The term 'arm joint' refers to the five major joints of the arm, which are the WRIST, ELBOW, ANKLE, KNEE, and ULNA. The WRIST is a complex joint that connects the hand to the forearm and allows for movement in multiple directions. The ELBOW is a hinge joint that connects the upper arm to the forearm and allows for bending and straightening of the arm. The ANKLE is a hinge joint that connects the lower leg to the foot and allows for up and down movement. The KNEE is a hinge joint that connects the thigh to the lower leg and allows for bending and straightening of the leg. The ULNA is a long bone in the forearm that connects to the ELBOW and helps to stabilize the arm.