Joints, Synovial Fluids and Cartilage

Question 1

Which joints are fibrous joints

Answer 1

Peridontal Ligament, the cranial sutures and the interosseous membranes

Question 2

Describe a fibrous joint

Answer 2

At a fibrous joint, the adjacent bones are directly connected to each other by fibrous connective tissue, and thus the bones do not have a joint cavity between them

Question 3

State the three types of fibrous joints

Answer 3

Sutures, Gomphoses and Syndesmoses

Question 4

Sutures

Answer 4

Immovable joints only found between, the flat plate like bones of the skull

Question 5

When are suture joints important

Answer 5

At birth

Question 6

Gomphoses

Answer 6

Immovable joint where the teeth articulate with their sockets in the maxillae or the mandible

Question 7

Syndesmosis

Answer 7

Movable joints in which bones are held together by an interosseus membrane

Question 8

What are the function of syndesmosis joints

Answer 8

Provide strength along the length of long bones

Question 9

Give examples of syndesmosis joints

Answer 9

Middle radio-ulnar and the middle tibiofibular joints

Question 10

In cartilaginous joints, what are the bones attached by

Answer 10

Fibro or hyaline cartilage

Question 11

What type of cartilage do synchondroses or primary cartilaginous joints contain

Answer 11

Hyaline

Question 12

Give an example of a primary cartilaginous joint

Answer 12

Between the diaphysis and epiphysis

Question 13

symphyses

Answer 13

Involve either hyaline or fibrocartilage and are slightly movable. An example is the pubic symphysis

Question 14

Hinge synovial joint

Answer 14

Permits flexion and extension. Elbow joint is an example

Question 15

Saddle synovial joint

Answer 15

Concave and convex joint surfaces unite at saddle joints. An example is the metatarsophalangeal joint

Question 16

Plane synovial joint

Answer 16

Permits gliding or sliding movements. Example is the acromioclavicular joint

Question 17

Pivot synovial joint

Answer 17

Allows rotation; a round bony process fits into a bony ligamentous socket. Examples are the atlantoaxial joint and the proximal radio-ulnar joint

Question 18

Condyloid synovial joint

Answer 18

Permits flexion, extension, adduction, abduction and circumduction. Metacarpophalangeal joint (middle of the hand)

Question 19

Ball and socket synovial joint

Answer 19

Permits movement in several axis, an example is the glenohumeral joint

Question 20

The articular cartilage of synovial joints is made up of

Answer 20

Hyaline cartilage

Question 21

Describe the superficial/tangential layer of cartilage

Answer 21

Made up of flattened chondrocytes that produce collagen and glycoproteins (lubricin)

Question 22

Describe the transitional layer of cartilage

Answer 22

Round chondrocytes that produce proteoglycans from superifical to deep levels

Question 23

State the main functions of cartilage

Answer 23

Supporting the framework of organs, form the articulating surfaces of bones and growth and development of long bones

Question 24

Which cartilage is the weakest

Answer 24

Hyaline cartilage

Question 25

Describe the collagen fibres in hyaline cartilage

Answer 25

Widely dispersed thin type 2

Question 26

Strongest type of cartilage

Answer 26

Fibrocartilage

Question 27

Describe the structure of fibrocartilage

Answer 27

alternating layers of hyaline cartilage matrix and thick layers of dense collagen fibres orientated in the direction of functional stresses

Question 28

Describe the structure of elastic cartilage

Answer 28

The chondrocytes are found in a threadlike network of elastic fibres in the matrix

Question 29

What are the constituents of cartilage

Answer 29

Chondroblasts, chondrocytes and extracellular matrix (10% aggrecan, 75% water and a mix of collagen fibres)

Question 30

State the function of chondroblasts

Answer 30

Secrete matrix and fibres into the ECM of cartilage

Question 31

What are chondrocytes

Answer 31

Trapped chondroblasts which have matured into chondrocytes

Question 32

What are lacunae

Answer 32

Matrix encolsed comparments that chondrocytes sit in

Question 33

The surface of most cartilage is covered by

Answer 33

A layer of dense irregular connective tissue called the perichondrium

Question 34

What does the outer layer of the periochondrium contain

Answer 34

Collagen producing fibroblasts

Question 35

What does the inner layer of the perichondrium contain

Answer 35

Chondroblasts

Question 36

What is the vascularity of cartilage

Answer 36

Avascular

Question 37

How does cartilage get nourished

Answer 37

Long range diffusion from nearby capillaries in the perichondrium

Question 38

Interstitial growth of cartilage

Answer 38

Chondrocytes grow and divide and lay down more matrix inside existing cartilage

Question 39

Appositional growth of cartilage

Answer 39

New surface layers of matrix are added to the pre-existing matrix by new chondroblasts from the perichondrium

Question 40

How is articular cartilage nourished

Answer 40

From the synovial fluid produced by the synovial membrane

Question 41

What cells produce synovial fluid

Answer 41

Synoviocytes

Question 42

Type A synoviocytes

Answer 42

Look like macrophages. These remove debris and contribute to fluid production.

Question 43

Type B synoviocytes

Answer 43

Fibroblast-like and main producer of synovial fluid

Question 44

What is synovial fluid made up of

Answer 44

• Viscous fluid
• Hyaluronic acid and lubricin, collagenases and proteinases
• Fluid component

Question 45

State the functions of synovial fluid

Answer 45

Nutrition of articular cartilage, removal of waste products and lubrication

Question 46

Describe the process of lubrication

Answer 46

boundary including glycoproteins such as lubricin bind to receptors on articular surfaces to form a thin film. It is hydrodynamic – surfaces kept apart by liquid pressure and viscosity changes with load and velocity of movements

Question 47

What happens to the viscosity of synovial fluid as age increases

Answer 47

Increases, slower joint movements and reduced lubrication

Question 48

What happens to the water content of cartilage as age increases

Answer 48

Decreases - therefore reduced shock absorption