PALATE BONES. 



167 



Fig. 119. Left Palate Bone. 

 View (enlarged). 



Posterior 



extent, for articulation with the inner surface of the superior maxillary bone, 

 its upper and back part being smooth where it enters into the formation of the 

 spheno- maxillary fossa; it is also smooth in front, where it covers the orifice 

 of the antrum. Towards the back part of this surface is a deep groove, con- 

 verted into a canal, the posterior palatine, by its articulation with the superior 

 maxillary bone. It transmits the posterior, or descending palatine vessels, and 

 a large nerve. 



The anterior border is thin, irregular, and presents opposite the inferior 

 turbinated crest a pointed projecting lamina, the maxillary process, which is 

 directed forwards, and closes in the lower 

 and back part of the opening of the an- 

 trum, being received into a fissure that 

 exists at the inferior part of this aper- 

 ture. The posterior border (Fig. 119) 

 presents a deep groove, the edges of 

 which are serrated for articulation with 

 the pterygoid process of the sphenoid. 

 At the lower part of this border is seen 

 a pyramidal process of bone, the ptery- 

 goid process or tuberosity of the palate, 

 which is received into the angular in- 

 terval between the two pterygoid plates 

 of the sphenoid at their inferior ex- 

 tremity. This process presents, at its 

 back part, three grooves, a median, and 

 two lateral ones. The former is smooth, 

 and forms part of the pterygoid fossa, 

 affording attachment to the Internal 

 Pterygoid muscle; whilst the lateral 

 grooves are rough and uneven, for ar- 

 ticulation with the anterior border of 

 each pterygoid plate. A few fibres of 



the External Pterygoid muscle also arise from the tuberosity of the palate 

 bone. The base of this process, continuous with the horizontal portion of the 

 bone, presents the apertures of the accessory descending palatine canals ; whilst 

 its outer surface is rough for articulation with the inner surface of the body of 

 the superior maxillary bone. 



The superior border of the vertical plate presents two well-marked processes 

 separated by an intervening notch or foramen. The anterior, or larger, is called 

 the orbital process ; the posterior, the sphenoidal. 



The Orbital Process, directed upwards and outwards, is placed on a higher 

 level than the sphenoidal. It presents five surfaces, which inclose a hollow 

 cellular cavity, and is connected to the perpendicular plate by a narrow con- 

 stricted neck. Of these five surfaces three are articular, two non-articular, or 

 free surfaces. The three articular are the anterior or maxillary surface, which 

 is directed forwards, outwards, and downwards, is of an oblong form, and rough 

 for articulation with the superior maxillary bone. The posterior or sphenoidal 

 surface is directed backwards, upwards, and inwards. It ordinarily presents a 

 small open cell, which communicates with the sphenoidal sinus, and the mar- 

 gins of which are serrated for articulation with the vertical part of the sphe- 

 noidal turbinated bone. The internal or ethmoidal surface is directed inwards,, 

 upwards, and forwards, and articulates with the lateral mass of the ethmoid, 

 bone. In some cases, the cellular cavity above-mentioned opens on this sur- 

 face of the bone ; it then communicates with the posterior ethmoid cells. More 

 rarely it opens on both surfaces, and then communicates both with the pos- 

 terior ethmoidal cells, and the sphenoidal sinus. The non-articular or free sur- 

 faces are the superior or orbital, directed upwards and outwards, of triangular- 



