Shoulder Joint Structure, Muscles, And How To Treat Effusion | Glenohumeral Joint

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The shoulder joint, or glenohumeral joint, is one of the largest and most complex joints in the human body. It takes a “ball and socket” form joining the upper arm, the humerus, and the glenoid socket of the shoulder blade or scapula. Synovial fluid cushions the connection to prevent friction. When there is an injury, fluid builds up and effusion occurs. We discuss the causes, diagnosis, and treatment in depth below.
RELATED: Rotator Cuff Tear Symptoms To Watch Out For
In this article:

  1. What Are the Important Structures of the Shoulder Joint?
  2. What Are the Most Common Shoulder Injuries?
  3. What Are the Symptoms of Glenohumeral Joint Effusion?
  4. Why Does Glenohumeral Joint Effusion Occur?
  5. Who Is at Risk of Getting Glenohumeral Joint Effusion?
  6. When Should One See a Doctor?
  7. Where Should One Go for Glenohumeral Joint Diagnosis?
  8. What Are the Treatments for Glenohumeral Joint Effusion?

Shoulder Joint, Muscles, and How to Treat Glenohumeral Joint Effusion

What Are the Important Structures of the Shoulder Joint?

Articulating Surfaces

The glenohumeral joint joins the upper arm, humerus, and glenoid socket of the shoulder blade or scapula to form the articular surfaces.

Joint Capsule and the Bursae

A fibrous sheath called the joint capsule encloses the structures of the glenohumeral joint. This extends from the neck of the humerus to the rim of the glenoid cavity.
The joint capsule is lined with the synovial membrane, which produces synovial fluid that reduces the friction between the connection.
Sac-like structures called synovial bursae contain the synovial fluid. The two most important bursae are:

  1. Subacromial Bursa – Located under the deltoid and acromion, this bursa reduces the friction underneath the deltoid allowing free motion of the rotator cuff.
  2. Subscapular Bursa – Located between the scapula and the subscapularis tendon, this bursa reduces tendon wear and tear during shoulder joint movements.


Ligaments are connective tissues that stabilize the glenohumeral joint when moving. Five of the most important shoulder joint ligaments are:

  1. Glenohumeral Ligaments – This group of ligaments forms the joint capsule and connects the proximal humerus (upper arm) to the glenoid cavity. These are the main stabilizers of the shoulders.
  2. Coracohumeral Ligament – This ligament connects the base of the coracoid process, a small hook-like structure on the lateral edge of the upper front portion of the shoulder blade, to the proximal humerus.
  3. Transverse Humeral Ligament – This ligament stretches between the two tubercles (the rounded part) of the humerus.
  4. Coracoclavicular Ligament – This ligament is made up of the conoid and trapezoid ligaments and stretches from the collarbone to the scapular coracoid process.
  5. Acromioclavicular Ligament – This ligament, together with the coracoclavicular ligament, keeps the acromioclavicular joint (collarbone) aligned to the shoulder blade.


The largest among shoulder muscles is the deltoid. It’s a huge triangle-shaped muscle covering the glenohumeral joint and shaping the shoulder.
It runs across the top of the shoulder from the collarbone in front of the posterior scapula. It’s crucial in preventing joint dislocation when carrying heavy objects.
Other shoulder muscles include:

  • Triceps Brachii – This is the large muscle found in the back of the upper arm. It helps in straightening the arm.
  • Infraspinatus – This is a rotator cuff muscle helping in the lowering and raising of the upper arm.
  • Pectoralis Major – The pectoralis major muscle is a fan-shaped muscle running from the armpit to the clavicle and down across the lower chest area. It joins to the breastbone or sternum.
  • Pectoralis Minor – This is smaller than the pectoralis major. It runs from the upper ribs up to the total shoulder.
  • Teres Major – This muscle is involved with upper arm rotation.
  • Latissimus Dorsi – This is a flat triangular muscle found in the back. It helps with arm lateral rotation and in moving the arm away and closer to the body.
  • Serratus Anterior – This works to pull the shoulder forward to the rib cage.

What Are the Most Common Shoulder Injuries?

