206 FIBROUS SYSTEM. 



../?. It is not. The ligaments intermix with it, serve as 

 a means of communication, and thus is it continued. 



Q. What bony parts are destitute of it? 



-ft. The crown of the tooth, and the bony projections 

 on the heads of animals. 



Q. What different morbid processes take place when 

 the medullary substance and periosteum are diseased ? 



ft. In the disease of the medullary substance, necrosis 

 seizes the whole bone; in that of the periosteum, the ex- 

 ternal laminae are alone affected. 



Q. What is the direction of the fibres of the perios- 

 teum? 



ft. It is that of the fibres of the long and short bones, 

 but not radiated as the fibres of the flat bones are. 



Q. Are the fibrous organs inserted into the periosteum, 

 or are they more immediately connected with the bone? 



ft. In infancy they are not connected with the bone; 

 but as ossification progresses, it attaches the inner layers of 

 the fibrous organs, and thus firmly supports the powerful 

 action of the muscular lever. 



Q. What are the uses of the periosteum ? 



ft. It protects the bones from the action of surround- 

 ing parts: it assumes the ossific process when disease 

 destroys the bones : by the ossification of its inner layers it 

 increases the thickness of the bones: but above all, it af- 

 fords to the fibrous organs a general, solid, resisting sup- 

 port 



Of the Fibrous Capsules. 



Q. Where are they found? 



ft. Almost exclusively on the scapulo-humoral and 

 ilio-fe moral articulations. 



