Vomero-premaxillary joint: A marker of evolution of the species.

OBJECTIVE: According to evolutionary developmental (evo-devo) theory, the vomers are bones derived from the secondary palate. Growth of the palatine processes of the maxillae, including the precursors of vomer bones, results in midline fusion posteriorly to the primary palate, which forces the ascension of the vomer bones towards the primary nasal septum, formed by septal cartilage and the perpendicular plate of the ethmoid. According to this hypothesis, the anterior border of the vomer articulates with the posterior surface of the premaxilla in the incisive canal (IC).

MATERIAL AND METHOD: The objective of this retrospective study was to measure the degree of impaction of the anteroinferior angle of the vomer in the IC on CT scans showing a non-deformed nasal septum. Thirty-two out of a series of 506 nasal sinus CT scans were used to obtain measurements on coronal sections of non-deformed septa through the IC.

RESULTS: Thirty-one of the 32 vomers were impacted in the IC. In the case of a Y-shaped vomer (n=26), 43% of the length of the vomer was impacted in 41% of the length of the IC. In the case of I-shaped vomers (n=6), 34% of the length of the vomer was impacted in 41% of the length of the IC. The only vomer that did not impact into the IC was Y-shaped.

CONCLUSION: Impaction of the vomer in the IC posteriorly to the premaxilla can be explained by the evo-devo concept of the formation of the nasal cavities. In contrast, the classical embryological description of the formation of the nasal septum cannot provide an explanation for impaction of the vomer.