"154"^^ . . "Ethmoid+Sinus"@en . . "12225634" . "The ethmoidal sinuses or ethmoidal air cells of the ethmoid bone are one of the four paired paranasal sinuses. They are a variable in both size and number of small cavities in the lateral mass of each of the ethmoid bones and cannot be palpated during an extraoral examination. They are divided into the anterior, middle and posterior groups (see below)."@en . "36"^^ . "A04.531.621.267" . "c_19" . "Ethmoidal sinus"@en .