Читать книгу The House We Live In; or, The Making of the Body онлайн

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Percy: They have joints so they can move many ways.

Mother: You may all put your arms out straight. Now raise them above your head and then touch your head without bending them.

Helen: We can’t do it, mother.

Mother: Let us see, then, how many joints, or bending-places, we have. We will call them the hinges of our house, for they help us to use our limbs, just as the hinges of a door help us to open or close the door. Please bend your arm and tell me how many parts it has.

Percy: My arm has two parts.

Mother: What do you think would be a good name for the part near your shoulder?

Amy: The top arm, or upper arm.

Mother: I think upper arm is best. Now if that part is the upper arm, what would you call the other part?

Elmer: The lower arm.

Mother: It is also called the forearm. Now move your elbow joint backward and forward, and tell me what kind of joint it is.

Helen: It is like a door hinge, for I can move it only two ways.

Mother: Yes, the elbow joint unites the upper and lower arm, and it can swing only one way. What shall we call the joint that joins the upper arm to the shoulder?