Final answer:
The glenoid labrum is the fibrous ring that surrounds the rim of the glenoid fossa to deepen the articular cavity. It provides stability and helps to deepen the socket formed by the glenoid cavity.
Step-by-step explanation:
The fibrous ring that surrounds the rim of the glenoid fossa and deepens the articular cavity is called the glenoid labrum.
It is a small lip of fibrocartilage that extends around the outer margin of the glenoid cavity, which is the shallow depression located on the lateral scapula. The glenoid labrum provides stability and helps to deepen the socket formed by the glenoid cavity, allowing for smooth movement at the shoulder joint.