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?
Percy: The shoulder joint.
Mother: Is this joint like the one in your elbow?
Helen: No, for I can swing my arm backward or forward or any way I like.