SECTION 1 



OSTEOLOGY 



By J. BLAND SUTTON, F.E.C.S. 



ASSISTANT-SURGEON TO THE MIDDLESEX HOSPITAL, AND SURGEON TO THE CHELSEA HOSPITAL FOR WOMEN, LONDON 



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THE SKELETON 



THE skeleton contains 206 distinct bones. Tliey are arranged by anato- 

 mists in two sets: — the bones of the trunk and the bones of the limbs. Tlie 

 skeleton of the trunk is made up of the skull, which contains twenty-nine 

 bones exclusive of the teeth; the vertebral column, consisting of twenty-six separate 

 bones; twenty-four ribs, and the sternum. The skeleton of the upper limbs 

 comprises sixty-four bones; and that of the lower limbs, including the patelhe, 

 sixty-two. 



Several of the skull bones are compound, that is, in the immature skeleton they 

 consist of separate elements which ultimately unite to form a single bone. In 

 order to comprehend the nature of such bones, it is necessary to examine them in 

 the various stages through which they pass in the embryo and child. Thus the 

 student, anxious to convince himself of Man's place in nature, studies carefully the 

 development and ossification of l)ones, and compares them with the bones of other 

 \'ertel)rata. He then finds that many elements which make a compound bone are 

 osteological units for the Comparative Anatomist. 



Com})arisons of this nature constitute the science of Morphology, one of the 

 most fascinating departments of Biology. 



It is the duty of the student to follow the descriptions with the actual bones in 

 his hand. He should also remember that many variations occur in the outlines 

 and markings of bones. Hence the various types descril)ed and figured represent 

 the average of a large number of bones examined. It is very rare to meet with 

 bones which accurately correspond to the description in every detail. 



In order to appreciate the mor])hology of the skeleton, the osteogenesis or mode 

 of development of bones must be studied as well as their topography or position. 

 Some 1)ones arise by ossification in membrane, others in cartilage. In the early 

 eml)ryo, many portions of the skeleton are rei)resented by cartilage which becomes 

 infiltrated by lime salts — calcification. This earthy material is taken uj) and 

 redeposited in a regular manner — ossification. Portions of the original cartilage 

 persist at the articular ends of bones, and, in young bones, at the epiphysial lines. 

 Long bones increase in length at the epiphysial cartilages, and increase in thick- 

 ness by ossification of the deeper layers of the investing membrane or periosteum. 

 These jirocesses — intercartilaginous and intermembranous ossitieation — proeee(l con- 

 currently in the limb-l)ones of a young and growing mammal. 



Tliere is no bone in the human skeleton whicli. thougli pre-f<irmed in cartilage, 

 is perfected in tliis tissue. The ossification is completed in mi-mbrane. On the 

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