Rotator Cuff Anatomy Essentials

Rotator cuff anatomy can not be viewed in isolation. The rotator cuff is an integral part of the shoulder and it must be looked at accordingly.

The shoulder is an incrdible joint. It is one of the most complicated features within the body. This is an examination not only of how the shoulder and the rotator cuff work together but also how they are constructed .

I will discuss how the shoulder works and provide an overview of the complexities of rotator cuff anatomy. Hopefully, in doing so I can answer a few of the common questions. Questions such as How is the rotator cuff constructed? What does each of the rotator cuff muscles do? What is its major purpose?

Shoulder instability is one of the major causes of shoulder or rotator cuff pain. Indeed, a fair proportion of injuries, such as a rotator cuff tear or impingement of the rotator cuff, can be blamed on this same instability.

The shoulder is a ball and socket joint similar to the hips but it has a much more open aspect. It is a complex formation of bones, ligaments, muscles and tendons. It provides a great range of motion for your arm. The only downside to this extensive range of motion is a lack of stability. This instability is what makes the shoulder joint vulnerable to injury.

Why is the shoulder so potentially unstable? The physical characteristics of the "ball" and particularly the "socket" is the major contributor. The Glenhoid Fossa of the scapula into which the rotator cuff holds the humeral head of the upper arm is very shallow, very similar to a saucer. As a consequence, the humerus is not fitted in snugly and securely. It can, therefore, ride up, or move excessively, particularly if the rotator cuff muscles are weak. .

Let's take a detailed look at the shoulder.

The shoulder is made up of three bones, and the four rotator cuff muscles. The bones are called the

Shoulder blade - Scapula
Upper arm bone - Humerus
Collarbone - Clavicle

Also present in the shoulder are a range of other features such as bursa that enable the tendons to glide smoothly and the acromion but they are not significant features.

The four muscles that connect the shoulder joint are collectively called the rotator cuff. Individually they are

Supraspinatus
Infraspinatus
Teres Minor
Subscapularis

It is the contracting and lengthening of these muscles and tendons that help to move your arm.

In the top picture above, three of the four muscles are visible the Infraspinatus, the Supraspinatus, and the Teres Minor. These are the muscles which are viewed from the rear, or "posterior". The Subscapularis is not visible because it can only be viewed from the front, or "anterior".

Each of the four rotator cuff muscles has a distinct role to play in controlling, not only, arm movement but also shoulder stability. That is why damage or an injury to any one muscle affects the performance of the whole shoulder.

The rotator cuff muscles have two primary roles within the shoulder, namely, stability and movement. The have to work together to hold the humerus securely, whilst at the same time, enabling the joint to work through its great range of motion.

Rotator cuff anatomy is unique in the human body. It is amazing to think that four relatively small muscles such as these have such an impact on our everyday lives. There is no other joint like the shoulder. Certainly not a joint that allows such a large range of motion whilst, at the same time, generating the power of which the arm is capable.