Final answer:
The small hollow beneath the arm where it joins the body at the shoulders is known as the glenohumeral joint. This joint is formed by the articulation between the glenoid cavity of the scapula and the head of the humerus.
Step-by-step explanation:
The small hollow beneath the arm where it joins the body at the shoulders is known as the glenohumeral joint.
This joint is formed by the articulation between the glenoid cavity of the scapula and the head of the humerus.
The glenoid cavity is a shallow socket that allows for a large range of motion at the shoulder joint.