The hard palate, as seen on the basal aspect of the skull, has its anterior two-thirds to three-quarters made by the palatine plates of the maxillae, with the horizontal plates of the palate bones forming the posterior third or fourth. It is bounded by the alveolar process, which is highest at the sides. The region is concave as a whole in all directions. The anterior palatine foramen is just behind the incisor region ; this is covered by the incisive papilla in the recent state. Behind this the palate is rough and has the mucous membrane firmly adherent to it-the membrane becomes thicker further back and leaves the bone smoother, although there are more abundant glands in this situation.
The (large) posterior palatine foramen is seen immediately internal to the alveolus of the last molar tooth, and the suture line between maxilla and palate turns sharply back along the alveolus to run into the foramen, indicating that the canal is made by the articulation of the two bones. The main posterior palatine vessels and nerve emerge here and turn forward toward the anterior palatine foramen, through which the artery turns up on to the septum. The groove containing the structures is frequently double, in which case the artery occupies the groove nearer the alveolus. Behind the main opening another or perhaps two are visible ; these are for smaller nerves and vessels belonging to the same group but turning back into the soft palate. The aponeurosis of the Tensor palati reaches a ridge which runs transversely between the foramina. In this region the lower surface of the horizontal plate of the palate can be seen to pass directly into the lower surface of the tuberosity, behind the foramina. The posterior edge is thin and concave, being prolonged centrally into a posterior nasal spine.
The region of the palatine suture is occasionally raised in the whole or part of its length into a prominent ridge, known as the torus palatinus. A variety of palate is rarely seen in which the maxillae are produced backwards between the palate bones centrally. The commonest abnormality of the palate is " cleft palate," in which the two palate-folds have failed to unite with each other, and if the cleft is complete, and extends to the face, the fold at fault has also failed in union with the fronto-nasal process : such failure may be on one or both sides. Fig. 186 shows how the deformity can occur, and it is evident that if the folds fail to meet the bones cannot join subsequently.
As already mentioned, the secondary down-growths of the hinder walls of the alveoli of the incisor region, toward the anterior palatine foramen, make the surface of this part of the bony palate, and one or other of these processes may fail to unite with its neighbour : this leads to the presence of a fissure extending out from the foramen. Such a fissure may appear between the incisors, or to the outer side of the lateral incisor, or in rare cases even to the outer side of the canine. The fissure was for many years considered to mark the limit of the " premaxilla," but its irregularity of position, and the fact that it has even been seen doubled on one or both sides, was sufficient argument against this view, and now it is known to be of quite secondary origin, as described. It is of historical interest to note, also, that the presence of these fissures at one time led to the adoption by many of the suggestion that the alveolar portion of the upper jaw resulted from the fusion of three distinct parts, the endognathion, placed on the inner nasal process and carrying the central incisor, the mesognathion on the lateral process bearing the lateral incisor, and the txo-enathion further out. There is, of course, no justification in development for this view, which was introduced really to explain not only the occurrence of double fissures, but also the presence of teeth bearing unusual relation to clefts in the palate and alveolus. These extra teeth, however, are more rationally explained on the assumption of breaking up of the dental epithelial area over the situation of the cleft.
The palate is considerably narrower in female skulls than in those of the other sex.