Bursae of the shoulder.
Four bursae related to the front of the knee joint. Note that the suprapatellar bursa communicates with the cavity of the joint.
A bursa is a fluid-filled pad that acts as a cushion and a lubricating device at a pressure point in the body – often near a joint, where tendons rub against bones, ligaments, or other tendons. Bursae are commonly found close to joints where the skin rubs against underlying bony structures. Important bursae are those associated with the knee, elbow, and shoulder.
Occasionally, the cavity of a bursa communicates with the cavity of a synovial joint. For example, the suprapatellar bursa communicates with the knee joint, and the subscaularis bursa communicates with the shoulder joint.
Disorders of bursae
Inflammation of a bursa is called bursitis and can be extremely painful. A bursitis may be visible as a red and tender
swelling on the surface, as at the elbow, or it may be hidden in deeper
layers such as within the buttock, groin, or hip. Treatment involves reducing
the swelling and prevention of further inflammation.
A bunion is a thickened bursa at the base of the big toe.