Acromion Process and Head of Humerus. Permission Joseph E. Muscolino. Kinesiology - The Skeletal System and Muscle Function, 3rd ed. Elsevier, 2017).

Six Causes of Shoulder Impingement Syndrome – Part 3

Another reason for shoulder impingement syndrome to occur is insufficient elevation of the clavicle. Most of scapular upward rotation is actually caused by elevation of the clavicle at the sternoclavicular joint, so if clavicular elevation is prevented for any reason, shoulder impingement syndrome can occur.

The Pectoralis Minor. Permission Joseph E. Muscolino. The Muscular System Manual - The Skeletal Muscles of the Human Body, 4th ed. (Elsevier, 2017).

Six Causes of Shoulder Impingement Syndrome – Part 2

For scapular upward rotation to occur, scapular downward rotator musculature must lengthen. If scapular downward rotation muscles are tight, they might not be flexible enough to allow for scapular upward rotation, thereby causing shoulder impingement syndrome to occur.