The Shoulder Joint In Movement

Let’s break down some real-life shoulder movements

The Shoulder In Movement

In the previous article, What Is The Shoulder Girdle, we looked at the bones, joints, and basic movements of the shoulder girdle. But this only tells us so much about what’s happening at the shoulder joint in real-life movement. In this article we’ll cover what muscles attach to and move the shoulder joint, and we’ll apply that information to understanding movements of the shoulder in some daily life activities and common sports.

To review: the shoulder joint is the ball and socket joint where the humerus (the upper arm bone) meets the depression in the scapula called the glenoid fossa. Its anatomical name is the glenohumeral joint. There are nine muscles that cross the glenohumeral joint, including:

  • Biceps brachii (long head)
  • Triceps brachii (long head)
  • Deltoid
  • Supraspinatus
  • Infraspinatus
  • Teres minor
  • Subscapularis
  • Teres major
  • Coracobrachialis

There are a couple of other muscles that attach to and move the humerus, but don’t attach to the scapula, so they don’t technically cross the glenohumeral joint. However, they still contribute to moving the arm as part of the larger shoulder complex [link to post]. (Remember the whole shoulder complex includes muscles that go from the humerus to the scapula AND the muscles that go from the humerus to the clavicle and cross the acromioclavicular joint.) So, we could also include the following muscles in the group that move the shoulder joint:

If we group the muscles that move the shoulder by action we would have the following lists:

Flexion of the shoulder:

  • Biceps brachii
  • Deltoid (anterior fibers)
  • Pectoralis major

Extension of the shoulder:

Adduction of the shoulder:

Abduction of the shoulder:

  • Deltoid
  • Supraspinatus

Medial rotation of the shoulder:

  • Deltoid (anterior fibers)
  • Teres major
  • Latissimus dorsi
  • Pectoralis major
  • Subscapularis

Lateral rotation of the shoulder:

  • Deltoid (posterior fibers)
  • Teres minor
  • Infraspinatus

Shoulder movements in daily life

So, now that we’ve reviewed the movements of the glenohumeral joint and the muscles that move the humerus, let’s apply our knowledge to a few situations from daily life. Remember though, as we highlight what the shoulder joint is doing in a particular activity, that real-life actions are complex and are almost always a combination of multiple actions at more than one joint.

If you were closing a door by pulling it towards you, then you would be extending the shoulder joint. The muscles involved would include: triceps long head, deltoid (posterior fibers), teres major, latissimus dorsi, and teres minor.

If you were opening a door by pushing it away from you, then you would be flexing the shoulder joint. The muscles involved would include: biceps brachii, deltoid (anterior fibers), and pectoralis major

Shoulder movements in sports

Now let’s take a look at a couple of actions in tennis and some weight-lifting exercises you might do in the gym.

If you were doing a forehand stroke with your racket in tennis, you would be doing horizontal flexion (also called horizontal adduction) and medial rotation at the shoulder. The muscles involved would include: pectoralis major, latissimus dorsi, teres major, subscapularis, and deltoid (anterior fibers).

If you were doing a backhand swing with your racket in tennis, you would be doing horizontal extension (also called horizontal abduction) and lateral rotation at the shoulder joint. The muscles involved would include: teres minor, infraspinatus, and deltoid (posterior fibers).

If you were watching shoulder movements in the gym, you might see lateral movements like abduction and adduction.

If you did a dumbbell lateral raise, you would be abducting your arm at the shoulder. That is, you would raise your arm with the dumbbell laterally to 90 degrees. The muscles involved would include the deltoids and supraspinatus at the start of the movement.

If you did a wide-grip pull-up you would be adducting your arms at the shoulder joints to pull yourself up to the bar. The muscles involved would include primarily: triceps brachii (long head), teres major, latissimus dorsi, and pectoralis major.

As you look at shoulder movements in real-life actions you get an idea of how complex movement really is. If you want to challenge yourself to start applying anatomy, try this process for yourself. Take some real-life movements and see if you can break them down into their anatomical movements.

Do you want to learn more about the shoulder? Check out our previous post, What Is The Shoulder Girdle?