PECTORAL ARCH. 



sides of the chest and are united in 

 front to the sternum, or breastbone, d, 

 Fig. 8. 



Skull, hyoid bone, vertebral column, 

 ribs, and sternum together form the 

 axial skeleton. 



The appendicular skeleton consists 

 of the pectoral and pelvic girdles, at- 

 taching the limb bones to the axial 

 skeleton ; and of the bones of the limbs 

 themselves. 



The pectoral arch or girdle consists 

 on each side of a clavicle or collar-bone, 

 u, and a scapula or shoulder-blade, 

 which latter is a flat, triangular bone, 

 lying on the back of the chest outside 

 the ribs. The clavicle is a slender curved 

 bone like an italic /in form. Its outer 

 end is attached to the scapula, and 

 its inner end to the top of the sternum. 

 It serves to brace out and support the 

 shoulder- joint, and to prevent it from 

 fulling downwards and inwards toward 

 the front of the chest. It is absent 

 in beasts which use their fore limbs 

 for walking only, as horses, dogs, and 

 cattle, but is well developed in mon- FIG. 9. -side view of the 



.epmal column. 



keys and bats. 



Name the parts which make up the axial skeleton ? 



Of what main divisions does the appendicular skeleton consist? 

 What bones exist in the pectoral arch ? Where does each lie? What 

 is its shape? Name some animals which have no collar bones, and 

 some which have them. 



