208 



FACE. 



infra-orbitar) /cMset, which gives attachment to 

 the levator anguli oris, and at the upper part of 

 which is seen the infra-orbitar foramen, giving 

 exit to the vessels and nerves of the same 

 name ; 4. the malar ridge, a semicircular crest 

 which descends vertically from the malar pro- 

 cess to the alveolar border of the bone, and 

 divides its facial from its zygomatic surface, 

 which is prominent behind, where it forms the 

 maxillary tuberosity, most conspicuous before 

 the exit of the last molar tooth, which in the 

 child is lodged within it. On this surface are 

 several small holes, (posterior dental fora- 

 mina,) which are the orifices of canals for the 

 posterior and superior dental vessels and 

 nerves. 



From the upper and front part of the ante- 

 rior surface of the bone a long vertical process 

 (the nasal process) ascends between the nasal 

 and lachrymal bones to be united with the 

 frontal ; its external surface is rough, presenting 

 small irregular holes, which transmit vessels to 

 the cancellous interior of the bone and to the 

 nose, and giving attachment to the levator labii 

 superioris alaeque nasi muscle. The internal sur- 

 face of this process is marked with some minute 

 grooves and holes for vessels, and, tracing it 

 from below upwards, by a transverse ridge or 

 crest (the inferior turbinated ridge) for the 

 lower spongy bone ; above this by a depres- 

 sion corresponding to the middle meatus ; next 

 by a crest (the superior turbinated ridge) 

 for the upper spongy bone of the ethmoid; 

 and above this by a surface which receives 

 and completes some of the anterior ethmoid 

 cells. The nasal process has three borders: 

 1. an anterior, thin and inclined from 

 above downwards and forwards; above, it is 

 cut obliquely from the internal towards the 

 external surface of the bone, and below in the 

 contrary direction, so that this edge of the 

 nasal process and the corresponding border of 

 the nasal bone with which it is united, mutu- 

 ally overlap each other. 2. A poster tor border, 

 or surface, thick and divided into two margins 

 by a deep vertical groove (the lachry mo-nasal 

 canal) which contributes to lodge the lachrymal 

 sac above, and the nasal duct below. The 

 direction of the lachrymo-nasal canal is curved 

 from above downwards and outwards ; so that 

 its convexity looks forwards and inwards, and 

 its concavity in the contrary direction. The 

 inner margin of this groove is thin, and is 

 united above to the anterior border of the os 

 unguis, and below to the inferior spongy bone. 

 The outer margin is bounded and gives attach- 

 ment to the tendon and to some of the fibres of 

 the orbicularis palpebrarum ; it commonly ter- 

 minates below in a little tubercle (the lachrymal 

 tubercle). 3. The upper border of the nasal 

 process, which is short, thick, and irregular, is 

 articulated with the internal angular process of 

 the frontal bone. 



The orbitar surface of the bone is the small- 

 est; it is quadrilateral, smooth, and slightly 

 concave, with an inclination from above down- 

 wards and from within outwards ; it forms the 

 greater part of the floor of the orbit. Along 

 the middle of its posterior half runs, in a direc- 

 tion forwards and outwards, the infra-orbitar 



groove, which anteriorly becomes a complete 

 canal (the infra-orbitar canal), and finally 

 divides into an internal or larger canal, which 

 terminates at the infra-orbitar hole in the 

 canine fossa, and into an external or small 

 conduit, which runs in the anterior wall of the 

 antrum, and conveys the superior anterior den- 

 tal nerves to the incisor and canine teeth ; this 

 outer subdivision of the canal presents several 

 varieties in different individuals. The orbitar 

 surface (or plate) has four borders: 1. The 

 posterior, which, free and notched in the mid- 

 dle by the commencement of the infra-orbitar 

 canal, forms with the orbitar plate of the sphe- 

 noid and palate bones the inferior orbitar or 

 the spheno-maxillary fissure. 2. The internal, 

 which articulates from behind forwards succes- 

 sively with the palate, the ethmoid, and the 

 lachrymal bones. 3. The anterior, short and 

 smooth, separates the orbitar from the facial 

 surfaces of the bone; at its inner extremity is 

 the nasal process already described. 4. The 

 external is united to the malar bone ; on the 

 outer side of this border is a rough triangular 

 projecting surface (the malar process) which 

 receives the os malae, and which forms an 

 angle of union between the anterior, posterior, 

 and superior surfaces of the upper maxillary 

 bone. 



The internal or naso-palatine surface is di- 

 vided along the anterior three-fourths into two 

 unequal parts by an horizontal plate of bone 

 (the palatine process) : above this is the nasal 

 portion forming the upper three-fourths of 

 this surface, and below it, is the palatine 

 part which forms the remaining fourth. The 

 palatine process forms the anterior three- 

 fourths of the floor of the nose, and roof of the 

 mouth; it presents a smooth upper surface, 

 concave transversely, and nearly flat in the op- 

 posite direction : it is broad behind and narrow 

 in front, where there is placed the orifice of the 

 anterior palatine canal, which takes a direction 

 downwards, forwards, and inwards, unites with 

 the corresponding canal in the opposite bone 

 at the median plane, and forms a common 

 canal (the canalis incisivus), which opens below 

 by a hole (the foramen incisivum) on the roof 

 of the mouth, immediately behind the middle 

 incisor teeth. The anterior palatine canals and 

 the incisive canal, which are often included to- 

 gether under a common name, form a tube re- 

 sembling the letter Y, being bifid above and 

 single below. The inferior surface of the pa- 

 latine process is rough and concave, and forms 

 the anterior and larger part of the roof of the 

 mouth ; its internal border is long and rough, 

 thick in front, narrow behind, and united with 

 the corresponding border of the opposite bone 

 forms the maxillary suture : this border is sur- 

 mounted by a half-furrow which, with that of its 

 fellow bone, forms a groove for the reception of 

 a part of the vomer. The posterior border is short 

 and cut obliquely at the expense of the upper 

 surface ; it supports the anterior margin of the 

 horizontal part of the palate-bone. The pala- 

 tine division of the internal surface of the upper 

 maxillary bone is narrow, and forms part of 

 the arched roof of the mouth ; along its junc- 

 tion with the palatine process is a broad shal- 



