T8 



HITCHCOCK'S ANATOMY 



Column. — A large number of bones in the spinal column is 

 necessary in order to give flexibility to the body. Were the 

 number considerably less, the movements of the trunk would 

 be attended with much more difficulty than at present, and be 

 devoid of grace. And were the separated vertebrae long 

 bones, they would be much more easily broken, thereby en- 

 dangering the spinal marrow. Another reason for the great 

 number of these bones, is the necessity of the elastic cartilage 

 between them, to protect the brain. Were the joints fewer, 

 in order to give equal protection to the brain from jars, this 

 cartilage must of necessity have been greatly thickened, 

 thereby weakening the joint, and injuring it as a central axis 

 of support to the whole body, and also increasing the liabil- 

 ity to dislocations, as well as greatly endangering life, by 

 pressure upon the spinal cord. 



172. Use of the Clavicle. — The value of the clavicle lies 

 in keeping the upper extremity in its proper position, so as 

 to prevent the humerus from coming forward towards the 

 middle portion of the body. By its direct resistance it also 

 assists in some muscular actions, such as lifting heavy weights 

 with the hands. 



173. Need of two Bones in the Pore -Arm. — The use of 



two bones in the fore-arm, as already mentioned, is to pro- 

 duce the movements of supination and pronation. And since 

 these movements are of primary importance, and one bone 

 can not answer this end, two are provided. Again, if one be 

 fractured, the other will act as a splint for keeping the broken 

 one in place, greatly superior to the artificial splint, because the 

 natural splint needs no compression. 



174. Why several Bones in the Carpus. — In the carpus 

 are found eight bones, and yet we know there is but little 

 motion between them. The reason why exactly this number 



171. What is the reason why so many bones are placed in the spinal column? What 

 is the nse of the intervertebral substance ? 172. What service does the clavicle render 

 to the upper extremities? 173. Why are there two bones in the fore-arm? 174. What 

 can be said of the many bones of the carpus ? 



