The Bones. 1 3 



Composition of Bone. Bone is composed of two thirds 

 mineral matter and one third animal matter ; in childhood 

 the animal matter is in larger proportion, while in old age 

 the mineral matter is in excess. The mineral matter is 

 chiefly phosphate of lime, while the animal matter is 

 largely gelatin. 



Lamellas 



Lacunas 





Canaliculi Haversian Canal 



Fig. 9. Cross-section of Bone. (Highly Magnified.) 



Classification of Joints. i. Immovable, such as the 

 joints between the bones of the skull; 



2. Mixed, such as the joints between the vertebras ; 



3. Movable, which allow free motion between the parts; 



(a) Ball and socket, as in the hip and shoulder ; 



(b) Hinge, as in the knee and elbow ; 



(c) Pivot, as in the forearm, and between the atlas and 

 axis; 



