General Structure and Position
Anatomo-topographically, the palatine bone (Os palatinum) is a paired structure. It is located in the deep regions of the facial skeleton and features a complex spatial organization. The bone establishes close topographical relationships with the maxilla anteriorly and the sphenoid bone posteriorly, while also directly participating in the formation of the bony walls of the nasal cavity.
Fundamentally, the bone consists of two main elements positioned at an angle to each other:
- Perpendicular plate (Lamina perpendicularis);
- Horizontal plate (Lamina horizontalis).
Perpendicular Plate
The perpendicular plate (Lamina perpendicularis) is oriented vertically. On an intact skull, this structure is particularly convenient to demonstrate and study on the lateral wall of the nasal cavity when viewed from the choanae.
The plate has two prominent surfaces, each bearing important anatomical landmarks:
- Lateral surface (maxillary surface) — Facies maxillaris. It faces outward toward the pterygopalatine fossa. A characteristic feature of this surface is the vertically running greater palatine groove (Sulcus palatinus major). When articulated with the corresponding groove on the maxilla, it closes to form the complete greater palatine canal.
- Medial surface (nasal surface) — Facies nasalis. This side is directed straight into the nasal cavity. It features two prominent horizontal bone ridges: the ethmoidal crest (Crista ethmoidalis) and, located inferiorly, the conchal crest (Crista conchalis).
Processes of the Perpendicular Plate
Several important processes project from the perpendicular plate, ensuring articulation with neighboring bones.
In the upper part of the plate, two distinct processes emerge:
- Orbital process (Processus orbitalis) — directed anteriorly and superiorly, participating in the formation of the medial wall of the orbit.
- Sphenoidal process (Processus sphenoidalis) — directed posteriorly, closely apposed to the body of the sphenoid bone.
Between these two superior processes, a deep sphenopalatine notch (Incisura sphenopalatina) is formed. On the intact skull, it serves as a crucial passage for blood vessels and nerve trunks entering the nasal cavity.
Posteroinferiorly, the perpendicular plate continues massively into the pyramidal process (Processus pyramidalis). It wedges between the plates of the pterygoid process of the sphenoid bone, thereby completing the pterygoid fossa (Fossa pterygoidea). Directly in the region of the pyramidal process, the lesser palatine foramina (Foramina palatina minora) can be found, which lead into the lesser palatine canals (Canales palatini minores). These small canals internally communicate with the main greater palatine canal.
Horizontal Plate
The horizontal plate (Lamina horizontalis) lies in the horizontal plane and functions to complete the posterior part of the bony hard palate.
It also features two surfaces with distinct reliefs:
- Superior (nasal) surface — Facies nasalis. Faces toward the floor of the nasal cavity. It bears the nasal crest (Crista nasalis), which runs in the sagittal direction and terminates at its posterior end in a sharp projection — the posterior nasal spine (Spina nasalis posterior).
- Inferior (palatine) surface — Facies palatina. Faces the oral cavity. Along its midline runs the distinct palatine crest (Crista palatina).