Final answer:
The long bone of the upper arm is called the humerus, which connects to the shoulder and forearm, forming part of the upper limb.
Step-by-step explanation:
The long bone of the upper arm is known as the humerus. The humerus is the only bone in the upper arm region and plays a crucial role in forming joints with the shoulder at one end and the elbow at the other, where it articulates with the forearm bones, the radius, and the ulna. The upper limb of the human body is divided into three regions with the arm being one of them, consisting of the humerus as its primary structure.