Joint Structure and Function

Question 0

What is mechanotherapy?

Answer 0

The clinical application of mechanotransduction - where therapeutic exercise is prescribed to promote repair and remodeling of injured tissue

Question 1

What does Wolfe’s Law explain?

Answer 1

Structure follows function

Question 2

What are some types of connective tissue involved with joint structures?

Answer 2

Bones, bursae, capsules, cartilage, discs, fat pads, menisci, ligaments, and tendons

Question 3

What is the extracellular matrix?

Answer 3

Part outside of the cell

Question 5

Why are cells and the extracellular matrix important?

Answer 5

Determine the function of a joint - when the cells are squeezed, they are stimulated to produce more collagen

Question 6

What are two types of deformation and what do they cause?

Answer 6

Tensile load (pulling) - causes elongation
Compression load (pushing) - causes compression

Question 7

What is stress?

Answer 7

Force per unit area - affected by how big something is

Question 8

What is strain?

Answer 8

Elongation per unit length in response to tensile load

Question 9

What are the three types of forces?

Answer 9

Tension, compression, and shear force

Question 10

What is the correlation between length and thickness with regards to force?

Answer 10

If fibers that are the same length, the object with more fibers (thickness) will need more force in order for them to be the same length

Question 11

What is the correlation between elongation and length with regards to strain?

Answer 11

An object with a longer length will have a longer elongation when compared to an object with a shorter length but the same amount as strain

Question 12

What is the total failure percentage in a stress-strain curve?

Answer 12

8%

Question 13

What does Young’s Modulus of elasticity explain?

Answer 13

A tendon that is damaged can be stretched the same length with a lot less force

Question 14

What is viscoelasticity?

Answer 14

The combination of elasticity and vicosity

Question 15

What is viscosity?

Answer 15

Resistance to flow

Question 16

What is the importance of the speed of movement of flow?

Answer 16

When you want to stretch something, if you do it slower, then you will be able to do it longer

Question 17

What is creep?

Answer 17

Force applied is the same over time and the deformation increases - object will slowly start to sink down

Question 18

What is the stress-relaxation relationship?

Answer 18

Is tissue is stretched to a fixed length over time, the force required to keep that length would decrease

Question 19

What is hysteresis?

Answer 19

The loading and unloading does not follow the same path due to energy lost as heat (ex: rubber band wearing out from constant push and pull)

Question 20

What is the strain-rate sensitivity correlation?

Answer 20

When load is applied rapidly, the tissue is stiffer - stretch slowly

Question 21

What does a tendon attach?

Answer 21

Muscle to bone

Question 22

What does a ligament attach?

Answer 22

Bone to bone

Question 23

What determines the tendon/ligament properties and what do they provide?

Answer 23

Elastin - provides elasticity

Collagen - provides strength

Question 24

What is entheses?

Answer 24

Tendon and ligament attachment to the bone - indirectly via fibrous attachment and directly via fibrocartilage

Question 25

Which is more elastic, ligaments or tendons?

Answer 25

Tendons

Question 26

What is the relationship between tendons and ligaments and force?

Answer 26

Tendons and ligaments become stiffer with increased rate of force application

Question 27

What are the two ways the tendon load can be increased?

Answer 27

Increase the external load (gravity) or increase the speed of movement

Question 28

How does hopping affect the tendon load?

Answer 28

Increases the tendon load by 5x the body weight

Question 29

How does temperature affect tendons and ligaments?

Answer 29

Increased temperature will decrease the stiffness, increase creep and relaxation, and decrease tissue failure limit

Question 30

How does aging affect tendons and ligaments?

Answer 30

Tensile strength increases during childhood and you have maximal tensile strength at skeletal maturity (gradually declines during adulthood)

Question 31

What is the SAID principle?

Answer 31

Specific adaptation to imposed demand

Question 32

What is the effect of immobilization?

Answer 32

Decreases tensile strength and stiffness and causes contractures - can be minimized if tendon/ligament is elongated

Question 33

What is the effect of exercise on tendons and ligaments?

Answer 33

Increases circulation and can minimize loss of strength associated with aging or injury

Question 34

What is the function of a bursae?

Answer 34

Shock absorption and protection from compression

Question 35

What is the hardest form of connective tissue?

Answer 35

Bone

Question 36

What are the main functions of bones?

