2:"^.'? 



THE SKELETON 



HUMERUS A 



girdle. In each ilium is a deep socket into which fits the 

 round head of the upper leg bone. 



Like the arms, the legs are attached to the axial skel- 

 eton by a girdle of bones, but, unlike the pectoral girdle, 

 this pelvic girdle is very rigid, and the movements of the 

 legs are confined to the bones of these members. 



The arms and legs. — The bones of the arms and legs 

 correspond very closely in number and arrangement. The 



upper part of the arm 

 contains a single long 

 bone (the humerus), the 

 upper end of which is 

 jointed at the shoulder 

 to the surface of the 

 clavicle and scapula. 

 To the lower end of the 

 humerus are jointed two 

 bones {radius and ulna) 

 which form the forearm, 

 and this joint is called 

 the elbow. 



In the leg the upper 

 bone, or femur, is jointed 

 to the pelvic bones; it 

 corresponds in position to the humerus of the upper 

 arm, but the socket where it joins the ilium (the hip 

 joint) is much deeper than the shoulder joint. The join- 

 ing of the two bones of the lower leg to the lower end 

 of the femur forms the knee. These bones are called the 

 tibia and fibula. While the radius and ulna are of nearly 

 equal size, the tibia, on the contrary, is much larger than 

 the fibula, and forms the main support of the lower leg. 



[-RADIUS 



CARPALS- 

 METACARPALS-2 

 PHALANGES^ 



TARSALS 



■METATARSALS 

 PHALANGES 



Fig. 91 — Bones of tlie leg and the arm. 



