Dorsoventral radiograph of dromedary skull. 1. Incisive bone; 2. upper canine teeth; 3. third upper premolar; 4. first upper molar; 5. second upper molar; 6. third upper molar; 7. maxillary sinus; 8. zygomatic process of frontal bone; 9. lacrimal sinus; 10. diverticula of frontal sinus; 11. vomer bone; 12. basisphenoid bone; 13. zygomatic arch; 14. frontal bone; 15. occipital bone