The term 'PART OF THE ARM' can be broken down into two crossword solutions: ULNA (4 letters) and WRIST (5 letters). The ULNA is one of the two long bones in the forearm, located on the medial side of the arm. It runs from the elbow to the WRIST and is the larger of the two bones. The WRIST is the joint between the hand and the forearm. It is composed of eight small bones and is a complex joint that allows for movement in multiple directions.