The different bursae
The bursa at the elbow (bursa olecrani) is present to protect the structures there (bones, tendons, ligaments and adjacent tissue). It is located in the so-called subcutaneous tissue between the skin and the bone and ensures that the skin can move relative to the underlying bone. The fluid it contains compensates for shocks.
It serves as a sliding layer between the structures. Since the elbow is a highly stressed joint and can be subjected to great pressure or impact, the bursa is of great importance. If the bursa is heavily loaded, for example when the elbow is supported on a table, an inflammation can occur (bursitis).
This inflammation, which is triggered by constant strain, is also known as “student elbow”. Besides inflammation, injuries to the bursa are not uncommon due to the exposed position. The bursa at the hip (bursa trochanterica) lies between the thigh bone and the tendons running above it.
There are three different types of bursa trochanterica. They are located at the side of the hip between the thigh bone and three different tendons of gluteal muscles. Further bursae are located in the depth of the hip near the hip joint between the muscles there.
There is also another bursa between the skin and the bone. The exact location of the bursae of the hip is not known with certainty. Since the hip is a highly stressed joint and can be subject to great pressure, these bursae are important for compensating for impacts.
The bursa under the tendons is important for padding and protecting the structures, since otherwise the tendons would rest directly on the bone. This would lead to frictional damage during movement. As with the elbow, the bursae of the hip can also be affected by inflammation.
There are several bursa sacs at the knee. There is a large bursa between the skin and the kneecap (bursa praepatellaris). It is flat and belongs to the skin bursa.
It is responsible for the displacement of the skin in relation to the patella when the knee is bent. Since it lies very superficially, it can be injured quickly. During work involving kneeling for a long period of time, for example for tilers or cleaning staff, the permanent strain can cause the bursa to become inflamed.
Another large bursa (bursa suprapatellaris) is located above the knee joint. It is located between the thigh bone and the tendon of the anterior thigh muscle. It is responsible for the smooth sliding of the tendon over the bone when bending the knee.
In addition, the bursa evenly distributes pressures that arise in this area. There is a connection between this bursa and the joint cavity of the knee, which is why it is also called the “Recessus suprapatellaris”. Below the knee joint there is another bursa (bursa infrapatellaris).
It is divided into two parts. The superficial part lies between the skin and the patellar tendon. The deep part is located between the patellar tendon and the underlying bone.
Like the other bursae, this two-part bursa is important for the frictionless gliding of the tendon over the bone. Bursae of the knee can become chronically inflamed as a result of constant stress in a kneeling position, for example at work. Other smaller bursae are located in the hollow of the knee.
The bursa at the Achilles tendon is divided in two. The superficial part is distinguished from the deep part. The superficial part is located between the skin and the tendon and the deep part is located between the Achilles tendon and the underlying bone.
Depending on the foot position, the pressure on the bursa can be increased or decreased. The bursa with the fluid it contains is responsible for the even distribution of the pressure and the friction-free sliding of the tendon and the bone.The bursa can be chronically inflamed and very painful. If this is the case, it should be removed surgically.
An inflammation of the bursa can be promoted by a foot malposition. There are several bursa sacs on the shoulder. One bursa is located between the so-called shoulder corner joint and the tendon of a shoulder muscle (bursa subacromialis).
It is responsible for ensuring that the humerus does not touch the bony roof of the shoulder when the arm is raised. It is also important for the mobility of the tendon relative to the bone. The tendon of the muscle can change degeneratively, which can lead to inflammatory processes of the bursa.
The bursa may become sticky, so that it can no longer fulfil its function. Other bursa sacs are located under the tendons of the shoulder muscles. Together, the bursa sacs ensure the smooth gliding of the muscles or their tendons over the bones when the arm is lifted.
When working with the arms above the head, the risk of inflammation of these bursae is increased. Examples are chopping wood or painting. Inflammation can also occur during sports where the arm is raised frequently.
