60 THE SKELETON 



.Superiorly this border is terminated l>y tlic orbital process. This process 

 presents tive surfaces; of these, three are artieuhir. The posterior surface joins the 

 walls of the sphenoidal turbinal bone, its air-cells extending occasionally into this 

 part of the palate bone. In the same way the posterior ethmoidal cells extend into 

 the inner surface of the orbital process, where they articulate with the lateral mass. 

 The anterior surface is a continuation of the outer aspect of the A'ertical plate, and 

 rests upon the maxilla. O! the two non-articular surfaces, the one directed 

 upwards and outAvards is slightly concave, and forms part of the floor of the 

 orbit at its junction with the inner wall. The outer smooth surface looks 

 directly into the zygomatic fossa, extends into the spheno-maxillary fossa, and 

 forms the anterior boundary of the spheno-palatine foramen. These surfaces 

 are often conveniently named according to the bones with which they articu- 

 late, or the fossae which they help to form: thus, the anterior or maxillary; 

 internal or ethmoidal ; posterior or sphenoidal ; superior or orbital ; external 

 or zygomatic. 



Between the orl)ital and sphenoidal processes is the spheno-palatine notch, 

 which is converted by the sphenoidal turbinal into a complete foramen. Occa- 

 sionally it is complete in the palate bone. It transmits the spheno-palatine nerve 

 and artery; the foramen opens into the back part of the nasal fossa, close to its 

 roof. When the spheno-palatine foramen is complete in the palate bone, it is 



Fig. 71. — Palate Bone. (Posterior view.) 



ORBITAL SURFACE — 



ORBITAL PROCESS 

 ZYGOMATIC SURFACE ^^SISK^i.- (SURFACE FOR SPHENOIDAL TURBINAL) 



SPHENO-PALATINE FORAMEN 

 (USUALLY A NOTCH) 



GROOVE FOR EXTERNAL PTERYGOID 



SPHENOIDAL PROCESS 



GROOVE FOR PTERYGOID FOSSA 

 GROOVE FOR INTERNAL PTERYGOID f:^ — {& i^^ SPINE OF PALATE 



often due to ankylosis between the palate and the sphenoidal turbinal; the latter, 

 being extremely fragile, easily breaks during the process of disarticulation. 



Articulations.— The palate bone articulates Avith its fellow, the sphenoid, 

 maxilla, vomer, sphenoidal turbinal, inferior turbinal, and ethmoid bones. As tin- 

 surfaces and lines of union of the orbital and sphenoidal processes are somewhat 

 intricate, the student should, when studying this bone, refer to the following 

 figures. The orbital and zygomatic surfaces are shown in fig. 80. The relation of 

 the sphenoidal process to the nasal fossa in fig. 61. The relations of the pterygoid 

 processes to the tuberosity of the palate are shown in fig. 81. ^\'ith the help of 

 these drawings the student will be aV)le to understand the position of this bone, 

 which assists in forming the boundary of the following cavities: viz. the nasal, 

 orbital, spheno-maxillary, and antral; and the ethmoidal cells. 



The muscles attached to it are: — 



Internal pterygoid. Tensor palati. Azygos uvute. 



Superior constrictor of pharynx. 



Blood-supply. — Its arteries are derived from the descending palatine, the 

 spheno-i»alatinc. and pterygo-palatine. 



Ossification. — The palate bone arises from one nucleus, which is deposited in 

 membrane, and appears about the eighth week of embryonic life. The sjiot where 

 the carthv matter is first seen ultimatelv becomes the angle where the vertical and 



