CHAPTER V 



THE SKELETON 



Function. — The bones are the principal organs of support, and 

 the passive instruments of locomotion. Connected together in the 

 skeleton, they form a framework of hard material, affording at- 

 tachment to the soft parts, maintaining them in their due posi- 

 tion, sheltering such as are of delicate structure, giving stability 

 to the whole fabric, and preserving its shape. 



The entire skeleton in the adult consists of two hundred and six 

 named bones. These are : — 



Cranium 8 



Face 14 



f Malleus 2 



Ear Incus 2 6 



[ Stapes 2 



Hyoid 1 



The spine, or vertebral column 

 (sacrum and coccyx included) 26 



Sternum and ribs 25 



Upper extremities 64 



Lower extremities 62 



206 

 In this enumeration the sesamoid^ bones, which are found em- 

 bedded in tendons covering the bones of the knee, hand, and foot, 

 are not included. 



CLASSIFICATION 



The bones may be divided, according to their shape, into four 

 classes: 1. Long, 2. Short, 3. Flat, and 4. Irregular. 



Long bones. — A long bone consists of a shaft, and two extrem- 

 ities. The shaft is formed mainly of compact tissue, this compact 

 tissue being thickest in the middle, where the bone is most slender 



1 Ses'amoid [from the Greek sesamon, a "seed of the sesamum " and eidos, "form," 

 "resemblance"], resembling a grain of sesamum. 

 E 49 



