AXIAL SKELETON. 63 



and also forms partitions between the muscles, cases for 

 fi'icli organs as the liver and kidneys, and sheaths around 

 the blood-vessels. The bony and cartilaginous framework 

 n r ith its ligaments might be called the skeleton of the 

 organs of the Body, and this finer supporting meshwork the 

 skeleton of the tissues. Besides forming a support in the 

 substance of various organs, the connective tissue is also 

 often laid down as a sort of packing material in the crevices 

 between them; and so widely is it distributed everywhere 

 from the skin outside to the lining of the alimentary canal 

 inside, that if some solvent could be employed which would 

 corrode away all the rest and leave only this tissue, a very 

 perfect model of the whole Body would be left; something 

 like a " skeleton leaf ," but far more minute in its tracery. 



The Bony Skeleton (Fig- 13). If the hard framework 

 of the Body were joined together like the joists and beams of 

 a house, the whole mass would be rigid; its parts could not 

 move with relation to one another, and we would be un- 

 able to raise a hand to the mouth or put one foot before 

 another. To allow of mobility the bony skeleton is made 

 of many separate pieces which are joined together, the 

 points of union being called articulations, and at many 

 places the bones entering into an articulation are movably 

 hinged together, forming what are known as joints. The 

 total number of bones in the Body is more than two 

 hundred in the .adult; and the number in children is still 

 greater, for various bones which are distinct in the child 

 (and remain distinct throughout life in many lower animals) 

 grow together so as to form one bone in the full-grown 

 man. The adult bony skeleton may be described as con- 

 sisting of an axial skeleton found in the head, neck, and 

 trunk; and an appendicular skeleton, consisting of the 

 bones in the limbs and in the arches (u and s, Fig. ]3) by 

 which these are carried and attached to the trunk. 



Axial Skeleton. The axial skeleton consists primarily 

 of the vertebral column or spine, a side view of which is 

 represented in Fig. 14. The upper part of this column is 

 composed of twenty-lour separate bones, each of which is a 

 vertebra. At the posterior part of the trunk, beneath the 



