50 BONES OF THE HEAD. 



giving attachment to the soft palate or vehim : anteriorly it articu- 

 lates with the palate plate of the superior maxillary bone, and inter- 

 nally by a thick serrated border with its fellow of the opposite side, 

 forming with it a ridge or crest for articulation with the vomer, 

 continuous with that of the superior maxillaries; externally, at its 

 junction with the vertical plate, it is grooved by the extremity of the 

 posterior palatine canal. Its superior surface is smooth, and forms the 

 back part of the floor of the nasal cavity ; its inferior surface is rough, 

 and is marked near its posterior border by a transverse ridge which 

 gives attachment to the tendinous fibres of the tensor palati muscle. 



The vertical jilatc is very thin. Its internal or nasal surface is divided 

 into two parts, corresponding to the middle and inferior meatus of the 

 ' nose, Ijy a nearly horizontal ridge which articulates with the inferior 

 turbinated bone. The external surface is smooth, and at its upper part 

 forms the internal Avail of the spheno-maxillary fossa, while the lower 

 part is hollowed into a deep groove, completing with the superior maxil- 

 lary the posterior palatine canal, which transmits the large descending 

 palatine nerve and vessels. In front of this canal the external surface is 

 in contact with the internal surface of the maxillary bone and the inner 

 side of the antrum ; behind the canal it articulates inferiorly with the 

 hinder border of the maxilla, superiorly with the inner surface of the 

 pterygoid process. 



The pyramidal process or tulerosity fits into the cleft between the 

 pterygoid plates. It presents posteriorly a triangular surface which is 

 smooth and grooved, and completes the pterygoid fossa ; on its sides it 

 is rough for articulation with the borders of the 'pterygoid plates. 

 Inferiorly, close to its connection with the horizontal plate, are two 

 small foramina, the posterior and external small palatine foramina, the 

 extremities of two minute canals which transmit the smaller palatine 

 nerves ; the external one is the smaller and is inconstant. 



The orbital process surmounts the anterior margin of the vertical plate. 

 It is somewhat pyramidal in shape, and has five surfaces, two of which, 

 the superior and external, are free, and the rest articulated. The 

 superior surface forms the posterior angle of the floor of the orbit ; the 

 external looks into the spheno-maxillary fossa, the anterior articulates 

 with the maxillary, the internal with the ethmoid, and the posterior, 

 which is small and only exists towards the extremity of the process, 

 articulates with the sphenoidal spongy bone. 



The orbital surface is frequently found enlarged from the union with 

 the palate bone of a portion of bone ossifying from a separate centre, 

 usually united with the ethmoid or sphenoid, and already described with 

 llie sphenoidal spongy bone (p. 40). 



The splunoidal 2n'ocess curves upwards, inwards, and backwards from 

 the posterior part of the vertical plate. Its superior or external surface 

 is in contact with the sphenoidal spongy bone and the base of the 

 internal pterygoid plate, and is grooved for the completion of the 

 pterygo-palatine canal ; its internal or under surface looks to the 

 posterior narcs ; and at its base a third surface looks foi-wards and out- 

 wards into the spheno-maxillary fossa. Its inner extremity is in con- 

 tact with the wing of the vomer. 



The spJumo-palatine foramen is formed in greatest part by the deep 

 notch between the orbital and sphenoidal processes, and is completed 

 above by the sphenoidal spongy bone. It leads from the spheno- 



