THE FRAMEWORK OF THE BODY 23 



sets of limbs : the arms, which are attached to the chest by 

 means of the " collar-bone " and " shoulder-blade ; " and the 

 legs, directly joined to the lower part of the trunk. (Bead Note 5. ) 



7. The cavities, three of which we have mentioned, are 

 designed for the lodgment and protection of the more delicate 

 and perishable parts of the system. Thus, the skull, together 

 with the bones of the face, shelters the brain and the organs 

 of four senses sight, hearing, smell, and taste. The chest 

 contains the heart, lungs, and great blood-vessels, while the 

 lower part of the trunk sustains the liver, stomach, and other 

 organs. 



8. The Joints. The point of union of two or more bones 

 forms a joint or articulation, the connection being made in 

 various ways according to the kind and amount of motion 

 desired. The movable joints are connected by strong fibrous 

 bands, called ligaments. These ligaments are of a silvery 

 whiteness, and very unyielding ; so much so, that when sudden 

 violence is brought to bear in the vicinity of a joint, the bone 

 to which a ligament is attached may be broken, while the 

 ligament itself remains uninjured. When this connecting 

 material of the joints is strained or lacerated by an accident, a 

 " sprain " is the consequence. An injury of this sort may be, 



meshes are composed of delicate, but strong, bony partitions, and 

 arranged in such angles to the outer wall and to themselves as will sup- 

 port the greatest weight. 



5. Two Forms of Skeleton among Animals. "The solid basis on 

 which all the soft organs of the body rest is the skeleton. In the human 

 body the skeleton is composed of a number of bones, each of which has a 

 distinct name. In the animal kingdom there are two distinct forms of 

 skeletons ; the one which is found chiefly in the lower animals is outside, 

 and covers the soft parts, and is called an exo-skeleton. Examples of 

 this kind of skeleton are seen in crabs, lobsters, insects, and the shells 

 of mollusca, as oysters, mussels, and whelks. The shells of these animals 

 are mostly composed of carbonate of lime. Fishes possess an internal 

 skeleton ; and all the classes of animals above them, as reptiles, birds, and 

 mammals, possess internal or endo-skeletons." Lankester's Manual of 

 Health. 



1. Design of the cavities ? Give the examples. 



8. Joint or articulation ? Movable joints, how compacted ? The ligaments of the mov- 

 able joints ? What is a sprain ? Consequence of a serious sprain ? 



