Question

Rotation of arm in a full circle is possible due to ............ joint

• A. Ball and sockets
• B. Gliding
• C. Pivot
• D. Hinge

Answer 1

The correct option is A Ball and sockets

• The arm is joined to the shoulder girdle/ pectoral girdle by the ball and socket type of joint. The ball and socket joint is the strongest type of joint in the human body. It provides a maximum rotation of 360 degrees i.e full circle/ circumvention. This makes possible the rotation of the arm in a full circle.
  
• Gliding joint is also known as a plane joint or planar joint. It is a common type of synovial joint formed between bones that meet at flat or nearly flat articular surfaces. These joints are found in the articulations between the bones of the wrist and those of the ankle.
• Pivot joint is a type of synovial joint, also called rotary joint, or trochoid joint. It is freely moveable joint (diarthrosis) that allows only rotary movement around a single axis. Example: pivot joint between radius and ulna of the forearm.
• The hinge joint is a common class of synovial joint that includes the ankle, elbow and knee joints. Maximum rotation is 180 degrees.

Thus, rotation of the arm in a full circle is possible due to ball and socket type of joints.