72 



THE HUMAN BODY. 



consists in the adult of three pieces, and seen from the ven- 

 tral side has somewhat the form of a dagger. The piece 

 M nearest the head is called the handle or manubrium, 

 and presents anteriority a notch, Id, on each side, with 

 which the collar-bone articulates (u, Fig. 13); farther back 

 are two other notches, Ic 1 and Ic 2, to which the sternal 

 ends of the first and second ribs are attached. The middle 

 piece, C, of the sternum is called the body; it completes 

 the notch for the second rib and has on 

 its sides others, Ic 3-7, for the third, 

 fourth, fifth, sixth, and seventh ribs. 

 The last piece of the sternum, P, is 

 called the ensiform or xiphoid process; 

 it is composed of cartilage, and has no 

 ribs attached to it. 



The Ribs (Fig. 25). There are twelve 

 pairs of ribs, each being a slender curved 

 bone attached dorsally to the body and 

 transverse process of a vertebra in the 

 manner already mentioned, and con- 

 tinued ventrally by a costal cartilage. 

 In the case of the anterior seven pairs, 

 the costal cartilages are attached direct- 

 ly to the sides of the breast-bone; the 

 next three cartilages are each attached 

 to the cartilage of the preceding rib, 

 FIG. 24.-The sternum while the cartilages of the eleventh and 

 twelfth ribs are quite unattached ven- 

 so these are called the free or 

 ribs. The convexity of each 

 curved rib is turned outwards so as to 

 give roundness to the sides of the chest and increase its 

 cavity, and each slopes downwards from its vertebral at- 

 tachment, so that its sternal end is considerably lower than 

 its dorsal. 



The Skull (Fig. 26) consists of twenty-two bones in 

 the adult, of which eight, forming the cranium, are ar- 

 ranged so as to inclose the brain-case and protect the 

 auditory organ, while the remaining fourteen support 



f r the 



