44 



ELEMENTARY PHYSIOLOGY 



communicate with each other, and with the Haversian canals, by means o* 

 very minute canaliculi which radiate from them in all directions. 



If the section of bone be made longitudinally instead of transversely, then 

 the Haversian canals will be opened along their length, as they run in the 

 direction of the long axis of the bone. They will then be seen to branch and 

 communicate with one another. 



The Haversian canals are well supplied with blood-vessels. The canali- 

 culi and lacunae take up the nutrient matter from the blood, and distribute it 

 throughout the bone. 



SUMMARY. 



BONE. 



COMPOSITION 



Mineral Matter 



Animal Matter 



STRUCTURE. 



Short bones . 

 Flat bones . 



Irregular bones 



Long bones . . - 



May be dissolved out by acid. 

 Forms the bone ash when a bone is 



burnt. 

 Forms about two-thirds the weight 



of bone. 



Least in the flexible bones of a child. 

 Most in the brittle bones of aged 



persons. 



Less in the sternum and scapula. 

 Resembles cartilage h flexible and 



elastic. 



Yields gelatine on boiling. 

 Forms generally about one-third 



the weight of bone. 



(Humerus, Radius, 

 Examples \ Ulna, Femur, Tibia, 

 I Fibula. 



.Articulating portion, 

 covered with smooth 

 cartilage. 



J Thin compact tissue. 

 Filled with cancellous 

 * tissue. 



(Thick compact tissue. 

 Shaft . -j Often contains a medul- 

 [ lary cavity. 

 ( Composed of blood-ves- 



Marrow - se ^ s anc ^ ^ at ' 



I Supported ty delicate 



I connective tissue. 

 Examples Bones of wrist and ankle 

 Thin compact tissue. 

 Filled with cancellous tissue. 



j Frontal, Parietal, 



\ Occipital. 



I Layer of cancellous 



Composed of J ~ hss " e ' 



Iwo layers of com- 



( pact tissue. 

 Examples Vertebra. 

 Structure Similar to short bone?. 



Heads 



Examples 



