Basal lamella
The basal lamella, also known as basal lamella of the middle turbinate, is an osseous lamella that separates the anterior from the posterior ethmoid sinuses .
Terminology
Internal anterior to posterior partitions of the ethmoid sinuses are called basal lamellae. According to a concept proposed by Killian, four or five (if supreme turbinate is included) basal lamellae make up the ethmoid sinuses .
The third basal lamella is the only complete basal lamellae, i.e. the only one that reaches the lamina papyracea from the lateral nasal wall . As such, the singular term basal lamella refers specifically to the third basal lamella.
The fourth basal lamella separates posterior ethmoid cells into posterior and postreme cells.