Shoulder Joint

What is a shoulder joint?

A joint is a place where the ends of two bones make contact with each other to allow motion. Your shoulder is made up of two joints that connect the three bones of your shoulder together with soft tissue, muscle, tendons, ligaments and cartilage.

The three bones in your shoulder are your:

• Shoulder blade (scapula).
• Collarbone (clavicle).
• Upper arm bone (humerus).

Because of the motion of these three bones at your shoulder joint, the arm can be moved to position the elbow and hand.

What two joints make up the shoulder joint?

The two joints that make up your shoulder joint are:

• The acromioclavicular joint: The acromioclavicular joint joins the top of your shoulder blade (acromion) and your collarbone together.
• The glenohumeral joint: The glenohumeral joint joins the rounded top of your upper arm bone into your shoulder blade (glenoid cavity of the scapula).

What type of joint is the shoulder?

The shoulder joint is a ball-and-socket joint (spheroidal joint). This is a joint where a rounded bone moves inside the curved surface of another bone.

You can mimic this joint by making your right hand into a fist and placing your fist into the palm of your left hand. Cup the fingers of your left hand over your right fist. When you move your right forearm up and down or side to side while keeping your right fist pressed against your left palm, that’s the range of motion of a ball and socket joint. Because of the coordinated movements of the two joints of the shoulder and the movement of the scapula over the rib cage, the shoulder has the greatest range of motion of any joint in your body.

What does a shoulder joint do?

Your shoulder joint allows you to move your arm. It connects the three bones in your shoulder. This gives you a wide range of motion. Your shoulder joint lets you complete tasks with your arm like reaching for items on a tall shelf or throwing a ball.

How does the shoulder joint work?

The bones of your shoulder are supported by the following components that help you move your arm:

• Ligaments and tendons: Ligaments and tendons are fibrous and flexible materials that connect bones to bones and bone to muscle. These components hold and support your shoulder joint.
• Cartilage: Cartilage is a flexible material that covers your bones where they meet at the joint. It allows your bones to move against each other (articular cartilage), steadies your movement (labrum) and absorbs shock like the soles of your sneakers.
• Muscles: A muscle called your rotator cuff sits between your shoulder blade and your upper arm bone. This muscle helps support and stabilize your joint by hugging it.
• Bursa: Your muscles, ligaments and tendons move freely because of a bursa. This is a fluid-filled sac within your joint that provides cushioning.
• Synovial membrane: The synovial membrane is a sticky fluid that surrounds your joint to lubricate it and facilitate movement.

Where is the shoulder joint located?

Your shoulder joints are located at the top of your arm. They connect your arms to your torso. Your acromioclavicular joint connects your collarbone and your shoulder blade. Below your acromioclavicular joint is your glenohumeral joint that connects your upper arm bone and your shoulder blade.

The human body has two shoulder joints, one on each side of the body at the top of each arm, connecting the arms to the torso.

What does the shoulder joint look like?

You have two joints in your shoulder. Each one looks different:

• The acromioclavicular joint: The acromioclavicular joint connects your shoulder blade and collarbone. It looks similar to two pencils placed one after another in a single, straight line. There’s a small gap in between each pencil.
• The glenohumeral joint: The glenohumeral joint connects your upper arm to your shoulder blade. Your shoulder blade is curved like a cup. It holds your upper arm bone, which is long and straight with a rounded end. The rounded end of your arm bone fits into the cup of your shoulder blade to make a joint.

What are the common conditions that affect the shoulder joint?

You move your shoulder joints often. This can lead to common injuries or wear and tear that include:

• Joint sprain: A ligament in your shoulder joint that overstretches or tears.
• Dislocated shoulder: The ball (humeral head) separates from the glenoid cavity of the scapula.
• Arthritis: Pain and inflammation of your joints.
• Bursitis: The fluid-filled sac in your joint swells up.
• Tendinitis: Inflammation of the tendons in your shoulder.
• Shoulder fracture: A break in one of your shoulder bones that connect at the joint.

What are the signs or symptoms of shoulder joint conditions?

The most common symptoms that affect your shoulder joints include:

• Pain.
• Swelling.
• Stiff muscles.
• Skin discoloration or bruising.
• Limited movement, pain with movement or not being able to use your arm as you normally do.

What tests check the health of my shoulder joints?

A healthcare provider may offer an imaging test to get a better look at your shoulder joints. The most common type of imaging tests are an X-ray or an MRI. These will help your provider look at the bones, muscles, tendons and ligaments in your shoulder joint.

How are common shoulder joint conditions treated?

Treatment can vary based on what caused your shoulder joint injury or condition. Common treatments may include:

• Wearing a sling until your joint fracture heals.
• Surgery to repair the components of your shoulder joint.
• Physical therapy to help you improve motion and build strength.
• Taking medications to reduce inflammation or pain.
• Resting and limiting the use of your arm until your joint heals completely.

A healthcare provider will let you know what type of treatment is best for your diagnosis.

How do I keep my shoulder joints healthy?

You can keep your shoulder joints healthy by:

• Eating a healthy diet.
• Stretching before you exercise.
• Participating in regular activities, light exercise or exercise recommended by your healthcare provider.
• Protecting your body from physical injury by wearing personal equipment when playing contact sports.

A note from Cleveland Clinic

Your shoulder joints provide your arms with a wide range of motion. They’re the most flexible part of your body. Without these joints, you’ll have limited use of your arms. You can keep your shoulder joints healthy by eating a well-balanced diet and stretching and exercising as your healthcare provider recommends.