Question

which kind of joint allows the arms to swing in circles?

○ hinge

○ ellipsoidal

○ ball-and-socket

○ sliding

Explanation:

To determine the joint that allows arms to swing in circles, we analyze each option:

• Hinge joints (e.g., knee, elbow) allow only angular movement in one plane, not circular swinging.
• Ellipsoidal joints allow movement in two planes but not full circular motion.
• Ball - and - socket joints (like the shoulder joint) have a rounded end (ball) fitting into a cup - like socket. This structure enables movement in multiple planes, including the circular motion needed for swinging arms in circles.
• Sliding joints (e.g., in the wrist) allow gliding movements, not circular swinging.

Answer:

C. ball - and - socket