Immediately above this is a well-marked horizontal ridge, the conchal crest, for articulation with the inferior nasal concha; still higher is a second broad, shallow depression, which forms part of the middle meatus, and is limited above by a horizontal crest less prominent than the inferior, the ethmoidal crest, for articulation with the middle nasal concha.
2.
Its " medial surface " forms part of the lateral wall of the nasal cavity; at its upper part is a rough, uneven area, which articulates with the ethmoid, closing in the anterior ethmoidal cells; below this is an oblique ridge, the ethmoidal crest, the posterior end of which articulates with the middle nasal concha, while the anterior part is termed the agger nasi; the crest forms the upper limit of the atrium of the middle meatus.