Beneath the larger muscles of the shoulder joint is a smaller, more subtle arrangement of muscles types.
Each one of these originates from the scapula and inserts on the upper aspect of the humerus.
Although they are not capable of generating much force, they play a fundamental role in stabilizing and controlling movement at the shoulder joint. This group of muscles are often referred to as rotator cuff muscles and as stabilisers of the shoulder joint; the integrity and coordinated function of these muscles reduces the potential for injury at the joint. The muscles of the rotator cuff are:
This runs laterally from the scapula to the humerus and helps with adduction and external rotation.
This runs superiorly from the scapula to the top of the humerus and helps with shoulder abduction.
This runs laterally from the scapula (slightly higher than the teres minor) to the humerus. It helps with horizontal extension, external rotation and adduction.
This runs from the underside of the scapula to the front of the humerus and helps with internal rotation and adduction.
The key thing to remember is that the rotator cuff muscles are important stabilisers of the shoulder joint.