Basic Human Anatomy

3-13. BURSA

3-13. BURSA

a. A bursa (figure 3-3) is the simplest of serous cavities. Each bursa is a small sac located between two moving structures, usually a muscle moving over a bony surface. The bursa reduces the friction between the two structures. For example, a bursa prevents excessive friction between the skin and patella (knee cap). This bursa, called the prepatellar bursa, allows the skin to move freely over the patella. (When injured, it produces excessive amounts of the serous fluid and is known as "housemaid's knee.")

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b. As a fibrous sac, each bursa has a central cavity which is lined with a serous membrane. This membrane is a simple squamous epithelium. The serous membrane secretes a serous fluid into the serous cavity. The serous fluid is the lubricant, minimizing friction.

Primary Content Providers: The U. S. Army, The U.S. Navy
Ancillary Content and Online Version: David L. Heiserman
Publisher: SweetHaven Publishing Services