An athletic was playing footbal one evening. Later, he was slammed backwards into the upright edge of the penalty box. The jolt pushed the head of his humerus forward, dislocating his right shoulder. He turned around and slammed his own arm against the wall so that the humerus was pushed back into place. For several weeks afterwards the range of motion in his right arm was much less than on the left. He did not tell his parents what happened or they would have taken him to see an orthopedic surgeon. 1. With the help of the x-ray describe the bony structures of the shoulder joint.

2. Define range of motion (ROM) and

explain how the bony structure of the

shoulder normally allows for a large range

of motion.

3. Define stability and explain why the structure of the shoulder does not give it great inherent stability.

4. Discuss the structures (e. g., ligaments and cartilage that are important to keeping the humeral head in the glenoid cavity.

Specifically, what structures prevent anterior displacement of the humeral head?

5. Suggest how these structures may have been overcome resulting in dislocation of the humerus