Joint between sphenoid & vomer is

Schindylesis is that form of aiculation in which a thin plate of bone is received into a cleft or fissure formed by the separation of two lamina in another bone, as in the aiculation of the rostrum of the sphenoid and perpendicular plate of the ethmoid with the vomer, or in the reception of the latter in the fissure between the maxilla and between the palatine bones. Ref: Henry Gray. Anatomy of the Human Body.