Like other joints in the body, the shoulder joint may also be injured. Here are its common injuries:

  • Adhesive Capsulitis – This is a painful and debilitating condition of unclear cause characterized by inflammation and stiffness of the shoulder joint capsule.
  • Shoulder Subluxation – This is a partial dislocation of the glenohumeral joint usually caused by changes in the joint’s mechanical integrity.
  • Rotator Cuff Tear – This is the wear and tear of the rotator cuff resulting in a dull ache in the shoulder which tends to worsen when sleeping on one’s side.
  • Shoulder Bursitis – This is the inflammation of the bursae in the shoulder.
  • Glenohumeral Joint Effusion – This is the accumulation of fluid in the shoulder joint. It may be caused by arthritis or injury of the ligaments in the shoulder joint.

What Are the Symptoms of Glenohumeral Joint Effusion?

Below are the symptoms of glenohumeral joint effusion. The occurrence may vary depending on the cause.

  • Bruising (if caused by an injury)
  • Swelling
  • Warmth in the affected area
  • Stiffness
  • Unbearable pain when standing or walking

RELATED: The Different Types Of Joints In The Body

Why Does Glenohumeral Joint Effusion Occur?

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Causes of glenohumeral joint effusion:

  • Shoulder strain
  • Repetitive sports injury
  • Torn ligaments or cartilage
  • Bacterial infection within the joint
  • Bone fracture
  • Gout
  • Rheumatoid Arthritis
  • Osteoarthritis

Who Is at Risk of Getting Glenohumeral Joint Effusion?

Everyone is at risk of getting shoulder joint effusion but some are more at risk than others:

  • Older people – Risk increases with age.
  • Athletes – Strenuous training can cause fluid buildup in the joints.
  • People who are overweight – Excess weight puts more stress on the joints.
  • People with arthritis

Many sports that have ‘cut-and-run’ maneuvers increase the risk of joint effusion. Examples of these are football, soccer, and tennis.

When Should One See a Doctor?

Regular joint pain and swelling subside after resting and applying ice to the affected area. A few other home remedies for joint effusion, such as a warm bath or a massage, can also be tried.
When a serious injury is sustained and non-medicinal remedies don’t work, it is time to see the doctor. Ache or inflammation that lasts for days indicates a serious injury.
In severe cases, the joints cannot bend or move without extreme discomfort.

Where Should One Go for Glenohumeral Joint Diagnosis?

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Prior to treatment, the doctor will examine the patient’s medical history. Previous knee or joint conditions, like arthritis, will be duly noted.
The doctor will, then, perform a physical exam on the affected joints, testing the range of motion. If the diagnosis is unclear, the doctor may request diagnostic exams.
Diagnostic Tests for Glenohumeral Joint Effusion

  • Synovial Fluid Analysis. A medical professional will extract fluid from the joint and test it for crystals, infection-causing bacteria, protein, and glucose. A positive result may indicate gout. The lab will also test the fluid for blood cells that may indicate injury to the joint.
  • Blood Chemistry. Doctors may draw blood from the patient to check for levels of inflammation and the presence of antibodies or infection.
  • Imaging Tests. X-ray, ultrasound, CT scan, or MRI read the structural changes and erosions in the joint, the location and amount of fluid, cartilage loss, and presence of loose tissue fragments.

What Are the Treatments for Glenohumeral Joint Effusion?

The type of treatment will rely on diagnosis results. Depending on the injury and severity, it ranges from physical therapy to oral medication to invasive treatment procedures:

  • Antibiotics to fight infection
  • Anti-inflammatories like corticosteroids injections to reduce swelling
  • Analgesics to relieve discomfort
  • Joint aspiration to drain fluid from the joint in order to relieve pressure resulting from excess fluid
  • Physical therapy to improve flexibility and strength of the supporting muscles
  • Surgical repair, i.e. total shoulder replacement
  • Supporting health supplements for a speedy recovery

Rheumatologists may treat the joint ailment with medication or physical therapy. If surgery is necessary, the expertise of an orthopedic surgeon is crucial.
The patient can also consult a sports medicine specialist. They specialize in the prevention, evaluation, and treatment of injuries related to sports and exercise.
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Anyone who regularly subjects their joints to stress runs the risk of acquiring joint effusion. Maintain joint health by keeping a healthy lifestyle to avoid joint injury.
Listen to the body and consult a doctor when necessary.
Have you experienced joint effusion? How did you manage your ailment? Share your experience in the comments section below!
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This post was originally published on August 27, 2018, and has been updated for quality and relevancy.

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