PHYSIOLOGY. 17 



mixed with an earthy matter (phosphate of lime). Their 

 structure is varied, being, in the long bones, compact in the 

 middle, with a central cavity, and the extremities spongy ; 

 while in the flat bones it is lamellated on the external sur- 

 face, but the internal substance is cellular. The bones are 

 divided, according to their form, into long, flat and thick. 

 The first are found in the limbs, the second about cavities, 

 the third wherever mobility and solidity are to be united. 



The bones are connected among themselves by approxi- 

 mation, without any intervening substance forming sutures, 

 by cartilaginous t substance, by tendinous bands (ligaments), 

 in the movable articulations enclosing a cavity in the form of 

 a sac : these are termed capsular ligaments. 



The place of union in bones is called articulation ; of this 

 there are two kinds, movable and immovable ; upon the sur- 

 faces of bones articulated in the former manner certain re- 

 sisting substances are found resembling a kind of animal 

 pasteboard; these are denominated cartilages. A liquid 

 called synovia moistens them and facilitates their move- 

 ments. 



The Head 



Comprehends the cranium and face. The cranium or 

 skull consists of eight bones, which form a cavity for con- 

 taining the brain. These bones, which are flat, are the 

 frontal before ; the occipital behind and below ; the parietal 

 at the sides and above ; the temporal at the sides and -below ; 

 the sphenoid before and below ; and the ethemoid in the ante- 

 rior part of the base of the cranium. The face consists of 

 the upper and lower maxillce or jaws ; the upper jaw contains 

 six pair of bones, and one single bone, and sixteen teeth. 

 These are the two superior maxillary, the two nasal, the two 

 ossa ungues, the two molar, the two palate, the two spongy 

 bones, and the vomer, which last forms the partition of the 

 nose. 



The lower jaw has but one bone besides the teeth ; it is 

 the inferior maxillary bone. 



The Trunk 

 Consists of the spine, the thorax and the pelvis. 



