lateral ethmoid Tomasz Adamusiak Large, paired cartilage bones separating the olfactory region from the orbit. Arises from both perichondral and endochondral ossifications (Harrington 1955). Bordered by the mesethmoid anteriorly and overlain by the frontal dorsally, each lateral ethmoid extends medially to meet its fellow posteriorly along the midline. Develops from the laminae orbitonasales. lateral ethmoids ZFA:0000226 zebrafish component