What type of joint is found in the shoulder and allows for a wide range of motion?
A. Hinge joint
B. Ball-and-socket joint
C. Pivot joint
D. Gliding joint
Answer (1)
The shoulder joint is an example of a ball-and-socket joint, which is the most mobile type of joint in the human body. It allows for movement in almost every direction — forward, backward, sideways, and in a circle (called circumduction). This joint structure consists of a rounded ball at the end of one bone (the head of the humerus) that fits into a cup-like socket (the glenoid cavity of the scapula).Because of this shape, the shoulder can perform:Flexion and extension (raising/lowering the arm)Abduction and adduction (moving the arm away from or toward the body)Rotation (twisting the arm inward or outward)Circumduction (circular motion)The hip joint is another example of a ball-and-socket joint, though it’s more stable and less mobile than the shoulder. The shoulder sacrifices some stability for maximum range of motion, which is why shoulder dislocations are common.To contrast:Hinge joints (like the elbow and knee) move in one direction (like a door).Pivot joints allow for rotation (like turning your head).Gliding joints (like those in the wrist) allow bones to slide past each other.
