128 A MANUAL OF ANATOMY 



The interpalatal suture connects the mesial borders of the hori- 

 zontal plates of the palate bones. It is continuous with the inter 

 maxillary suture, and is a harmonic suture. 



The transverse palato-maxillary suture connects the anterior 

 border of the horizontal plate of the palate bone with the posterior 

 border of the palatal plate of the superior maxilla. Its direction 

 is transverse, it is continuous with its fellow of the opposite side, 

 and it is a finely serrated suture. 



The vertical palato-maxillary suture connects the lower part of 

 the anterior border of the perpendicular plate of the palate bone 

 with the interna] surface of the superior maxilla behind the opening 

 of the antrum of Highmore. It is a harmonic suture. The orbito- 

 palato-maxillary suture will be described under the orbital sutures. 



The incisor or premaxillary suture is usually of temporary dura- 

 tion. It connects the incisor or premaxillary part of the superior 

 maxilla with the superior maxilla proper. It extends from a point 

 immediately behind the lower end of Stensen's canal to the alveolar 

 border at a point between the lateral incisor and canine alveoli, its 

 direction being outwards and forwards. It is always present in 

 early life, and traces of it may be present in adult life on the inferior 

 surface of the palatal plate of the superior maxilla. 



The pterygo-maxillary suture connects the lower part of the 

 anterior border of the pterygoid process of the sphenoid with the 

 lower part of the posterior border of the superior maxilla. Its 

 direction is vertical, and it is a harmonic suture. The pterygo- 

 maxillary fissure lies above it. 



The petro-squamosal suture connects the petrous and squamous 

 parts of the temporal bone, and is situated on the internal or cere- 

 bral surface of the bone. Its direction is antero-posterior, and it 

 extends from the petro-squamosal angle anteriorly to the parietal 

 notch (entomion) on the superior border of the pars mastoidea pos- 

 teriorly, where it meets the squamo-mastoid suture. It is a har- 

 monic suture, and ankylosis usually takes place in the course of the 

 first year of hfe. The suture, however, may persist until puberty, 

 or later. Even though ankylosis takes place at the normal period 

 of time, it may occur in such an imperfect manner that the suture 

 is drilled by several channels. Under the foregoing circumstances 

 pyogenic infection may extend from the tympanic cavity to the 

 cerebral meninges and brain. The petro-squamosal venous sinus of 

 foetal life extends along the petro-squamosal suture. 



The squamo-mastoid suture connects the mastoid and squamous 

 parts of the temporal bone, and is situated on the external surface 

 of the bone. Its direction is almost vertical, and it extends from 

 the parietal notch (entomion) on the superior border of the pars 

 mastoidea anteriorly to a point behind the posterior limb of the 

 tympanic annulus. The lower part of the suture intervenes between 

 the contiguous part of the pars mastoidea and the post-meatal plate 

 of the pars squamosa, which latter forms the supra-meatal triangle 

 and outer wall of the antrum. Superiorly it meets the petro- 



