160 



OSTE01 



The nasal surface (Fig. 158) presents a large, irregular opening leading into the 

 maxillary sinus. At the upper border of this aperture are some broken air cells, 

 which, in the articulated skull, are closed in by the ethmoid and lacrimal bones. 

 Below the aperture is a smooth concavity which forms part of the inferior meatus 

 of the nasal cavity, and behind it is a rough surface for articulation with the per- 

 pendicular part of the palatine bone; this surface is traversed by a groove, com- 

 mencing near the middle of the posterior border and running obliquely downward 

 and forward; the groove is converted into a canal, the pterygopalatine canal, by the 

 palatine bone. In front of the opening of the sinus is a deep groove, the lacrimal 

 groove, which is converted into the nasolacrimal canal, by the lacrimal bone and 

 inferior nasal concha; this canal opens into the inferior meatus of the nose and 

 transmits the nasolacrimal duct. More anteriorly is an oblique ridge, the concha! 

 crest, for articulation with the inferior nasal concha. The shallow concavity above 

 this ridge forms part of the atrium of the middle meatus of the nose, and that 

 below it, part of the inferior meatus. 



Anterior 

 ethmoidfil foramen 



Posterior ethmoidal foramen 

 Orbital process of palatine 

 I Optic foramen 



Sphenopalatine foramen 



Sella turcica 

 Probe in foramen rot undum 



Fossa for 



lacrimal sac 



Uncinate process 

 of ethmoid 

 Openings of 

 maxillary sinus 

 Inferior nasal 

 concha 



/Probe in pterygoid canal 

 Probe in pterygopalaline canal 



Palatine bone 

 Lateral pterygoid plate 



Pyramidal process cf palatine 



Fio. 159. Left maxillary sinus opened from the exterior. 



The Maxillary Sinus or Antrum of Highmore (sinus maxillaris). The maxillary 

 sinus is a large pyramidal cavity, within the body of the maxilla: its apex, directed 

 lateralward, is formed by the zygomatic process; its base, directed medialward, 

 by the lateral wall of the nose. Its walls are everywhere exceedingly thin, and 

 correspond to the nasal orbital, anterior, and infratemporal surfaces of the body 

 of the bone. Its nasal wall, or base, presents, in the disarticulated bone, a large, 

 irregular aperture, communicating with the nasal cavity. In the articulated 

 skull this aperture is much reduced in size by the following bones: the uncinate 

 process of the ethmoid above, the ethmoidal process of the inferior nasal concha 

 below, the vertical part of the palatine behind, and a small part of the lacrimal 

 above and in front (Figs. 158, 159) ; the sinus communicates with the middle meatus 



