Joint Structure and Function Lecture

Question 1

What basic biological materials form periarticular connective tissue?

Answer 1

1. Fibrillar components
   
   1. Collagen
   2. Elastin
2. Interfibrillar components
   
   1. Glycosaminoglycans, water, solutes
   2. Determines tissue’s function
3. Cells
   
   1. Fibroblasts and chondrocytes

Question 2

Explain what fibrillar components are.

Answer 2

1. Main substance of most connective tissue
2. Have high tensile strength
3. Type I
   
   1. tissue tensile strength
   2. Binds and supports bony articulations
4. Type II
   
   1. Maintain shape and consistency

Question 3

What is the function and structure of fibrocartilage?

Answer 3

1. Is comprised of mostly type I collagen
2. Provides stability and support
3. Helps guide movement and dissipate forces
4. They do not have pain sensory fibers (some near insertions to bone)
5. Limited blood supply

Question 4

What is the structure and function of hyaline articular cartilage?

Answer 4

1. Primarily type II collagen
2. Relatively thin, but complex and highly ordered
3. Covers the ends of long bones in synovial joints
4. Provides smooth low friction surfaces
5. Helps dissipate stress to the underlying bone
6. Little to no vascular or nerve supply

Question 5

What are some characteristics of elastin?

Answer 5

1. Have more give when stretched
2. Readily return to their original shape after being deformed
3. Found in all joint structures

Question 6

What are the 2 layers of bones?

Answer 6

1. Cortical
2. Cancellous

Question 7

What is the periosteum?

Answer 7

This is the fibrous layer that covers non-articular surface of bone and houses cells that are needed for growth and repair

Question 8

What is the microstructure of the trabecular bone?

Answer 8

• It is arranged in parallel layers
• Arranged in lines corresponding to where max stress is applied to the body
• Compressive loading will cause hypertrophy

Question 9

What is tensile loading of a bone?

Answer 9

a load that pulls the bone apart causing elongation

Question 10

What is compressive loading of a bone?

Answer 10

a load that pushed the bone together causing shortening

Question 11

What is torsional loading of a bone?

Answer 11

Twisting load

Question 12

What is shear loading of a bone?

Answer 12

Loading that causes surfaces to try and slide past each other

Question 13

What is bending of a bone?

Answer 13

Tensile load on convex side and compressive load on the concave side

Question 14

What are some properties of tendons?

Answer 14

• Collagen fibers are nearly parallel
• CSA, composition, and length determine the amount of force that can be resisted
• Tendons undergo adaptations through increasing thickness and strength overtime (they get stronger with force/load applied)

Question 15

What are some properties of ligaments?

Answer 15

• Similar to tendons mechanically
• Fiber bundles are arranged in line with applied tensile forces
• are oriented in more directions than tendon so they can handle loads in different directions without being damaged
• similar to tendons, adapt to stress applied

Question 16

What is stress?

Answer 16

the internal resistance generate as the structure resists deformation divided by its cross-sectional area

S=F/A

Question 17

What is strain?

Answer 17

Percent increase in a tissue’s stretched length relative to its original length

Strain = (L2- L1)/ L1

Question 18

In reference to the stress-strain curve, what occurs in the toe region?

Answer 18

Slack is taken out of the tissue

Question 19

In reference to the stress-strain curve, what is the elastic region?

Answer 19

This is the area right after the toe region that refers to ta materials stiffness

Question 20

In reference to the stress-strain curve, what occurs at the yield point?

Answer 20

This is the region after the elastic region that indicates the start of the plastic region.

Question 21

In reference to the stress-strain curve, what occurs in plastic region?

Answer 21

Permanent deformation after the load is removed and progressive failure as stress continues

Question 22

At which portion of the stress-strain curve is a clinical assessment of ligament status conducted?

Answer 22

Toe region

Question 23

At which portion of the stress-strain curve results in the deformation that occurs during normal play?

Answer 23

Elastic region

Question 24

At which portion of the stress-strain curve results in a grade 1 ligament sprain with injury to a few fibers?

Answer 24

Plastic Region

Question 25

At which portion of the stress-strain curve results in a grade 2 ligament sprain and partial tear?

Answer 25

Plastic region but further up the curve

Question 26

At which portion of the stress-strain curve results in a grade 3 ligament sprain/ complete rupture?

Answer 26

Point C, macrofailure

Question 27

What is viscoelasticity/creep?

Answer 27

A progressive strain of a material under a constant load over time

Question 28

What are some features of diarthroses joints?

Answer 28

They ALWAYS have

1. Joint capsule
2. Joint cavity that is enclosed by a joint capsule
3. Synovial tissue that lines the capsule
4. Synovial fluid that forms a film over the joint surfaces
5. Hyaline cartilage that covers the surfaces of the bones

Question 29

What are the diarthrodial uniaxial types?

Answer 29

1. Hinge
2. Pivot

Question 30

What are the diarthrodial biaxial types?

Answer 30

1. Condyloid joint
2. Saddle joint

Question 31

What are the diarthrodial multiaxial types?

Answer 31

1. Plane Joint
2. Ball and socket joint

Question 32

What are the general changes as a result of immobilization?

Answer 32

1. Joint capsule shrinks and becomes tighter
2. Muscles become shorter with less force production
3. Decrease collagen content in ligaments and tendons
4. Cartilage on articular surfaces and bones will atropy
5. Bone osteoporosis or osteopenia can occur