ANATOMY IX A NUTSHELL. 549 



ward. It has three articular surfaces and two free surfaces. The articular 

 surface- are the anteriob or maxillary, which articulates with the superior 

 maxillary bone. — internal or ethmoidal surface, which articulates with the 

 ethmoid hone. — and posterior or sphenoidal surface, winch articulate.- with 

 the sphenoidal turbinated bone. The free surfaces are the orbital, which 

 forms part of the Moor of the orbit. — ami Tin: external or zygomatic surface, 

 which forms part of the zygomatic fossa. This process has a rounded border 

 which forms part of the spheno-maxillary fissure. 



The sphenoidal process is -mailer than the orbital process and articulates 

 .superiorly with the body of the sphenoid, and externally with the pterygoid 

 process of the sphenoid. It has three surfaces and two borders. Tin: internal 

 surface, which is concave, forms part of the outer wall of the nasal 

 fossa— the superior surface, which articulates with sphenoidal turbi- 

 nated bone, is converted into the pterygo-palatine canal, — Tin: external 

 surface articulates with the inner surface of the pterygoid process of the 

 sphenoid bone, and also help.- to form the spheno-maxillary fossa. Its ANTER- 

 IOR border forms the back part of the spheno-palatine foramen. Its pos- 

 terior border articulates with the inner surface of the pterygoid process. 



Ossification. — This bone ossifies from one center. 



Articulation. — It articulates with six bones. The sphenoid, ethmoid, 

 superior maxillary, inferior turbinated, vomer, and its fellow. 



Attachment of Muscles. — This bone has four muscles attached to it. 

 The Tensor palati of the soft palate. Azygos uvulae of the soft palate. Internal 

 pterygoid of the pterygo-maxillary region, and Superior constrictor of the 

 pharynx. 



Blood Supply. — Descending palatine, spheno-palatine, and pterygo- 

 palatine. 



1. Tensor palati, which has been described on page 522. 



2. Internal pterygoid muscle, which has been described on page 529. 



3. Azygos uvulae. — Description. — There is a pair of these muscles although 

 from the name we might think there is but one. There is one on each side 

 of the median line of the soft palate. 



Origin. — From the nasal spine of the palate bone and the adjacent apo- 

 eurosis of the soft palate. 



I nsertk i\. Into the uvula. 



Action. — To shorten the uvula. 



Nerve Supply.— Internal branch of spinal accessory, through the pharyn- 

 geal plexus. 



Bloob Supply. — Palatine arteries from internal maxillary. 



4. Superior constrictor, which has been described on page 515 



LESSON CLXXXVII. 

 Hyoid Bone. (Plate XIX). 

 The hyoid bone, which is situated a1 the base of the tongue consists 

 body, two greater cornua, two lesser cornua, making it horse-shoe in shape. 



It is called the lingual bone. The anterior surface of tin- body is convex and 



