158 APPLIED PHYSIOLOGY 



311. The pelvis. The backbone rests upon a large 

 and strong ring of bone formed by the hip bones. The 

 hip bones form a round bottomless basin called the pelvis, 

 There are three bones in the pelvis, and the joints between 

 them are close fitting and strong. We sit upon the bot- 

 toms of the two hip bones. 



312. The legs. From each side of the pelvis a long 

 bone reaches downward to form the framework of the leg 

 above the knee. This t bone is called the femur, and is 

 the largest, longest, and strongest bone in the body. 



Reaching from the knee to the ankle is a long and 

 strong bone called the shin bone or tibia. Upon its out- 

 side is a long slender bone called the fibula. The lower 

 end of the fibula forms ^the lump of bone which is called 

 the outer ankle bone. The inner ankle bone is formed by 

 a small tongue of bone from the tibia. 



313. The instep. Below the shin bone are seven small 

 rounded bones which are very tightly bound together by 

 strong bands of connective tissue. They form the instep, 

 or arch of the foot. This arch supports the weight of the 

 body while we stand. So it is made very strong. A single 

 bone would not spring, but the whole body would be jarred 

 at every step. The arch is made of several bones each of 

 which will spring a little. So when ,we jump or run, our 

 bodies are but little jarred. The pads between the rings 

 of the spine also keep the body from being jarred. 



At the end of the instep are nineteen slender bones 

 joined end to end in five strings. The first bone of each 

 string is buried in the flesh, and together they form the 

 sole of the foot. They are called tarsal bones. The re- 

 maining bones of each string form the toes. 



314. The shoulder. Two bones at the lower part of the 

 neck upon each side form a frame upon which the arm is 



