How many limbs have you?—"Four."
How many parts has your arm?—"Two parts: my upper arm and my fore-arm."
How many parts has your leg?—"Two parts: my thigh and my lower leg."
How many joints has your arm?—"Three joints: my shoulder joint, my elbow joint, my wrist joint."
How many joints has your leg?—"Three joints: my hip joint, my knee joint, my ankle joint."
What are joints?—"Bending places."
How many kinds of joints have you?—"Two: hinge joints, and ball-and-socket joints."
What kind of a joint is the shoulder joint?—"A ball-and-socket joint."
Why do you call the shoulder joint a ball-and-socket joint?—"Because at the shoulder the arm may move in any direction."
Tell how the shoulder joint is made.—"The upper end of the bone of the upper arm is rounded and fastened in a hollow place called a socket."