due to abnormal neuromuscular function.