21* OUTLINES OF EQUINE ANATOM^ 



PART II— OSTEOLOGY. 



THE SKULL, 



with a few cartilaginous accessory structures, forras tlie 

 basement structure of the head. It is composed of modi- 

 fied vertebrae, united together in such a manner as to form 

 numerous cavities, mostly for the purpose of protecting 

 important organs. It is a conical body, the apex part or 

 muzzle, of which we shall consider as being directed for- 

 wards, the base towards the trunk to which it is united by 

 the neck. It is divided into the cranium, which corre- 

 sponds to the neural portion of the other vertebrae, and the 

 face, which is antero-inferiorly placed, and corresponds to 

 the haemal ring. The latter much predominates in size. 



THE CRANIITM 



consists of twelve bones, four pairs and four single. The 

 cavity formed by these bones will be considered when its 

 contents are to be examined ; we shall here examine as 

 distinct bones those osseous masses which, in the adult, 

 are firmly united into a single mass with those of the face 

 forming the upper jaw. The lower jaw is formed by a 

 special bone of the face (the inferior maxillary bone). 

 The union between the upper and lower jaws, and that 

 ])etween the cranium and the first cervical vertebra, are 

 the only examples of synovial articulations to be found 

 in the skull. The union of os hyoides (the tongue bone) 

 with the base of the skull is fibro-cartilaginous. All the 

 other joints are immoveable, and sooner or later become 

 obliterated. 



OS OCCIPITIS is the postero- superior bone of the 

 cranium, that which articulates with the atlas, and which 

 forms the "poll." It is divided into hody, condyles, basilar 

 procesSf and styloid 'processes. It is a single bone lying 



