Full guide to the Rotator Cuff

The rotator cuff is a group of four muscles and their tendons located in the shoulder joint, playing a crucial role in stabilizing and facilitating various movements of the shoulder. The muscles that make up the rotator cuff are the supraspinatus, infraspinatus, teres minor, and subscapularis. Together, paired with the deltoids, these muscles make up the shoulder and are responsible for its versatile movement. Being able to perform 6 different forms of movement, the rotator cuff helps to protect and maintain the main shoulder joint, known as the glenohumeral joint. Let’s take a look at these four muscles and their relation to the shoulder.

Functions and Movements

1. Supraspinatus: Located on the top of the shoulder blade, it is primarily responsible for shoulder abduction much like the lateral deltoid. The supraspinatus plays a crucial role in the initiation of this movement, especially during the first 15 degrees of abduction, before the deltoids take over.
2. Infraspinatus: Positioned on the back of the shoulder blade, like the Teres Minor, the primary function of this muscle is to externally rotate the arm. External rotation involves turning the arm outward, away from the body’s midline
3. Subscapularis: Positioned on the front of the shoulder blade (scapula), it facilitates the internal rotation of the arm. Internal rotation is when you turn your arm inwards, towards the body’s midline. While the primary role is internal rotation, the subscapularis also assists in adduction, which involves bringing the arm back towards the body.
4. Teres Minor: Much like the Infraspinatus, the Teres Minor aids with the external rotation of the shoulder. At the same time, these muscles also aid with the adduction and abduction of the shoulder.

The primary function of the rotator cuff muscles is to keep the head of the humerus (upper arm bone) within the shallow socket of the shoulder blade (glenoid), providing stability and coordination during arm movements. All of the muscles above contribute to the stability of the shoulder joint.

The Bigger Picture

One often overlooked but useful aspect of rotator cuff health is scapular (shoulder blade) movement and positioning. The scapula plays a significant role in the proper function of the rotator cuff muscles and can lead to many issues if not functioning properly. The scapula should move smoothly and coordinate with arm movements. During activities like lifting or reaching, proper scapular retraction (pulling the shoulder blades together) and protraction (spreading the shoulder blades apart) are essential. Remembering to retract the scapula will be very useful when we go to train the rotator cuff.

But beyond the specific functions of the rotator cuff, the mobility of the shoulder joint is needed for overall well-being. Since the shoulder is involved in every movement of the arm. From an athletic standpoint, a strong and mobile rotator cuff is needed to prevent injury and to stabilize the shoulder when performing explosive overhead movements and heavy pressing or lifting. Regular, controlled movement of the shoulder joint helps in the distribution of synovial fluid, which lubricates and nourishes the joint. Maintaining shoulder health can contribute to reducing the risk of degenerative conditions like arthritis. So we must keep our shoulders strong and able.

For other guides in the Chest & Shoulder region, read our Complete guide made simple!