You may have heard of the scapula before, though it is more commonly called the shoulder blade. Scapulas play a very important role in the way your arms, shoulders, and back move.
What Is the Scapula?
The scapula is a triangle-shaped bone positioned at the back of your shoulders. Many different muscles are anchored to this shoulder blade bone.
Despite the bone being a solid piece, there are several parts of the scapula. Some of the key scapula parts include:
- Acromion: the bony tip of your shoulder blade that connects with your collarbone and helps stabilize the shoulder joint
- Coracoid process: a hook-shaped part of the top of the scapula that extends over the shoulder to help stabilize the shoulder joint along with the acromion
- Glenoid cavity: a depression in the side of the scapula where the glenohumeral joint, the joint that connects the scapula to the upper arm bone, sits
Other important areas of the scapula include fossas (or, depressions) in the scapula, angles, and borders, where muscles and fibers attach to the scapula.
Where Is the Scapula Located?
The scapula is located behind the shoulders. It’s attached to the humerus (the upper arm bone) via a ball-and-socket joint called the glenohumeral joint.
Ball-and-socket joints are joints where the round surface of one bone (in this case, the humorous) sits within the depression of another bone, which in this case is the scapula. Ball-and-socket joints offer the most mobility of all the joint types. The hip joint is another example of a ball-and-socket joint.
The scapula is also attached to the clavicle, which is commonly known as the collarbone, through the acromioclavicular joint. The acromioclavicular joint is a planar joint sometimes referred to as a gliding joint. Gliding joints allow for a limited range of motion and do not rotate.
What Does the Scapula Do?
The scapula permits a range of motion for the shoulder. It serves as part of the shoulder joint and as an anchor for many of the arm, upper back, and shoulder muscles. Scapula function depends on these muscles, which include the:
- Levator scapulae. You have one of these muscles on either side of the back of your neck along your spine. The levator scapulae lift the scapula, allowing you to shrug your shoulders.
- Rhomboids. Rhomboids are a group of muscles that stretch across your back from your spine to your scapula. These muscles retract the shoulder blades, allowing you to pinch the shoulder blades together, as well as rotate your scapulas down, allowing you to lower your arms from an overhead position.
- Serratus anterior. The serratus anterior muscles are muscles that stretch across your first eight ribs. The muscle starts at your sides and reaches across the back to the scapula. These muscles allow you to round your shoulders forward.
- Upper trapezius. The trapezius muscle is a large, diamond-shaped muscle in your back. It stretches from the base of your neck down to the middle of your back, as well as across your shoulders. The upper trapezius covers the neck and tops of the shoulders. It allows you to shrug your shoulders and lift your arms overhead.
- Middle trapezius. The middle trapezius stretches across your shoulders. It helps you pinch your shoulder blades together and lift your arms overhead.
- Lower trapezius. The lower trapezius is the bottom “V” of the diamond-shaped muscle. It allows you to push your shoulders downward.
Scapula Disorders and Conditions
Your scapula is key to proper movement of your arms and shoulders. When something goes wrong, it can cause difficulty with movement.
Scapular dyskinesis is the term used for abnormal function or mobility of your scapula. This can occur due to many things, including:
- Imbalance, tightness, weakness, and occasionally detachment of the muscles that control your scapula
- Injury to the nerves of these muscles
- Injury to bones in the shoulder joint or bones that support your scapula
Examples of scapular dyskinesis include conditions such as:
- Shoulder impingement syndrome: a condition where your rotator cuff, a group of muscles in your shoulder, swell and rub against your acromion.
- Subacromial bursitis: a condition in which small fluid-filled sacs, called bursas, swell within your shoulder joints, causing pain and infection.
Indications of scapular dyskinesis include symptoms such as:
- Pain or tenderness surrounding the scapula
- Weakness in the arm or shoulder of that scapula
- Fatigue while performing repetitive activities, especially overhead activities
- Crunching or snapping sounds that accompany shoulder movement
- Drooping posture on the side of the affected scapula
- Limited range of motion
- A protrusion or winged look for the affected scapula
Your doctor may be able to diagnose scapular dyskinesis with an exam. This exam may include visual observation and muscle testing. In some cases, imaging such as an X-ray or MRI may be required to determine the source of scapular dyskinesis.
Treatment for scapular dyskinesis will depend on the severity of your condition and what is causing your condition.
Nonsteroidal anti-inflammatory drugs, commonly called NSAIDs, can help you reduce swelling. Examples of NSAIDs include ibuprofen (Advil) and naproxen (Aleve).
Physical therapy can also help with scapular dyskinesis. Physical therapy can strengthen the muscles that move and stabilize the scapula and can stretch these muscles if they’re tight.
Occasionally, though, surgery may be required to repair injured muscle and tissue.
If you’re concerned that you may have sustained an injury to the scapula or one of the attached muscles, schedule an appointment with your doctor right away to avoid causing more damage.