To form a ball and socket joint, the structure labeled I fits into another structure in the scapula called the

Answer Details

The structure labeled "I" refers to the head of the humerus bone in the upper arm. In the scapula, which is a bone in the shoulder blade, the structure that receives the head of the humerus is called the glenoid cavity. The head of the humerus fits into the glenoid cavity, creating a ball and socket joint. This joint allows for a wide range of movements in the arm, including rotation, flexion, and extension.