A MANUAL OF ANATOMY 



OSTEOLOGY 



The skeleton is the hard ' dry ' osseous and cartilaginous frame- 

 work of the body. It consists in the adult of 200 bones, exclusive 

 of the small bones of the ear and sesamoid bones, most of which 

 are held together by Ugaments. The functions of the bones are 

 as follows : (i) they impart shape to the body ; (2) they support 

 the soft parts ; (3) they protect important organs ; and (4) thfy 

 afford attachment to the muscles. In the performance of t^r^ 

 latter function the bones are to be regarded as passive organs 01 

 locomotion, the activ^e organs being the muscles — that is to say, 

 the bones act as levers to the muscles. There are two varieties 

 of skeleton, namely, endoskeleton and exoskeleton. * In the former, 

 as in man, the bones are covered by soft parts. In the latter, 

 as in Crustacea, the bones are so disposed as to he upon the surface, 

 where they form a case which contains the soft parts of the animal. 

 The human skeleton is arranged in two divisions, axial and appen- 

 dicular. The axial skeleton comprises the head and trunk, and 

 the appendicular represents the limbs. The head is composed 

 of 23 bones, including the hyoid bone. The trunk is made up 

 of the vertebral column, containing 26 separate bones in adult 

 life ; the sternum ; and the ribs, with their costal cartilages, 

 24 in number, thus making 51 bones in all in the trunk. The 

 appendicular skeleton comprises the two upper or pectoral hmbs, 

 each containing 32 bones, exclusiv'e of sesamoid bones, and the 

 two lower or pelvic limbs, each containing 31 bones, also exclusive 

 of sesamoid bones. 



Descriptive Terms. 



Ankylosis : bony union between two bones which are normally 

 separate. 



Apophysis {' grow from ') : this is any process or swelling on a 

 bone. 



Capitellutn : a small head. 



Caudal : towards the tail. 



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