Answer 36

Serve as framework for body, serve as levers for muscle action, and protect viscera

Question 37

Is bone static or dynamic tissue?

Answer 37

Dynamic

Question 38

What are the three types of bone structures?

Answer 38

Cancellous bone - soft, inner layer Cortical bone - hard, outer layer Growth plates

Question 39

What is the percentage of turnover in cancellous bone and cortical bone per year?

Answer 39

Cancellous - 25% Cortical - 3% -Higher turnover with cancellous bone because it is more fragile and has a different vascular station

Question 40

Why is the compression on a bone more than body weight?

Answer 40

Compression is both body weight and muscle force

Question 41

What are the two bending forces on bone when standing?

Answer 41

Compression - medially | Tension - laterally

Question 42

What is anisotropy?

Answer 42

Bone has different mechanical properties in different directions

Question 43

What is the relationship between density and activity with regards to bone?

Answer 43

Increased activity --> increased density | Decreased activity --> decreased density

Question 44

What is the function of cartilage?

Answer 44

Distribute joint loads over as large an area as possible and allow contact and movement between two bony surfaces with minimal friction and wear

Question 45

What is cartilage mostly composed of?

Answer 45

Water

Question 46

What is the importance of glycosaminoglycans (GAG) in cartilage function?

Answer 46

Contains molecules that imbibe water which swells the tissue and gives it stiffness (helps disperse repetitive forces) and allows for nutrient delivery

Question 47

What are three types of cartilage?

Answer 47

Hyaline - low friction Fibrocartilage - high friction - found in joints Elastic cartilage

Question 48

Is joint cartilage avascular or vascular?

Answer 48

Avascular

Question 49

How is cartilaginous compressibility affected by the rate of loading?

Answer 49

Rapid loading causes the cartilage to become stiffer

Question 50

What happens to the fluid content of cartilage when subjected to a constant load?

Answer 50

Undergoes creep

Question 51

How are compression of cartilage and shear forces related in creating cartilage failure?

Answer 51

Compression causes shear forces at cartilage-bone interface (shear stressed occur when liquid goes out the sides)

Question 52

What are some mechanical factors that can cause osteoarthritis?

Answer 52

Obesity, repetitive loading, joint instability, and rapid loading

Question 53

What is the relationship between exercise and cartilage?

Answer 53

High loading sports can cause increased osteoarthritis, ROM exercises cause increased fluid flow in and out of cartilage and moderate exercise causes an increase in gag count which increases tensile strength

Question 54

What are two categories of joints?

Answer 54

1. Diarthroses - synovial joints that allow free movement | 2. Synarthroses - nonsynovial joints

Question 55

What are two types of synarthroses joints?

Answer 55

1. Fibrous joints - sutures, gomphoses, and syndesmoses | 2. Cartilaginous joints - symphyses and synchondrosis

Question 56

What are the two layers of the joint capsule?

Answer 56

Stratum fibrosum - outside, poor vascularization, rich innervation Stratum synovium - inside, rich vascularization, poor innervation

Question 57

What is the function of the stratum fibrosum and stratum synovium?

Answer 57

Stratum fibrosum - position and movement sense | Stratum synovium - produces synovial fluid

Question 58

What are the three classifications of diarthrodial joints?

Answer 58

1. Uniaxial - hinge and pivot joints 2. Biaxial - condyloid and saddle joints 3. Triaxial - plane and ball and socket joints

Question 59

What is hypermobility and hypomobility?

Answer 59

Hypermobility - ROM exceeds normal | Hypomobility - ROM less than normal

Question 60

What is osteokinetmatics?

Answer 60

Refers to the rotary movements of the ones in space during physiological joint motion

Question 61

What is arthrokinetmatics?

Answer 61

Accessory motion - motion of the joint surfaces in relation to another

Question 62

What are the three terms used in arthrokinematics?

Answer 62

Roll, glide, and spin

Question 63

What is the convex on cave rule?

Answer 63

Roll and glide occur in opposite directions

Question 64

What is the concave on convex rule?

Answer 64

Roll and glide occur in same direction

Question 65

What is a closed-pack position?

Answer 65

Joint surfaces have maximal congruency and the ligaments and capsule are taut

Question 66

What are the two parts of the extracellular matrix?

Answer 66

Fibrillar component - collagen and elastin | Interfibrillar component - water