Shoulder Impingement Exercises

In this post let’s take a closer look at the shoulder joint, paying close attention to its anatomy and what has to happen for it to function properly.

One of the things most people don’t realize about the shoulder joint is that the only place the arm connects to the rest of the skeleton is the SC joint, i.e. where your collar bone meets your sternum.

Basically the shoulder joint is made up of three bones, the collar bone (also known as the clavicle), the shoulder blade (scapula) and the arm bone (humerus).

The shoulder joint is unlike virtually any other joint in the body in regards to the relationship between the surfaces of the joint. i.e. unlike the knee or the hip where one bone stacks directly on top of the other, in the shoulder the joint surfaces are horizontal to one another.

The shoulder joint is often referred to as a ball and socket joint, meaning that the top of the arm bone provides the ball to the joint, while the shoulder blade provides the cup.

Unlike the hip joint, which is also a ball and socket joint, the socket of the shoulder is small in relation to the ball. A good analogy is to think of a golf ball sitting on top of a golf tee.

This design in shoulder anatomy is actually a good thing as it allows great amounts of movement in multiple directions.

Unfortunately this relationship also means that the joint can not rely on gravity or its bony structures to provide support.

Instead the shoulder relies on a remarkable relationship between the joint capsule, ligaments and muscles to provide movement, stability and a coordinated action between the three bones that make up the shoulder joint.

In order to be able to lift you arm overheard, two-thirds of the movement comes from the movement of the arm bone within the shoulder blade, and the other third comes from the rotation upwards of the shoulder blade.

Thus there are three different groups of muscles that you need to be aware of:

1. The muscles that go from the skeleton to the shoulder blade. These provide both stability and movement for the shoulder blade.
2. The muscles that go from the shoulder blade to the arm bone. The muscles are also referred to as the Rotator Cuff Muscles. These muscles are responsible for making sure the arm bones rotates precisely within the shoulder joint while the shoulder blade is moving.
3. The muscles that connect the skeleton to the arm bone. The muscles are responsible for movement, strength and power.

With all these moving parts it is easy for something to go wrong.

In order to determine if your shoulder is in good condition, painful due to a musculoskeletal problem, or heading towards trouble, it is important to be able to assess the functioning of these 3 different muscle groups.

This is why I stress the importance of a good understanding of shoulder anatomy.

My next post will go into greater detail on what structures within the shoulder joint can become injured. Please feel free to leave a comment if you have further questions.

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