The Palatine Bone
The palatine bone consists of a horizontal and perpendicular plate and the pyramidal process. The horizontal plate forms the posterior portion of the hard palate of the oral cavity and is directly inferior to the nasal cavity. The posterior nasal spine sits at the back of the horizontal plate where the two opposing palatine bones articulate. This medial area contains the greater palatine foramen which houses the greater palatine nerve and its corresponding vessels.
The perpendicular plate contributes to the lateral wall of the nasal cavity where it borders the pterygoid process of sphenoid bone. The orbital process arises anterosuperiorly forming part of the orbital floor and pterygopalatine fossa. Two further landmarks include the palatine canal (running between the lateral wall of the palatine bone and the maxilla) and the sphenopalatine notch on the superior border which articulates with the sphenoid bone.
The pyramidal process extends posteroinferiorly at the junction between the perpendicular and horizontal plate. It comprises the lesser palatine canals where the corresponding nerves and vessels pass through.
The palatine bone is bordered by the maxilla anteriorly (transverse palatine suture). Posteriorly it serves as an attachment to the velum and palatine aponeurosis and the posterior border of the perpendicular plate articulates with the medial pterygoid plate of the sphenoid bone. Superiorly the orbital process builds the posterior part of the orbital floor. Both palatine bones border each other at their medial surfaces (posterior median palatine suture).
All the parts of the palatine bone mature through intramembranous ossification. During embryological development it comprises four ossification centers (located in the pyramidal, orbital and sphenoidal processes and horizontal plate). In newborns both the perpendicular and horizontal plates are equally long, however in the course of childhood the horizontal plate become larger.
The greater and lesser palatine nerves, found in the horizontal plate and the pyramidal process of the palatine bone respectively, are quite sensitive. This is why they need to be anesthetized before the extraction of the upper premolars and molars. For this procedure the needle is inserted on the medial side of the (adult) second molar, 1 cm from the gingival margin. Hereby the dentist ought to be careful not to use too much force and penetrate the greater palatine foramen.