I'ACli. 



211 



dowuwaids, outwards, und Backwards, from 

 the angle of union of (lie posterior U.rders of 

 tlie vertical and horizonUil plates of the bone. 

 This process is the /}/i n/^nnl or /ii/riiiniihil, and 

 PIVM IMS ilnre '.'.moves behind, viz. one inli-rnul 

 and one e ,(ti mat, (of which the inner is the 

 deeper,) for the reception of the anterior borders 

 of the lower extremity of the pterygoid plates; 

 and a middle triangular groove extending high 

 up, and which forms a part of the pterygoid fossa. 

 The outer surface of this process is rough, 

 and is articulated with the upper maxillary 

 bone: its apex is continuous with the external 

 pterygoid plate. 



The inftrior border is united to the horizon- 

 tal plate. 



1 he superior border presents a deep semi- 

 circular notch (sometimes a hole), which with 

 the sphenoid bone above forms the spheno- 

 palutinej'orumcn. This notch divides the upper 

 border into two processes, 1 . the posterior (the 

 sphenoidal) ; 2. the anterior (the orbitar). The 

 sphenoidal process is curved inwards and back- 

 wards, and has three surfaces, 1. an internal or 

 nasal, forming part of the cavity of the nose ; 

 2. an external, which forms below the spheno- 

 palatine foramen the deep wall of the pterygo- 

 maxillary fissure ; 3. an upper, which is con- 

 cave and rests against the body of the sphenoid 

 bone, and contributes to the pterygo-palatine 

 canal. 



The orbitar process stands upwards and 

 outwards on a narrow neck, and presents five 

 surfaces. 1. The anterior (or maxillary) arti- 

 culates with the upper maxillary bone. 2. The 

 internal (or ethmoidal) forms a cell which unites 

 with those of the ethmoid. 3. A posterior 

 (or sphenoidal) presents a cell uniting with the 

 sphenoid, and communicating with its sinuses. 

 4. The superior (or orbitar), which is smooth 

 and contributes to form the floor of the orbit : 

 its posterior border forms a part of the spheno- 

 maxillary fissure, and separates the orbitar sur- 

 face from, 5. the external or zjgomatic, which 

 looks into the pterygo-maxillary fissure. 



Connexion*. Each palate bone articulates 

 with five bones, viz. two of the cranium, the 

 sphenoid and the ethmoid ; and with three of 

 the face, the upper maxillary, the inferior turbi- 

 nated, and the vomer, besides its fellow bone of 

 the opposite side. It is lined with the buccal 

 and pituitary membrane. It contributes to form 

 the cavities of the mouth, nose, and orbit ; the 

 pterygo-maxillary fissure, and the zygomatic and 

 pterygoid fossaa. It gives attachment to the 

 soft palate, and passage to the spheno-palatine, 

 pterygo-palatine, and posterior palatine vessels 

 and nerves ; also to the two pterygoid muscles, 

 the circumflcxus palati, the levator uvulae, the 

 palato-glossus, and the palato-pharyngeus. 



The structure is compact, except at its pte- 

 rygoid process, where it is cancellous. 



Developement. It is complete at birth, ex- 

 cept that the vertical plate is short to corre- 

 spond with the short vertical diameter of the 

 upper maxillary. About the third month 

 ossification appears in a single point, at the 

 junction of the two plates with the pyramidal 

 process. 



iir Unnes (ussa mulrr v. matuita v. tugo- 

 ; Fr. 01 dc in luinwutti- ; (Jenn. ilte 

 Jochbeine oder Backenbeme). These !,!<, 

 corresponding in situation to the prominence of 

 the cheeks, are somewhat of a quadrilateral 

 figure. Each presents three surfaces; 1. on 

 external or facial; 2. an internal or temporo- 

 zygomatic; 3. a superior or orbitar. There 

 are besides four borders and four angles. 



TheJ'acial surface forms the eminence of the 

 cheek, looks outwards and forwards, is smooth 

 and slightly convex in front, and is marked by 

 one or more small holes (malar foramina), 

 which give passage to vessels and nerves. It ii 

 covered above by the integuments and the orbi- 

 cularis palpebrarum, and below and externally 

 it gives attachment to the zygomatic muscles. 



The temporo-zygomutic surface is smooth 

 and concave below ; and internally there is a 

 rough surface which rests on the malar process 

 of the upper maxillary : about the centre or to- 

 wards the upper part of this surface is observed 

 the internal orifice of a malar canal or a malar 

 hole. The temporal muscle is attached to this 

 surface. 



The orbitar surface is smooth, concave, and 

 is formed upon a plate of bone (the orbitar 

 process), which stands inwards, and contributes 

 to the outer wall and floor of the orbit : its op- 

 posite surface above makes part of the tempo- 

 ral fossa. On the orbitar surface we observe 

 the orifice of a malar canal. The orbitar pro- 

 cess has an irregular summit, which receives 

 the frontal bone ; below, it is articulated with 

 the outer border of the orbitar plate of the 

 sphenoid ; in the middle it corresponds to the 

 extremity of the spheno-maxillary fissure ; and 

 inferiorly it is united to the outer border of the 

 orbitar plate of the upper maxillary bone. 



Of the four borders two are anterior and two 

 posterior. The anterior superior, or the orbi- 

 tar, is smooth, concave, and forms the outer 

 and lower third of the base of the orbit. The 

 anterior inferior, or the maxillary, rests upon 

 the malar process of the upper maxilla from iu 

 extremity to the inferior orbitar foramen. The 

 posterior superior, or temporal border, is waved 

 like the letter S, and gives attachment to the 

 temporal fascia. The posterior inferior, or 

 masseteric border, is thick, and gives attach- 

 ment to a muscle of the same name. The four 

 angles are, 1. thick, rough, superior or frontal, 

 which receives the external angular process of 

 the frontal bone; 2. the interior or orbitar, 

 which is pointed ; and, 3. the inferior or malar, 

 which is round, and forms the extremities of 

 the maxillary border, and which rests on the 

 malar process of that bone. The posterior or 

 zygomatic is cut obliquely from above down- 

 wards and backwards, and supports the zygo- 

 matic process of the temporal bone. 



Connexions. The malar is connected with 

 and locked between four bones, viz. the frontal, 

 the sphenoid, the upper maxillary, and the 

 temporal. It contributes to form the orbit, the 

 temporal, and the zygomatic fossa. It gives 

 attachment to four muscles, viz. the temporal, 

 the masseter, and the two zygomatic ; and it 

 gives passage to malar vessels and nerves. 



p 2 



