Joint Structure and Function Lecture Flashcards
What basic biological materials form periarticular connective tissue?
- Fibrillar components
- Collagen
- Elastin
- Interfibrillar components
- Glycosaminoglycans, water, solutes
- Determines tissue’s function
- Cells
- Fibroblasts and chondrocytes
Explain what fibrillar components are.
- Main substance of most connective tissue
- Have high tensile strength
- Type I
- tissue tensile strength
- Binds and supports bony articulations
- Type II
- Maintain shape and consistency
What is the function and structure of fibrocartilage?
- Is comprised of mostly type I collagen
- Provides stability and support
- Helps guide movement and dissipate forces
- They do not have pain sensory fibers (some near insertions to bone)
- Limited blood supply
What is the structure and function of hyaline articular cartilage?
- Primarily type II collagen
- Relatively thin, but complex and highly ordered
- Covers the ends of long bones in synovial joints
- Provides smooth low friction surfaces
- Helps dissipate stress to the underlying bone
- Little to no vascular or nerve supply
What are some characteristics of elastin?
- Have more give when stretched
- Readily return to their original shape after being deformed
- Found in all joint structures
What are the 2 layers of bones?
- Cortical
- Cancellous
What is the periosteum?
This is the fibrous layer that covers non-articular surface of bone and houses cells that are needed for growth and repair
What is the microstructure of the trabecular bone?
- It is arranged in parallel layers
- Arranged in lines corresponding to where max stress is applied to the body
- Compressive loading will cause hypertrophy
What is tensile loading of a bone?
a load that pulls the bone apart causing elongation
What is compressive loading of a bone?
a load that pushed the bone together causing shortening
What is torsional loading of a bone?
Twisting load
What is shear loading of a bone?
Loading that causes surfaces to try and slide past each other
What is bending of a bone?
Tensile load on convex side and compressive load on the concave side
What are some properties of tendons?
- 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)
What are some properties of ligaments?
- 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
What is stress?
the internal resistance generate as the structure resists deformation divided by its cross-sectional area
S=F/A
What is strain?
Percent increase in a tissue’s stretched length relative to its original length
Strain = (L2- L1)/ L1
In reference to the stress-strain curve, what occurs in the toe region?
Slack is taken out of the tissue
In reference to the stress-strain curve, what is the elastic region?
This is the area right after the toe region that refers to ta materials stiffness
In reference to the stress-strain curve, what occurs at the yield point?
This is the region after the elastic region that indicates the start of the plastic region.
In reference to the stress-strain curve, what occurs in plastic region?
Permanent deformation after the load is removed and progressive failure as stress continues
At which portion of the stress-strain curve is a clinical assessment of ligament status conducted?
Toe region
At which portion of the stress-strain curve results in the deformation that occurs during normal play?
Elastic region
At which portion of the stress-strain curve results in a grade 1 ligament sprain with injury to a few fibers?
Plastic Region
At which portion of the stress-strain curve results in a grade 2 ligament sprain and partial tear?
Plastic region but further up the curve
At which portion of the stress-strain curve results in a grade 3 ligament sprain/ complete rupture?
Point C, macrofailure
What is viscoelasticity/creep?
A progressive strain of a material under a constant load over time
What are some features of diarthroses joints?
They ALWAYS have
- Joint capsule
- Joint cavity that is enclosed by a joint capsule
- Synovial tissue that lines the capsule
- Synovial fluid that forms a film over the joint surfaces
- Hyaline cartilage that covers the surfaces of the bones
What are the diarthrodial uniaxial types?
- Hinge
- Pivot
What are the diarthrodial biaxial types?
- Condyloid joint
- Saddle joint
What are the diarthrodial multiaxial types?
- Plane Joint
- Ball and socket joint
What are the general changes as a result of immobilization?
- Joint capsule shrinks and becomes tighter
- Muscles become shorter with less force production
- Decrease collagen content in ligaments and tendons
- Cartilage on articular surfaces and bones will atropy
- Bone osteoporosis or osteopenia can occur