Abstract
Divided frontal sinus is almost a constant finding in the dog, while this is quite rart (3-6%) in human. In the dog, the four frontal cells are formed successively in the order : the third, the second and the first sini, the sini being numbered from the ventral to the dorsal side. In human, , on the other hand, they are formed in the order : the first, the second and the third sini.
In the dog, the concha f rontalis enters into the entrance of the divided frontal sinus, turning and winding with each other, namely, it is oriented outward in the third sinus and inward in the second sinus.
