Exam 1 Prep Flashcards
Biomechanics
The use of the laws of physics to describe motion of the body and its forces
What makes up a synovial joint?
-Ends of bones
-Cartilage
-Menisci
-Ligaments
-Tendons
-Joint capsule
-Synovium
-Muscle & tendon
What does synovial fluid do?
Lowers the coefficient of friction in the joint and prevents wear and tear
What are the functions of muscles?
-Statically: to stabilize isometric contractions
-Dynamic: to move (concentric and eccentric contractions)
What are the four basic types of body tissues?
-Thelial
-Nerve
-Muscle
-Connective
What are the 5 basic types of connective tissue?
-Blood
-Fat
-Bone
-Cartilage
-Ordinary (ligaments, tendons, fascia, neural coverings)
What are the 3 components of all connective tissues?
-Cells (blasts, cytes)
-Extracellular matrix (proteoglycans)
-Fibers (collagen, elastin)
What is the role of proteoglycans in connective tissue?
They imbibe water and resist compression
What are the properties of collagen?
Collagen is more stiff and resists tension
What are the properties of elastin?
Elastin has more give than collagen, but it still resists tension
What connective tissues have the best order with individual fibers?
Tendons & ligaments
What is the most abundant protein in the body?
Collagen
In what specific joint in the body are there a lot of proteoglycans found?
There are a lot of proteoglycans found in intervertebral discs because they need to resist compression to protect the spine. There are also high concentrations in synovial fluid.
What are the properties of bone?
-Bone needs to resist stress in all directions
-It contains collagen fibers and inorganic salts
Cartilage
Needs to resist compression
What is the connective tissues response to lack of stress?
-Leads to loss of strength in the connective tissue
-Loss of proteoglycans
-Irregular pattern of collagen cross linking
What is the weakest type of tissue in the body?
Connective tissue is the weakest link
What are the 3 different body planes?
-Frontal
-Sagittal
-Transverse
What movements occur in the frontal plane?
Abduction and adduction
What movements occur in the sagittal plane?
Flexion and extension
What movements occur in the transverse plane?
Rotation
Kinematics
the set of concepts that allows us to describe displacement or motion without thinking about the forces that cause the movement
Kinetics
The study of the forces that are causing the movement
One degree of freedom
The freedom to move through one plane
What are the two types of motion?
-Linear
-Angular (rotatory)
Osteokinematics
physiologic motions (i.e. flexion/extension)
Arthrokinematics
understanding the movement occurring at the joint surfaces
Loose pack position
-Structures are most lax
-Greatest amount of joint play
-Usually at midranges
Close pack position
-Usually at end ranges
-Structures surrounding the joint are taught
-Most stable position
Describe the arthrokinematics of a concave bone surface rotating on a convex bone surface
The concave surface is rotating upwards and gliding upwards in the same direction
Closed kinematic chain
When two ends are fixed
Open kinematic chain
One end of the chain is moving, and the other is fixed
Stress
Amount of force on a tissue
Strain
amount of give that occurs in a material in response to stress
Explain stress-strain to failure
A tissue has a certain amount of strain that it can take, at high stress there is a lot of strain on the tissue and at some point, it will reach its fracture or breaking point. Example: you can stretch a rubber band pretty far and it gets easier and easier to stretch it the more you go, and at some point the rubber band reaches its failure point and breaks
What are the different regions in the stress-strain curve?
-Toe region (not much stress)
-Elastic region (tissue is starting to stretch and have more stress-strain)
-Plastic region (tissue is in a lot of stress but not quite at failure, tissue starts to get microtears)
-Failure point (tissue reaches its failure point and breaks)
When do tendon ruptures commonly occur?
Tendon ruptures usually occur during eccentric loading
What percentage of strength is lost in ligaments at 6-9 weeks of immobilization?
up to 50%
What two types of tissues are capable of excitation?
Muscle and nerve tissue
What is the definition of torque?
The perpendicular force X the length of the lever arm
What are the three different lever systems?
-First class (teeter totter, fulcrum in middle)
-Second class (wheelbarrow, fulcrum is on opposite site of force)
-Third class (hammer, fulcrum is on the side the force is produced)
What are the two types of muscle fibers?
-Type 1: Slow twitch
-Type 2: Fast twitch
What type of muscle architecture can produce the most force?
Pennate muscles
What type of muscle architecture can move a bony lever the most?
strap
Length-tension relationship
Optimal force generation occurs when the muscle is slightly beyond its resting length and is slightly stretched
Active insufficiency
when the muscle becomes shortened to the point that it cannot generate much force/tension
Passive insufficiency
when the opposing muscle becomes stretched to the point where it can no longer lengthen
Concentric
A shortening contraction
Eccentric
A lengthening contraction
Isokinetic exercise
set speed but variable resistance
Force-velocity relationship
-An inverse relationship
-As force increases, velocity decreases
-As velocity increases, force decreases
Where is the center of mass in the body?
Just anterior to S2 at the top of the pelvis
Newton’s 1st law
a body at rest will stay at rest, and a body in motion will stay in motion until an outside force acts on it
Newton’s 2nd law
acceleration of a body is proportionate to the magnitude of the force acting on it and inversely proportional to the mass (F=ma)
Newton’s 3rd law
For every action, there is an equal and opposite reaction
What is the definition of work?
force times the distance traveled
Power
ability to maintain work over time
Strength
relative ability to generate force
Endurance
Ability to continue muscular effort for a prolonged period of time
How can muscular performance be measured?
It can be measured using torque
Range of motion
angular displacement of the lever arm
Angular velocity
speed of the lever arm
Peak torque
the highest point on the moment-angular position curve
Work (isokinetic exercise)
area under the curve
Describe the arthrokinematics of a convex bone surface rotating on a concave bone surface
The convex surface is rotating in one direction and gliding on the concave surface in the opposite direction
