Arthrology: Contemporary Classification - Diarthrosis, Common Features

Question 1

What are the synonyms for synovial (diarthrosis) joints?

Answer 1

junctura synovalis or synovial joint

Question 2

What are the four consistent features of synovial (diarthrosis) joints?

Answer 2

articular or fibrous capsule, synovial membrane, articular cartilage, and synovial fluid

Question 3

Thickening of the fibrous capsule connective tissue will form the what?

Answer 3

capsular ligament

Question 4

What generic accessory ligaments may accompany and support the capsular ligament?

Answer 4

intracapsular and extracapsular ligaments

Question 5

What are examples of intracapsular and extracapsular ligaments?

Answer 5

intracapsular ligaments - cruciate ligaments of the knee; extracapsular ligaments - collateral ligaments of the knee

Question 6

What is the generic function of ligaments?

Answer 6

stimulate reflex contraction of muscles around the joint

Question 7

What are the characteristics of the type I articular receptors?

Answer 7

located in the superficial layer of the fibrous capsule, resemble Ruffini endings, most numerous in cervical zygapophyses, and they monitor the joint “at rest”

Question 8

What are the characteristics of type II articular receptors?

Answer 8

located in deeper strata of the fibrous capsule, resemble Pacinian corpuscles, most numerous in the cervical spine, and monitor the joint during normal range of motion

Question 9

What are the characteristics of type III articular receptors?

Answer 9

present in collateral and intrinsic ligaments, resemble Golgi tendon organs, not initially observed along the vertebral column, and monitor extreme joint motion

Question 10

What is the function of type IV articular receptors?

Answer 10

nociceptive, they monitor pain

Question 11

Type IVa articular receptors would be present in what locations?

Answer 11

fibrous capsule, articular fat pads, or adventitia of blood vessels

Question 12

Type IVb articular receptors would be present in what location?

Answer 12

accessory ligaments in general, dense in the posterior longitudinal ligament of the spine

Question 13

Type IV articular receptors would be absent in what part(s) of the synovial (diarthrosis) joint?

Answer 13

synovial membrane, articular cartilage, and synovial menisci or intra-articular discs

Question 14

What are the three classifications of synovial membrane?

Answer 14

articular, vaginal, and bursal synovial membrane

Question 15

What are the three modifications of articular synovial membrane?

Answer 15

1) synovial villi, 2) articular fat pads or Haversian glands, 3) synovial menisci and intra-articular discs

Question 16

What is the generic function of modifications of articular synovial membrane?

Answer 16

aid in spreading synovial fluid

Question 17

What is the name given to the finger-like extensions of the synovial membrane? What is their apparent function?

Answer 17

synovial villi; increase the surface of synovial membrane available for secretion-absorption phenomena

Question 18

What role will aging have in synovial villi number?

Answer 18

synovial villi increase with age

Question 19

What is another name for the articular fat pad? Where are they located?

Answer 19

Haversian gland; in the fibrous layer of synovial membrane; they are absent from articular cartilage, synovial menisci, and intra-articular disc

Question 20

Articular fat pads are most numerous in what location along the vertebral column?

Answer 20

lumbar zygapophyses

Question 21

Condensed fibrous connective tissue or fibrocartilage projections of the synovial membrane are called what?

Answer 21

synovial menisci or intra-articular discs

Question 22

Intra-articular discs are a feature of what joint examples?

Answer 22

temporomandibular, sternoclavicular, acromioclavicular, and radio-ulnar joints

Question 23

Synovial menisci are a feature of what joint examples?

Answer 23

femur-tibia articulation, cervical zygapophyses and lumbar zygapophyses

Question 24

What are the layers of the synovial membrane?

Answer 24

outer fibrous layer and an inner (lumenal) cellular layer AKA synovial lamina intima

Question 25

What are the specific functions of type A synovial cells?

Answer 25

are phagocytic

Question 26

What are the specific functions of type B synovial cells?

Answer 26

secrete proteinaceous substances and hyaluronic acid

Question 27

What is the common function of type A and B synovial cells?

Answer 27

formation and absorption of synovial fluid

Question 28

How does the articular cartilage thickness vary within the joint?

Answer 28

male (convex) surfaces on bone are thicker at the center of the articular region; female (concave) surfaces on bone are thicker at the periphery of the articular region

Question 29

What is the source of nutrition for articular cartilage?

Answer 29

blood vessels in the synovial membrane, sinuses of the bone marrow cavity, and from synovial fluid itself

Question 30

What is unique about the surface of articular cartilage?

Answer 30

a true perichondrium is absent

Question 31

What are the primary constituents of articular cartilage?

Answer 31

water, cells, collagen type II fibers, and a proteoglycan gel

Question 32

Which collagen fiber type predominates in articular cartilage?

Answer 32

type II

Question 33

What are proteoglycans composed of?

Answer 33

a core protein and glycosaminoglycans

Question 34

What are glycosaminoglycans?

Answer 34

relatively long, non-branched carbohydrates formed from repeating units of disaccharides

Question 35

What are examples of glycosaminoglycans important in articular cartilage?

Answer 35

hyaluronic acid, chondroitin sulfates, and keratin sulfates

Question 36

What is the architecture of the largest proteoglycans?

Answer 36

a backbone of hyaluronic acid to which core proteins are bound, chondroitin sulfates and keratin sulfates are then bound to the core protein

Question 37

What is the primary function of bound glycosaminoglycans in articular cartilage?

Answer 37

form a network for water retention

Question 38

Cartilage is able to change shape due to compression, a characteristic known as what?

Answer 38

deformation

Question 39

What is implied when cartilage is said to have elastic properties?

Answer 39

cartilage can deform and returns to original volume rapidly, a time independent property

Question 40

What is implied when cartilage is said to have viscoelastic properties?

Answer 40

cartilage can deform but returns to original volume slowly, a time dependent property

Question 41

Which theory of joint lubrication implies a loss of fluid from the cartilage into the joint space during compression results in increased viscosity of the synovial fluid?

Answer 41

weeping theory

Question 42

Which theory of joint lubrication implies water loss from the synovial fluid increases viscosity of the remaining synovial fluid?

Answer 42

boosted theory

Question 43

Which theory of joint lubrication implies and adsorption of lubricant onto cartilage surfaces is responsible for the low-friction observed during movement?

Answer 43

boundary theory

Question 44

What are the properties of synovial fluid?

Answer 44

it is yellow-white, viscous, slightly alkaline, and tastes salty

Question 45

Synovial fluid consists of what specific chemical groups?

Answer 45

fats, salts, albumins, and hyaluronate

Question 46

Which sustance in synovial fluid was first thought to be responsible for its viscosity and lubricating behavior?

Answer 46

hyaluronate

Question 47

What substance of synovial fluid has been proposed to be responsible for its viscosity and lubricating behavior?

Answer 47

lubricin

Question 48

What cells are often observed in synovial fluid?

Answer 48

white blood cells and a few other types of connective tissue cells

Question 49

What is the function of synovial fluid?

Answer 49

provides a nutritive source for articular cartilage and supply the lubricant for the cartilage surface