THE FRAMEWORK OF THE BODY. 



socket joint, is that at the shoulder, possessing a freedom 

 of motion greater than any other in the body. 



Fio. 5. ELBOW JOINT. A, Bone of the arm ; B, C, Bones of the fore-arm. 



11. The Spinal Column. The spjnal column is often 

 spoken of as the " back-bone," as if it were a single bone, 

 while, in reality, it is composed of a chain of twenty-six 

 small bones, called vertebra. The spinal column is a 

 wonderful piece of mechanism. It not only connects the 

 important cavities of the body, as has already been shown, 

 but, also, itself forms a canal, which contains the spinal 

 cord. The joints of the vertebrae are remarkable for the 

 thick layers of cartilage which separate the adjacent sur- 

 faces of bone. The amount of motion between any two 

 of these bones is not great; but these little movements, 

 taken together, admit of very considerable flexibility, in 

 several directions, without endangering the supporting 

 power of the column. 



11. What is the spinal column ? What docs it connect and form ? Joints of 

 the vertebrae ? Amount of motion ? Result ? 



