joints, synovial fluid and cartillage

Question 1

What are the 3 types of joints

Answer 1

fibrous, synovial and cartilaginous

Question 2

Describe the structure of fibrous joints

Answer 2

2 bones connected by fibrous connective tissue which is densely packed collagen which makes the joint very rigid

Question 3

Describe the structure of cartilaginous joint

Answer 3

2 bones connected by cartilage

Question 4

What type of joint has the most movement

Answer 4

synovial joint

Question 5

What are examples of fibrous joints

Answer 5

cranial sutures and interosseous membranes

Question 6

Where are interosseous membranes

Answer 6

In between radius and ulna

In between tibia and fibula

Question 7

What kind of cartilage is in primary cartilaginous joints

Answer 7

Hyaline

Question 8

What kind of cartilage is in a secondary cartilaginous joint

Answer 8

Hyaline and fibrocartilage

Question 9

Where are primary cartilaginous joints seen

Answer 9

In the epiphyseal growth plate of long bones

Question 10

What is an example of secondary cartilaginous joints

Answer 10

Intervertebral discs - made of fibrocartilage but with hyaline cartilage on both sides of the vertebrae which is in contact with the intervertebral disc

Question 11

What is another name for primary cartilaginous joint

Answer 11

Synchondrosis

Question 12

What is another name for a secondary cartilaginous joint

Answer 12

Symphysis

Question 13

What are common features of a synovial joint

Answer 13

Synovial capsule surrounded by a fibrous capsule made of collagen fibres and a synovial cavity within the capsule lined by synovial membrane which produces synovial fluid

Question 14

What lines the bones in a synovial joint so that the bones don’t rub directly against each other

Answer 14

Articulate cartilage (hyaline)

Question 15

Why is the shoulder joint incrogruent (not a good fit)

Answer 15

The glenoid cavity is quite deep while the humeral head is very round so they do not match up great - this makes the joint quite unstable although there is high movement

Question 16

What prevents dislocation of the shoulder joint

Answer 16

Fibrous capsule and ligaments which provide stability
The rotator cuff muscles also stabilise the joint

Question 17

What are the attributes of articular cartilage

Answer 17

High water content, impermeable and strong under compression

Question 18

What makes hyaline cartilage hydrophilic

Answer 18

Presence of glycosaminoglycans in them which are highly polar and therefore attract water into the cartilage

Question 19

What is the thickness of articular cartilage on average

Answer 19

2-3 mm

Question 20

Does cartilage have blood, lymphatic or neural supply

Answer 20

No, cartilage is avascular, aneural and alymphatic

Question 21

What is the name of the synovial fluid

Answer 21

Synovium

Question 22

What cells in the synovial membrane produces synovium

Answer 22

Synoviocytes

Question 23

What is required for the synoviocytes to produce synovium efficiently

Answer 23

A rich capillary network and no epithelial lining which allows for direct exchange of nutrients such as O2, CO2 and metabolites between blood and synovial fluid

Question 24

What is the function of type A synoviocytes

Answer 24

Removing of debris from the synovial cavity and contribute to the production of synovial fluid

Question 25

What is the function of type B synoviocytes

Answer 25

Main producer of synovial fluid

Question 26

What are the properties of synovial fluid

Answer 26

It is quite viscous
Hyaluranic acid and lubricin are found in the synovial fluid
The fluid component of the synovial fluid comes from the plasma

Question 27

Why is synovial fluid used as a lubricant

Answer 27

Reduces friction in the joint and therefore there is less wear

Question 28

What is fluid film lubrication

Answer 28

The two surfaces are kept completely apart by a layer of fluid

Question 29

What is weeping lubrication

Answer 29

Some of the interstitial fluid is squeezed out of the cartilage into the synovial cavity to increase the fluid volume

Question 30

What is the boundary lubrication

Answer 30

There is contact between surfaces but the surfaces are coated in bio lubricants like lipids, hyaluronic acid and lubricin

Question 31

What are bursae and what is their function

Answer 31

Fluid filled sacs e.g supra-patellar bursa - they cushion the joint

Question 32

What are fat pads and what do they do

Answer 32

They are filled with adipocytes and help lubricate the joints

Question 33

What is the effect of ageing on cartilage

Answer 33

Thinning of articular cartilage
Water content of cartilage decreases
The quantity of molecules such as hyaluronic acid which affects the viscosity change
Summary effect - increased stiffness, brittleness, reduced shock absorption and less protection of articular surfaces and increased risk of damage