BONES AND JOINTS OF THE EXTREMITIES 53 



of the body the muscles are excited to stiffen the 

 otherwise loose joints, and to poise the body on 

 its base. 



OF THE FOOT 



Let us take the arrangement of the bones of 

 the foot, according to the demonstration of the 

 anatomists. 



They are divided into the tarsus, which is com- 

 posed of seven bones, reaching from the heel to 

 the middle of the foot. The metatarsus, which 

 consists of five long bones laid parallel to each 

 other, and extending from the tarsus to the roots 

 of the toes. The bones of the toes are called 

 phalanges, from being in the form of a phalanx. 



There are in all thirty-six bones in the foot ; 

 and the first question that naturally arises is, 

 Why should there be so many bones ? The an- 

 swer is, In order that there may be so many 

 joints ; for the structure of a joint not only per- 

 mits motion, but bestows elasticity. 



A joint then consists of the union of two bones, 

 of such a form as to permit the necessary motion : 

 but they are not in contact : each articulating 

 surface is covered with cartilage, to prevent the 

 jar which would result from the contact of the 

 bones. This cartilage is elastic, and the cele- 

 brated Dr. Hunter discovered that the elasticity 

 was in consequence of a number of filaments closely 

 compacted, and extending from the surface of the 



