The Anatomy of the Bursae

Small Fluid-Filled Sacs That Allow Your Joints to Move Smoothly

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Bursae are small sacs of fluid within a joint. The body has approximately 150 bursae, and they each provide cushioning and lubrication to protect the joints as they move. 

A bursa (singular of bursae) can become inflamed, causing pain and discomfort. Bursitis, which is inflammation of the bursa, can usually be treated with rest, ice, and anti-inflammatory medication. Prevention involves avoiding overuse, especially if you have already had bursitis in a certain joint.

Anatomy 

Bursae are lined with a type of tissue called synovium, and the fluid inside each bursa is described as synovial fluid. These small sacs are found in synovial joints throughout your body.

Each of your synovial joints is a complex structure that is held together by several types of connective tissue. Joints contain bones, cartilage, ligaments, tendons, muscles, and several bursae.

Structure 

Each bursa is a few centimeters in size, but they do vary in size and are not all identical. The bursae are soft, are able to tolerate reasonable movement, and can be squeezed within a joint (within limits, of course) without becoming damaged. 

Each of your bursa fits into its location between bone and adjoining tissue. While the lining of a bursa is resilient enough to endure sliding motion, it stays in place.

Location 

Your bursae are located in between the moving structures of your synovial joints. Some of these sacs are found deep within a joint, such as between a bone and a tendon or ligament, and some are near the surface, between your skin and a bone. 

Your bursa can be found in the following structures: 

  • Shoulders
  • Hips
  • Elbows 
  • Knees 
  • Wrists
  • Ankles
  • Fingers 
  • Toes

Function

Bursae provide a surface that prevents pain, abrasion, or damage of skin, bones, muscles, ligaments, and tendons as they move within a joint. These small pockets, with their relatively smooth surface and lubricating fluid, allow the moving parts of a joint to slide smoothly against each other and against the bursa.

Associated Conditions

There are a few different conditions that can affect the bursa. These conditions are common and typically do not cause serious problems.

Bursae can become swollen, inflamed, infected, or injured. These conditions may cause pain and tenderness, but you can have a small swelling or even a hardening of the bursa (such as a bunion) without experiencing any pain or discomfort.

Small Growths

The bursa in the regions of your elbows, toes, or hands can become somewhat tough as a result of recurrent pressure. This may develop as a way to protect the skin and bony tissue.

These areas, like bunions or “Popeye elbow” can be visible, may feel hard to the touch, and can become a little darker than the nearby skin.

These small growths usually don’t cause substantial pain or discomfort and they usually can soften after the pressure discontinues.

Bursitis

Inflammation of the bursa can occur due to overuse of a joint. For example, sports, repetitive physical work, or pressure due to something like ill-fitting shoes, can cause bursitis. 

Arthritis, an example of bursitis, is inflammation of the synovial lining and other joint structures. Arthritis can occur as the result of wear and tear (osteoarthritis) or as a result of an autoimmune disease (rheumatoid arthritis).

Infection

An infection, septic bursitis, can occur in the synovial lining, the synovial fluid, or both. Septic bursitis can produce warmth and pain of the bursa. A major injury can predispose you to an infection. 

Injury

A traumatic injury can damage one or more of the bursa in a joint, potentially causing bleeding and swelling. 

Rehabilitation

Often, bursitis can improve with conservative measures, such as ice, rest, or physical therapy. In some instances, having a wrapping placed around your joint may help reduce pain and swelling as the inflammation decreases.

Sometimes, taking anti-inflammatory treatment, such as over-the-counter (OTC) non-steroidal anti-inflammatory medications (NSAIDs) can reduce the inflammation. Examples of OTC NSAIDs include Aleve (naproxen) and Advil (ibuprofen). Steroids or prescription NSAIDs such as Celebrex (celecoxib), Voltaren (diclofenac) may be suitable for persistent bursitis.

For infection of the bursa, antibiotics are often necessary. 

Often, bursitis is treated with a combination of approaches, such as therapy, rest and medication.

If you have a major injury, you may need a surgical procedure to repair your joint or to remove excess fluid or blood. Generally, you should expect to have physical therapy after recovery from surgery, and you may need to learn how to adjust your physical activity to avoid triggering a flare-up of bursitis.

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