The bone of the arm located above the elbow joint, which is the large arm, is called the humerus and is the thickest and longest bone in the arm. Below the elbow joint, which is the small arm, there are two elongated tubular bones, the bone on the side of the thumb is called the radius and the bone on the side of the little finger is called the ulna. The hemispherical part of the proximal humerus is called the humeral head and forms the shoulder joint with the articular glenoid of the scapula, while the distal humeral glide and humeral tuberosity form the elbow joint with the ulnar eminence and radial tuberosity. There is also an axle-like joint between the ulna and the radius, called the proximal radial-ulnar joint, which consists of the annular articular surface of the radial tuberosity and the radial notch of the ulna.