Why would a self-defense instructor advise a student to strike an attacker’s clavicle?

While fireman Fred is fighting a fire in a building, part of the ceiling collapses, and a beam strikes him on his left shoulder. He is rescued, but has a great deal of pain in his shoulder. He cannot move his arm properly, especially in the anterior direction. His clavicle is not broken, and his humerus is intact. What is the probable nature of Fred’s injury?

At work, a box fell from a shelf onto Ella's acromial region. In the emergency room, the physician felt that the head of her humerus had moved into the axilla. What had happened to Ella?

In anatomical position, the ulna lies:

(a) Medial to the radius

(b) Lateral to the radius

(c) Inferior to the radius

(d) Superior to the radius