The perpendicular plate of the ethmoid bone is quadrangular in shape, descends in the midline from the cribriform plate, and forms the upper part of the median nasal septum (Fig. 8.233). It articulates: posteriorly with the sphenoidal crest on the body of the sphenoid bone, anteriorly with the nasal spine on the frontal bone and with the site of articulation at the midline between the two nasal bones, and inferiorly and anteriorly with the septal cartilage and posteriorly with the vomer.