Final answer:
The glenoid labrum is the fibrocartilage structure that increases the depth of the glenoid cavity in the shoulder joint.
Step-by-step explanation:
The fibrocartilage structure that increases the depth of the glenoid cavity is called the glenoid labrum. The glenoid labrum is a small lip of fibrocartilage that extends around the outer margin of the glenoid cavity in the scapula. Its presence deepens the socket and provides stability to the shoulder joint.