This section is from the book "Health", by W. H. Coefield.
Bones are joined together in several ways. In the first place, they are joined together by what we call fixed or immovable joints, such as have been explained in our description of the skull. Then there are mixed joints, which are neither fixed nor very movable, such as we have explained in the vertebral column, and the joints between the collar-bones and breast-bone.
Further, there are what are called true joints or movable joints, which are constructed as follows:- Two pieces of bone would rub together harshly, so the ends are covered with a softer substance-gristle or cartilage-and between the cartilage of each bone there is placed a little bag of membrane, closed on all sides, which is capable of secreting fluid in its inside-that fluid is called synovia, and the bag itself, the synovial membrane. There is no way into this bag and no way out of it, and it is placed in between the ends of the two bones, and so keeps the joint continually moist and soft.
Besides that, there are structures passing from bone to bone which bind them together, and because they bind are called ligaments. They are made of a tough substance, called fibrous tissue; it is the white, shiny substance often met with in a joint of meat; sometimes there are so many of these ligaments as to surround the whole joint,-for instance, in the hip-joint,-when they are called the capsule of the joint.