Palatine bone

Surfaces

The nasal surface of the perpendicular plate faces the nasal cavity, forming a part of its lateral wall. The inferior part of this surface is marked by a concavity that contributes to the inferior nasal meatus. Superior to this is the conchal crest, via which it articulates with the inferior nasal concha. Above this crest there is a shallow concavity that comprises a part of the middle nasal meatus. Superior to this concavity is the ethmoidal crest, onto which the middle nasal concha attaches.

The maxillary surface of the perpendicular place articulates with the nasal surface of the maxilla. It is mostly rough and irregular, except in its posterosuperior and anterior portions. The posterosuperior smooth area forms the medial wall of the pterygopalatine fossa, while the anterior smooth area forms the posterior portion of the medial wall of the maxillary sinus. The maxillary surface is also marked by an oblique groove called the greater palatine groove. It transmits the structures which pass through the greater palatine foramen. The adjacent surface of the maxilla closes this groove, converting it into the greater palatine canal, which transmits the greater palatine nerve, artery and vein.

Borders

The borders of the perpendicular plate serve for the articulations with the neighboring bones. 

• The anterior border shows a laminar projection at the level of the conchal crest that articulates with the inferior nasal concha and forms a part of the medial wall of the maxillary sinus. 
• The posterior border is serrated and it articulates with the medial pterygoid plate of the sphenoid bone. The sphenoidal process continues from the superior part of the posterior border, whilst the pyramidal process continues from its inferior part.
• The superior border articulates with the body of the sphenoid bone. It is marked by the sphenopalatine notch, which is closed superiorly by the sphenoid body and converted into the sphenopalatine foramen. This foramen is a connection between the pterygopalatine fossa and superior nasal meatus, transmitting the posterior superior nasal nerves and sphenopalatine vessels between them. The anterior part of the superior border projects into the orbital process of the palatine bone.
• The inferior border of the perpendicular plate is continuous with the lateral border of the horizontal plate.

For more details about the palatine bone, take a look at the videos, illustrations and quizzes in the following study unit:

Pyramidal process

The pyramidal process of the palatine bone arises from the junction between the horizontal and perpendicular plates. It is oriented posterolaterally, passing between the medial and lateral pterygoid plates of the sphenoid bone. The posterior surface of this process articulates with the pterygoid plates, forming the inferior part of the pterygoid fossa. The lateral surface provides the attaching site for the deep head of the medial pterygoid muscle, while the inferior surface features the lesser palatine foramina for the passage of the lesser palatine nerves and vessels.

Orbital process

The orbital process originates from the anterior part of the orbital margin of the perpendicular plate. It is directed superiorly and slightly anteriorly, coursing towards the floor of the orbit. This process shows a narrow neck, three articular, and two non-articular surfaces.

• The anterior (maxillary) surface is directed anteriorly and laterally and it articulates with the maxilla. 
• The posterior (sphenoidal) surface faces superiorly and posteromedially andt is marked by an opening of an air sinus that is contained within this process, via which this sinus communicates with the sphenoidal sinus. 
• The medial (ethmoidal) surface courses anteriorly and medially. It articulates with the labyrinth of the ethmoid bone. In some individuals, this surface is the one that contains an opening of the air sinus instead of the posterior surface. In this case, the bone communicates with the posterior ethmoidal air cells rather than with the sphenoidal sinus. 

The two non-articular surfaces of the orbital process are the superior (orbital) and lateral. The superior (orbital) surface forms a part of the floor of the bony orbit, while the lateral surface forms a part of the pterygopalatine fossa. These two surfaces are separated by a notch that forms the medial part of the inferior border of the inferior orbital fissure.

Sphenoidal process

The sphenoidal process courses superomedially from the superior part of the posterior border of the perpendicular plate.

• Its superior surface articulates with the sphenoidal concha and the root of the medial pterygoid plate. This surface is also marked by a groove that forms a part of the palatovaginal canal. 
• The inferomedial surface is concave and it forms a part of the floor and lateral wall of the nasal cavity. 
• The lateral surface contributes to the part of the medial wall of the pterygopalatine fossa.

The sphenoidal process has three borders. The posterior border articulates with the medial pterygoid plate, while the medial border articulates with the ala of the vomer. The anterior border forms the posterior margin of the sphenopalatine notch.