1. Prepared by I Gede Purnawinadi, S.Kep., M.Kes.
Joints
Prepared by I Gede Purnawinadi, S.Kep., M.Kes.

2. Classification of Joints
Joints are the weakest parts of the skeleton. Nonetheless, their structure resists various forces, such as crushing or tearing, that threaten to force them out of alignment.
Joints are classified by structure and by function.
The structural classification focuses on the material binding the bones together and whether or not a joint cavity is present.
Structurally, there are fibrous, cartilaginous, and synovial joints

3. The functional classification is based on the amount of movement allowed at the joint.
On this basis, there are synarthroses (sin″ar-thro′sēz; syn = together, arthro = joint), which are immovable joints;
amphiarthroses (am″fe-ar-thro′seēz; amphi = on both sides), slightly movable joints; and
diarthroses (di″ar-thro′sēz; dia = through, apart), or freely movable joints.
Freely movable joints predominate in the limbs; immovable and slightly movable joints are largely restricted to the axial skeleton.

4. Fibrous Joints
In fibrous joints, the bones are joined by fibrous tissue; no joint cavity is present.
The amount of movement allowed depends on the length of the connective tissue fibers uniting the bones. Although a few are slightly movable, most fibrous joints are immovable.
The three types of fibrous joints are sutures, syndesmoses, and gomphoses.

5. Sutures, literally “seams,” occur only between bones of the skull
Sutures, literally “seams,” occur only between bones of the skull. The wavy articulating bone edges interlock, and the junction is completely filled by a minimal amount of very short connective tissue fibers that are continuous with the periosteum.
In syndesmoses (sin″des-mo′sēz), the bones are connected by a ligament (syndesmos = ligament), a cord or band of fibrous tissue. Although the connecting fibers are always longer than those in sutures, they vary quite a bit in length.
A gomphosis (gom-fo′sis) is a peg-in-socket fibrous joint. The only example is the articulation of a tooth with its bony alveolar socket. The term gomphosis comes from the Greek gompho, meaning “nail” or “bolt,” and refers to the way teeth are embedded in their sockets (as if hammered in). The fibrous connection in this case is the short periodontal ligament

7. Cartilaginous Joints
In cartilaginous joints (kar″ti-laj′ĭ-nus), the articulating bones are united by cartilage. Like fibrous joints, they lack a joint cavity.
The two types of cartilaginous joints are synchondroses and symphyses.
A bar or plate of hyaline cartilage unites the bones at a synchondrosis (sin″kon-dro′sis; “junction of cartilage”). Virtually all synchondroses are synarthrotic.
In symphyses (sim′fih-sēz; “growing together”) the articular surfaces of the bones are covered with articular (hyaline) cartilage, which in turn is fused to an intervening pad, or plate, of fibrocartilage.

8. Cartilaginous joints.  
The epiphyseal plate in a growing long bone is a temporary synchondrosis; the shaft and epiphysis are connected by hyaline cartilage that is later completely ossified.
(b) The sternocostal joint between rib 1 and the manubrium of the sternum is an immovable hyaline cartilage joint, or synchondrosis.
(c) The intervertebral joints, in which the vertebrae are connected by fibrocartilaginous discs, are symphyses.

9. Synovial Joints
Synovial joints are those in which the articulating bones are separated by a fluid-containing joint cavity. This arrangement permits substantial freedom of movement, and all synovial joints are freely movable diarthroses. All joints of the limbs—indeed, most joints of the body—fall into this class.
Although all synovial joints have structural features in common, they do not have a common structural plan. Based on the shape of their articular surfaces, which in turn determine the movements allowed, synovial joints can be classified further into six major categories— plane, hinge, pivot, condyloid, saddle, and ball-and-socket joints.

11. Range of motion allowed by synovial joints varies from nonaxial movement (slipping movements only, since there is no axis around which movement can occur) to uniaxial movement (movement in one plane) to biaxial movement (movement in two planes) to multiaxial movement (movement in or around all three planes of space and axes).

13. Movements Allowed by Synovial Joints
There are three general types of movements:
gliding,
angular movements, and
rotation.

17. Homeostatic Imbalances of Joints
Few of us pay attention to our joints unless something goes wrong with them.
Joint pain and malfunction can be caused by a number of factors, but most joint problems result from injuries and inflammatory or degenerative conditions.

18. Common Joint Injuries Sprains
In a sprain, the ligaments reinforcing a joint are stretched or torn. The lumbar region of the spine, the ankle, and the knee are common sprain sites.
Cartilage Injuries
Cartilage injuries involve tearing of the knee menisci, overuse damage to the articular cartilages of other joints is becoming increasingly common in competitive young athletes.
Dislocations
A occurs when bones are forced out of alignment. It is usually accompaniedislocation (luxation) d by sprains, inflammation, and joint immobilization.

23. Inflammatory and Degenerative Conditions
Inflammatory conditions that affect joints include bursitis, tendonitis, and various forms of arthritis.
Bursitis is inflammation of a bursa and is usually caused by a blow or friction.
Tendonitis is inflammation of tendon sheaths, typically caused by overuse. Its symptoms (pain and swelling) and treatment (rest, ice, and anti-inflammatory drugs).
The term arthritis describes over 100 different types of inflammatory or degenerative diseases that damage the joints.