Synovial Membrane

The synovial membrane is a thin barrier that lines the inside of some of your joints. You might also see it referred to as your synovium.

Your synovial membranes encase your joints in a layer of synovial fluid. The fluid protects your joints and helps them move smoothly.

These membranes are part of your musculoskeletal system that help you sit, stand and move.

What does the synovial membrane do?

Your synovial membranes protect the joints they surround. They form what’s called a synovial capsule around your joints. They work with your cartilage, tendons and ligaments to reduce friction between the bones in your joints. This is especially true when you move a joint.

How the synovium works depends on which kind of joint it’s protecting.

For example, the membrane in your elbow lubricates your joint as you bend and straighten your arm. It prevents the ends of your upper arm bone and the bones in your lower arm (your radius and ulna) from rubbing together.

The membrane in your hip reduces friction between the rounded head of your thigh bone and the socket in your pelvis that it fits into.

Where are they located?

A synovium protects any of your joints where two bones move together, including your:

• Shoulders
• Elbows
• Wrists
• Fingers, thumbs and knuckles
• Hips
• Knees
• Ankles
• Feet

What are the parts of the synovial membrane?

Synovial membranes vary in size. It depends on which joint they’re in. But in general, they’re small. They’re usually less than a third of an inch (around 1 centimeter) thick.

A synovium has two layers:

• The inner layer (intima): The thin inner layer makes the synovial fluid that lubricates your joints.
• The outer layer (subintimal): The outer layer is made of tough, fiber-like cells. It protects the inner layer. It contains nerve cells, lymphatic cells and blood vessels.

What are the common conditions and disorders that affect the synovial membrane?

Lots of conditions and injuries that affect your joints can damage your synovium, too. Arthritis is the most common issue that will affect your synovial membranes and the joints they protect. Forms of arthritis that commonly affect these membranes include:

• Osteoarthritis
• Rheumatoid arthritis
• Gout

Other conditions can affect your synovial membranes, including:

• Repetitive strain injuries
• Bursitis
• Synovitis
• Synovial sarcomas

Signs/symptoms something isn’t working right

Visit a healthcare provider if you notice any changes or symptoms in your joints, including:

• Swelling
• Pain that doesn’t get better in a few days
• Tenderness
• Difficulty moving a part of your body like you usually can
• Discoloration or bruising

Keeping your synovium healthy

Anything you do to maintain your overall health will benefit your synovial membranes and joints. Follow a healthy eating plan and get plenty of physical activity.

You can lower your chances of developing arthritis by:

• Not using tobacco products
• Doing low-impact, non-weight-bearing exercise
• Maintaining a weight that’s healthy for you

Follow these general safety tips to reduce your risk of an injury to your joints:

• Always wear your seatbelt.
• Wear the right protective equipment for all activities and sports.
• Make sure your home and workspace are free of clutter that could trip you or others.
• Always use the proper tools or equipment at home to reach things. Never stand on chairs, tables or countertops.
• Use your cane or walker if you have difficulty walking or have an increased risk of falls.