Background: It is usual to come across deviations from normal in human cranial bones. Incidence is little higher in bones of the vault and face which are formed by membranous ossification. Presence of bipartite zygomatic bone has been described since long. The division of zygomatic bone has been described to occur commonly in Mongolian race and hence such extra portion is known as os japonicum.
Objective: To study the incidence of bipartite zygomatic bones in Gujarat state.
Materials and Methods: This study was carried out on 486 zygomatic bones of 243 dry normal, adult, human skulls obtained from collection of bones in anatomy departments of various medical colleges of Gujarat. The bones studied were free of any pathological condition. The skulls were cleaned, dried, and observed in good day light and with the help of magnifying lens.
Result: The observations for presence of suture/sutures, their extent, directions, and variations in 486 zygomatic bones revealed that 21 zygomatic bones had bipartitism. This study showed 4.32% incidence of os japonicum among observed zygomatic bones in Gujarat state.
Conclusion: Zygomatic bone gets fractured commonly in facial injuries. Bipartite zygomatic bone is not uncommon and can be confused with the fracture of the bone.
Zygomatic, bipartitism, os japonicum, fracture