Range of motion of the shoulder joint

The shoulder joint is the most mobile and movable joint in the body. It allows movement in all directions and gives bigger range of motion than other joints. But there are limits to be aware of. In this post, I will discuss the main components of the shoulder joint and the safe range of motion. 

The shoulder joint acts like an articulation point for shoulder bones which facilitates the movement of the arm. The shoulder joint has a total of four joints: glenohumeral joint (rotation), acromioclavicular joint (upward/downward rotation), sternoclavicular joint (forward/backward rotation) and scapulothoracic joint (flexion/extension). It is also made up of four main bones: scapula (shoulder blade), clavicle (collar bone), humerus (upper arm bone), acromion (acromioclavicular joint), and glenoid (shoulder socket). These bones are connected by cartilage and ligaments and held in place by muscle, tendons and a thin layer of fat. 

So the shoulder joint is a ball and socket joint formed by two bones, the upper arm bone (humerus) and the shoulder blade (scapula). The socket of the joint is lined with a connective tissue called cartilage, which allows for smooth and painless gliding of the bones relative to each other. The ball part of the joint is formed by the head of the humerus which fits into the socket of the scapula. There are two main ligaments attached to the ball and socket of the shoulder joint which hold it together. 


The safe range of shoulder joint movement is as follows:

• Abduction: 180 degrees
• Adduction: 45 degrees
• Flexion: 180 degrees
• Extension: 60 degrees
• Horizontal Adduction: 45 degrees
• Horizontal Abduction: 135 degrees

​Shoulder rotation beyond the safe range of motion could cause injuries like shoulder impingement or rotator cuff tears. And because the shoulder joint is the most mobile joint in the body, that makes it very prone to injuries. It is very important that you, as an aqua instructor or just a user of aquatics, understand the limits of your joints before performing exercises in the pool.