FACE. 



209 



low groove for lodging the posterior palatine 

 nerves and vessels. The nasal portion of the 

 internal surface is placed above the palatine 

 process, and is lined on its anterior three-fourths 

 by the pituitary membrane. Tracing this sur- 

 face from before backwards we observe, 1. the 

 lower aperture of the naso-lachrymal canal, 

 situate just behind the inferior turbinated crest 

 of the nasal process ; 2. posterior to this, the 

 ori/icr ()/ tin' maxillary siuus, or untrum of 

 liighmore, which in the sepaiated bone is a 

 large opening, but is contracted in the united 

 face by the lachrymal, the ethmoid, the palate, 

 and the inferior turbinated bones, which are 

 attached around its margin. Above this aper- 

 ture are seen some cells which unite with those 

 of the ethmoid, and its lower edge presents a 

 faiure in which is received the maxillary pro- 

 cess of the palate-bone. Below the inferior 

 turbinated crest, the naso-lachrymal canal and 

 the orifice of the antrum, the bone is concave 

 and smooth, and forms a part of the inferior 

 meatus of the nose; behind this smooth surface 

 and the orifice of the antrum, the bone is 

 rough for the attachment of the vertical plate 

 of the os palati, and it presents a groove, which, 

 descending obliquely forwards to the palatine 

 division of this surface, forms a part of the 

 posterior palatine canal. 



I'lii' maxillary sinus (sinus jinn ill/iris, antrum 

 Ilig/imori; Germ, die OberkieJ'erhohle) oc- 

 cupies in the adult the whole body of the 

 bone : its form is triangular, with the base 

 directed internally towards the orifice which 

 has been already described, and the apex out- 

 wards towards the malar process. Its superior 

 wall is formed by the orbitar plate; the pos- 

 terior corresponds to the maxillary tuberosity ; 

 and the anterior to the canine fossa. All 

 these walls present ridges or crests, which 

 lodge canals for the passage of nerves. The 

 posterior and anterior walls contain the - 

 perior, anterior, and posterior dental canals, 

 which lodge nerves of the same name. The 

 upper wall contains the infra-orbitar groove 

 and canal, which gives passage to the upper 

 maxillary nerve. 



Borders. 1 . The anterior or naso-maxillary 

 border is united above along the nasal process 

 to the nasal bone. Below this it is thin and 

 presents a deep semicircular notch, which forms 

 the lateral and inferior portions of the anterior 

 aperture of the nose. At the lower extremity 

 of this notcli the bone projects, and forms 

 with its fellow of the opposite side the anterior 

 nasal spine. The remainder of this border 

 proceeds downwards and a little forwards to 

 terminate on the alveolar border of the bone 

 between the two middle incisor teeth. 



2. The posterior or pterygo-palatine border, 

 thick, rounded, and vertical, is united below 

 to the palate bone, and above it forms, with 

 the palate bone, the anterior border of the 

 pterygo-maxillary fissure. 



3. The inferior or alveolar border is thick 

 and broad, especially behind, and forms about 

 the fourth of an oval. It is perforated with 

 conical cavities (alveoli) for the reception of 

 the roots of eight teeth. Thesp cavities are 



VOL. II. 



separated by thin transverse laminae. Tracing 

 them backwards from the anterior extremity 

 of the border, the orifices of the two first 

 are nearly circular, and receive the incisors ; 

 they are the largest, and are placed below the 

 nasal notch. The third, in form transversely 

 oval, receives the canine tooth, is of great 

 depth, and ascends in front of the canine fossa. 

 The fourth and fifth, also transversely oval, 

 but not so deep, receive the lesser molar 

 teeth ; they generally present ridges in their 

 septa which correspond to grooves in the fangs 

 of the teeth which are implanted into them. 



The orifices of the three last cavities are 

 quadrilateral, and receive the molar teeth. 

 The sixth and seventh are subdivided into 

 three lesser cavities, of which the two external 

 are smaller than the inner one. Sometimes 

 one of the molar teeth has four fangs, and 

 then we find its socket subdivided into a cor- 

 responding number of cavities. The eighth 

 alveolus, which receives the last molar tooth 

 or dens sapientix, is not so distinctly divided 

 into subordinate cavities, but presents ridges 

 like the lesser molar. The outline of the 

 alveolar border is waving, convex where it 

 corresponds to the alveoli, and depressed op- 

 posite their septa. The whole of this border 

 is covered by the gums, and presents innu- 

 merable pores for the nutritious vessels. The 

 surfaces of the alveoli are also similarly 

 marked. 



Conner ions. The upper maxillary articu- 

 lates with two bones of the cranium, viz. the 

 ethmoid and frontal, and sometimes with the 

 sphenoid by its pterygoid processes, or by an 

 union of the orbitar plates of both bones at 

 the outer extremity of the spheuo-maxillary 

 fissure. In this case the malar bone does not 

 enter into the formation of this fissure. The 

 upper maxillary articulates with its fellow 

 and with all the bones of the face. The me- 

 dian and lateral cartilages of the nose are at- 

 tached to it. It receives the upper teeth, and 

 gives attachment to eight muscles, viz. the 

 orbicularis palpebrarum, the inferior oblique 

 of the eye, the levator labii superioris alaeque 

 nasi, the levator labii proprius, the depressor 

 alee nasi, the compressor narium, the levator 

 anguli oris, and the buccinator; often also 

 to some of the fibres of the temporal and 

 the external pterygoid muscles. It lodges the 

 naso-palatine ganglion, and gives passage to 

 the infra-orbitar and to the anterior and pos- 

 terior palatine and dental vessels and nerves. 

 It forms the greater part of the sides of the 

 nose, and of the floor of that cavity, and 

 of the orbit, as well as of the roof of the 

 mouth. It contains the maxillary sinus and the 

 nasal duct. 



Structure. This bone is lighter than might 

 be expected from its size, being occupied by the 

 large antrum maxillare. It is cancellous only 

 at the tuberosity, along the alveolar border, 

 and at the malar and palatine processes. 



Developemenl. The ossification of this bone 

 commences as early as the thirtieth or thirty- 

 fifth day of foetal life, near its alveolar border, 

 and it is complete -it birth. It prevent-, at 



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