CHAP. IV.] 



THE SKELETON. 



33 



FIG. 30. STERNUM. Front and side 

 view. 



portions. It has been likened to an ancient sword. The upper 

 piece, representing the handle, 

 is termed the manubrium or 

 handle ; the middle and largest 

 piece, which represents the chief 

 part of the blade, is termed the 

 gladiolus ; and the inferior piece, 

 which is likened to the point of 

 the sword, is termed the ensiform 

 appendix. On both sides of the 

 upper and middle pieces are 

 notches for the reception of the 

 sternal ends of the ribs. The 

 ensiform appendix is cartilagi- 

 nous in structure in early life, 

 but is more or less ossified at 

 the upper part in the adult: it 

 has no ribs attached to it. The 

 sternum is about six inches long, 

 being rather longer in the male 

 than in the female. 



The ribs are elastic arches of bone, forming the chief part 

 of the thoracic walls (vide Fig. 47). They are usually twelve 

 in number on each side. They are all connected behind with 

 the vertebrae of the spine, and the first seven pairs are con- 

 nected with the sternum in front through the intervention of 

 the costal cartilages : these first seven pairs are called from their 

 attachment the vertebro-sternal, or true ribs. The remaining 

 five pairs are termed false ribs ; of these, the first three, being 

 attached in front to the costal cartilages, are usually called the 

 vertebro-costal, while the two remaining, being unattached in 

 front, are termed vertebral, or floating ribs. The convexity of 

 each curved rib is turned outwards so as to give roundness to 

 the sides of the chest and increase the size of its cavity ; each 

 slopes downwards from its vertebral attachment, so that its 

 sternal end is considerably lower than its dorsal. The spaces 

 left between the ribs are called the intercostal spaces. 



The os innominatum, or nameless bone, so called from bearing 

 no resemblance to any known object, is a large irregular-shaped 

 bone, which, with its fellow of the opposite side, forms the sides 



