Chap. V] 



THE SKELETON 



69 



piece is termed the body, or gladiolus ; the inferior portion is 

 termed the ensiform, or the xiphoid process. On both sides of 

 the upper and middle pieces are notches for the reception of the 

 sternal ends of the costal cartilages. The ensiform or xiphoid 

 process is cartilaginous 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, but affords attachment for some of the abdominal muscles. 

 Ribs (costse) . — They are elastic arches of bone, forming the 

 chief part of the thoracic wall (vide Fig. 45). They are usually 

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

 with the vertebrae, and the first seven pairs are connected with the 

 sternum in front through the intervention of the costal cartilages ; 

 these first seven pairs are called from their attachment the true 

 ribs. The remaining five pairs are termed false ribs; of these, 

 the first three, eight, nine, and ten are attached in front to the 



ANGLE. 



Fig. 47. — The Eighth Rib of the Right Side. Viewed from behind. (Geirish.) 



costal cartilages of the next rib above. The two remaining, being 

 unattached in front, are termed floating ribs. 



The convexity of the ribs is turned outwards so as to give 

 roundness to the sides of the chest and increase the size of its 

 cavity; each rib slopes downwards from its vertebral attach- 

 ment, so that its sternal end is considerably lower than its dorsal, 

 and the lower border is grooved for the accommodation of the 

 intercostal nerves and blood-vessels. The spaces left between the 

 ribs are called the intercostal spaces. 



BONES OF THE UPPER EXTREMITIES 



Clavicle (clavicula, or collar bone) ... 2 



Scapula (shoulder blade) 2 



Humerus (arm) 2 



