Ectoturbinate

The ectoturbinates or ectoturbinate volutes are bony structures that make up part of the ethmoid labyrinth, forming from the dorsal and lateral walls of the ethmoid bone.

Unlike endoturbinates, which are longer and deeper, ectoturbinates, which are superficial and short, are generally arranged in a single row, with equines differing in that they have a double row. Each ectoturbinate has a basal lamella, which attaches to the cribriform plate or the walls of the ethmoid bone, and a spiral-shaped lamella that projects into the nasal cavity.

Their number varies considerably between species, with dogs, ruminants, pigs, and equines having 6, 13 to 18, 18 to 20, and 21 to 31 ectoturbinates, respectively. The ectoturbinates participate in the formation of the nasal meatuses and, in dogs (though not exclusively in them), the spaces between them allow communication between the paranasal sinuses and the nasal cavity.