The result can be in pain in one place, as in tennis elbow or frozen shoulder, or more general pain, as in fibromyalgia. A joint is where one bone moves against another. Where two bones meet, a layer of smooth cartilage coats the bone surfaces, stopping them grinding against one another. A tough layer of tissue surrounds the area, forming what is known as a capsule. Strong elastic ligaments hold the bones and capsule firmly in place.
Muscles expand and contract to make the joint move.
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