Library · Disease
Bursitis
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Bursitis is inflammation of a bursa. A bursa is a small sac lined on the inside with synovium, the same slippery membrane found inside joints, and its job is to cushion: it sits where bone, muscle, tendon and ligament rub against each other.
When everything is fine, that sac takes up almost no space: it is collapsed on itself, flattened. If something irritates it, it fills with synovial fluid and swells. It is a deflated pouch between two parts that rub; full of fluid, it no longer fits where it used to. That is why it hurts: any movement against it or any pressure from above squeezes it.
What irritates it most is sustained pressure, when the bursa gets pinched between a hard surface and a bony prominence. Next comes a direct blow to the bursa.
In brief
Bursitis is swelling or inflammation of a bursa, a synovium-lined sac that provides cushioning between bone, muscle, tendon and ligament.
The bursa is a potential space collapsed on itself; a stimulus irritates it, it fills with synovial fluid, and then any pressure on it hurts.
It is a deflated pouch between two parts that rub; full of fluid, it no longer fits where it used to.
The most common cause is prolonged pressure between a hard surface and a bony prominence; the second is direct trauma.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingBursitis, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
Updated