The Rotator Cuff is a fascinating and complex structure. With its muscles and tendons, it is designed to stabilize our shoulder. It is a crucial part of the human anatomy because it helps to suspend the entire upper limb from the rest of the body, and allows all of our shoulder movements. As a massage therapist, it is important to know how the Rotator Cuff is designed and how exactly it functions. The majority of my clients suffer from some type of shoulder pain or discomfort, and damage to the Rotator Cuff is one of the most common causes.
To understand how the cuff works, we must understand its anatomy. The Rotator Cuff is comprised of your Shoulder Joint, 4 muscles and a ligament. The Shoulder Joint, otherwise known as the Glenohumeral Joint is a Synovial Ball and Socket Joint. We have many types of joints in our bodies and they all serve different purposes for different functions. The Rotator Cuff was designed for a wide variety of movements and this type of joint makes these movements possible. Synovial Joints allow for this extra mobility because the cavities between bones in a synovial joint are filled with synovial fluid. This fluid helps to lubricate and protect these bones in motion. Below is a posterior view of the Glenohumeral Joint.
It’s obvious why this joint is called a Ball and Socket. The white part of the Humerus or the upper arm bone, looks like a ball and it fits into the Scapula or shoulder blade, which looks like a socket.
Listed below are the various movements of the Shoulder Blade:
- Flexion – Forward movement
- Extension – Backward movement
- Abduction – Taking the arm away from the body
- Adduction – Pulling the arm towards the body
- Medial Rotation – Wrapping your arms around yourself
- Lateral Rotation – Unwrapping your arms
Because the rotater cuff allows for so many movements, it is easy to imagine how many injuries can occur to the shoulder.
The Coracohumeral Ligament is the ligament responsible for connecting the Humerus to the Scapula. It is a broad band of connective tissue that fastens the Humerus to the Scapula. Its function is to strengthen the superior portion of the joint capsule. In other words, it is the only ligament that is anchoring the bones together. The illustration below shows, again from a posterior view, how the ligament attaches and connects to the Humerus and Scapula.
Next, let’s take a closer look at the muscles that make up the Rotator Cuff. The various muscles that cross the shoulder joint, which generate movements of the Humerus, can be divided into four groups:
- Rotator Cuff Muscles
- Shoulder Cap Muscles
- Intertubercular Muscles
- Brachial Muscles
Focusing on the Rotator Cuff group, there are only four:
- Supraspinatus – A small muscle that sits right on top of the shoulder. It runs along the superior edge of the Scapula and ends on the upper portion of the Humerus (upper arm.) However, it is not a superficial muscle and runs deep to the Trapezius. The Supraspinatus is responsible for abducting the arm at the shoulder. This muscle is damaged in 80% of rotator cuff injuries.
- Infraspinatus – Located on the posterior surface of the scapula and like the Supraspinatus, ends on the top of the head of the Humerus. Closer to the spine, this thick, triangular muscle is superficial, but the lateral half is deep to the Deltoid muscle. The main function of the Infraspinatus is to externally rotate the arm and stabilize the shoulder joint.
- Teres Minor – This narrow, elongated muscle attaches to the lateral edge of the scapula and top of the head of the Humerus. It is located directly superior to the Teres major and deep to the Deltoid. The Teres Minor helps to laterally rotate the shoulder joint and arm.
- Subscapularis – This muscle is similar to the Infraspinatus, but instead of covering the posterior surface of the scapula; instead, it covers the anterior surface. It is sandwiched between the scapula and the muscles that lie between each rib (Serratus Anterior). The Subscapularis makes up part of the wall of the armpit. This muscle helps the shoulder to medially rotate.
Starting from the left, the first 3 photos are from a posterior view and the last illustration is positioned from an anterior view.
Now that the structure and functions of each part of the Rotator Cuff have been explained, it is important to know what common symptoms to look for if an injury or tear occur in the cuff:
- Shoulder ache
- Limited range of motion
- Sharp, shooting pain
- Discomfort/pain radiating down the arm
And of course, if a sudden tear is ever felt in the shoulder, a muscle or ligament in the cuff could have a partial tear. If a tear is suspected, watch for inflammation of the area and make sure to give your shoulder rest. If you or somebody you know is suffering from shoulder pain/tightness, call me today to set up a bodywork session. The Rotator cuff muscles may simply need to be released. Call me today @ 801.349.3934 to schedule a massage in Salt Lake City, Utah.