Answer:
The correct answer to the question: Downward slippage of the humeral head when relaxed may indicate an injury to the:_____ muscle, would be: the supraspinatus muscle.
Explanation:
The supraspinatus muscle, along with other major muscles, like the deltoid, help to provide stability to the shoulder joint and prevent the humeral head of the arm, from detaching from the glenoid cavity at the shoulder joint. Particularly during abduction of the arm, the supraspinatus muscle will adhere the head of the humerus towards the glenoid cavity, and prevent the bone from naturally falling away in a downward motion, from the cavity. When there is a lession to this muscle, there tends to be dislocation of the shoulder joint.
