physiology of joints

Question 1

what are the 3 types of joints

Answer 1

synovial
fibrous
cartilaginous

Question 2

what are features of fibrous joint (synarthrosis)

Answer 2

• bones united by fibrous tissue
• doesn’t allow any movement
• examples are the bones in the skull of adults

Question 3

what are features of cartilaginous joints

Answer 3

• bones united by cartilage
• allow limited movement
• eg. invertebral discs

Question 4

what are features of the synovial joints (diarthrosis)

Answer 4

• bones separated by a cavity and united by a fibrous capsule
• the inner aspect of fibrous capsule is lined with synovial membrane
• synovial membrane is vascular connective tissue
• synovial membrane contains synovial cells that produces synovial fluid

Question 5

what are functions of the synovial fluid

Answer 5

• lubricates joints
• facilitates joint movements - reduces friction
• helps minimise wear and tear of joints through efficient lubrication
• aids the nutrition of articular cartilage
• supplies the chondrocytes with O2 and nutrients and removes CO2 and waste products

Question 6

what are general characteristics of synovial fluid

Answer 6

• fills the joint cavity
• continually replenished and absorbed by the synovial membrane
• high viscosity mainly due to the presence of hyaluronic acid (mucin) produced by synovial cells
• viscosity of the synovial fluid varies with joint movement

Question 7

in regards to viscosity and elasticity what is rapid movement associated with

Answer 7

• decreased viscosity

- increased elasticity

Question 8

what are viscosity for
normal synovial fluid:
inflammatory synovial fluid:
septic synovial fluid:

Answer 8

normal synovial fluid: high
inflammatory synovial fluid:low
septic synovial fluid:variable

Question 9

what is the colour of
normal synovial fluid:
inflammatory synovial fluid:
septic synovial fluid:

Answer 9

normal synovial fluid: clear
inflammatory synovial fluid:straw to yellow
septic synovial fluid:variable

Question 10

what I step clarity of
normal synovial fluid:
inflammatory synovial fluid:
septic synovial fluid:

Answer 10

normal synovial fluid:transparent
inflammatory synovial fluid:transparent
septic synovial fluid:opaque

Question 11

what is the total white cell count for
normal synovial fluid:
inflammatory synovial fluid:
septic synovial fluid:

Answer 11

normal synovial fluid: <200
inflammatory synovial fluid: 2000-75000
septic synovial fluid: >100000

Question 12

what are the main functions of articular cartilage

Answer 12

• provide a low friction lubricated gliding surface - help prevent wear and tear
• distributes contact pressure to subchondral bone
• composition of the cartilage extracellular matrix and the interaction between the fluid and solid phase of the cartilage plays a significant role in determining the mechanical properties of cartilage

Question 13

what are the main components of cartilage

Answer 13

water
collagen
proteoglycan

Question 14

what are features of an osteoarthritic knee

Answer 14

• thickened capsule
• cyst formation
• sclerosis in subchondral bone
• fibrillated cartilage
• synovial hypertrophy
• osteocyte formation