Ch. 9 Joints

Question 1

Define a joint (articulation)

Answer 1

Joints or articulations are sites were two or more bones meet

Question 2

Describe the function of joints

Answer 2

Joints have two fundamental functions:
1. Give skeleton mobility.
2. Hold skeleton together.

Question 3

Describe the three functional classifications of joints and give an example

Answer 3

1. SYNARTHROSES - immovable joints * Cranial sutures
2. AMPHIARTHROSES. - slightly movable * Vertebrae
3. DIARTHROSES - freely moveable joints * Hip joint

Question 4

Name the fibrous joints that are classified by structure

Answer 4

1. Fiber joints - Sutures
2. Cartilaginous - Syndesmoses
3. Synovial joints - Gomphoses

Question 5

Describe how fibrous joint are classified by structure

Answer 5

In fibrous joints, the bones are joined by dense fibers, connective tissue, and no joint cavity is present

Most synarthrotic (immovable) - The amount of movement depends on length of connective tissue fibers

Three types
1. Sutures - occur only between the bones of the skull, immovable, interlocking joints for protection of brain, short, connective tissue fibers - cranial sutures
2. Syndesmoses - bones are connected only by ligaments, fiber length varies - movement varies - little to no movement, (Inferiotibiofibular joint) large amount of movement (at interosseous membrane) connecting radius and ulna
3. Gomphoses - the only gomphoses are the peg-in-socket joints of teeth in aveolar sockets, fibrous connection is the periodontal ligament

Question 6

Describe how cartilaginous joints are classified by structure

Answer 6

In cartilaginous joints, the bones are joined by cartilage, like fiberous joints they have no joint cavity, not highly movable

Two types - synchondroses and symphesis

Synchondroses - a bar or plate of hyaline cartilage unite bones - almost all are synarthrotic (no movement) - temporary epiphyseal plate joints (become synostoses after plate closure) - cartilage of first rib with manubrium

Question 7

Describe how synovial junctions are classified by structure

Answer 7

Are the joints in which the articular bones are separated by fluid filled joint cavity, all are diarthrotic (freely moving), nearly all joints of the limbs, and most joints of body are synovial joints - knee joint

Question 8

Describe the six distinguishing characteristics of synovial joints

Answer 8

1. Hyaline cartilage covers the opposing bone surfaces as articular cartilage (absorb compression and prevent crushing of bone ends)
2. Joint (synovial) cavity - small, fluid-filled space
3. The joint cavity is enclosed by a two layered articular (joint) capsule
   external fibrous layer (dense, irregular connective tissue) inner synovial membrane (loose connective tissue, makes synovial fluid)
4. Synovial fluid occupies free space within the joint capsule - slippery filtrate of plasma, lubricates, and nourishes articular cartilage, contains phagocytic cells to remove microbes and debris
5. Synovial joints are reinforced by different types of reinforcing ligaments (may be found as part of the fibrous layer outside the capsule or deep in the capsule)
6. Richly supplied with nerves and blood vessels - nerve fibers detect pain, monitor joint position and stretch, capillary beds supply filtrate for missing synovial fluid

Question 9

Identify the features of a synovial joint including : bone, ligament, joint cavity, synovial fluid, joint (articular) capsule (fibrous layer, synovial membrane), articular cartilage

Answer 9

Question 10

Describe (in a general sense ) other features of synovial joints, including fat pads, articular discs (menisci)birthday and tendon sheaths

Answer 10

Fat pads - questioning between fibrous layer and synovial membrane or bone
Articular disc (menisci) -fibrocartliage separates articular surfaces to improve fit of bone and stabilize joint and reduce wear and tear.
Bursae - sax lined with synovial membrane (contains synovial fluid), reduce friction where ligaments, muscles, skin, tendons, or bones rub together
Tendon sheaths - elongated bursa wrapped completely around tendon subjected to friction

Question 11

Explain how he synovial joints stability is maintained

Answer 11

Joints are constantly stretched and compressed. They must be stabilized if they did not dislocate. The ability of his joint depends on three factors:
1. Shapes of articular surfaces (minor role) non-complementary articulating surface vs. ball and socket
2. Ligament number and location (limited role) the more ligaments, the stronger it is
3. Muscle tone keeps these tendons taught - extremely important and reinforcing shoulder and knee joints and arches of the foot