Lecture 1- Biomechanical Principles, Intro to Kinesiology, Basic Structure and Function of Human Joints, Muscle Structure and Function Flashcards
BIOMECHANICAL PRINCIPLES
BIOMECHANICAL PRINCIPLES
What is Newton’s 1st Law?
Law of Inertia
-A body remains at rest or at a constant linear or angular velocity except when compelled by an external force to change its state.
What is inertia?
Amount of energy required to alter the velocity of a body.
What is inertia directly related to?
Directly proportional to mass.
Where is the center of mass typically located on the human body?
Just anterior to 2nd sacral vertebrae in upright.
What is meant by center of gravity?
Point where effects of gravity are completely balanced.
What is the mass moment of inertia?
- Quantity that indicated resistance to change in angular velocity.
- In layman’s terms, the ability to resist changes in rotational speed about a specific axis.
What is the mass moment of inertia dependent on?
Mass, but also the distribution of that mass with respect to the axis of rotation.
Which is easier to move forward during the swing phase of gait of running, a leg that weighs 40 pounds that is flexed at the knee and hip or a leg that weight 40 pounds that is extended at the hip and knee?
Leg that is flexed at the knee and hip, due to the mass being closer to the axis of rotation.
What is Newtons 2nd Law?
Law of Acceleration
- The linear acceleration of a body is directly proportional to the force causing it, takes place in the same direction in which the force acts, and is inversely proportional to the mass of the body.
- F=ma
- The angular acceleration of a body is directly proportional to the torque causing it, takes place in the same rotary direction in which the torque acts, and is inversely proportional to the mass moment of inertia of the body.
- T=mass moment of inertia (I) * angular acceleration (α)
What is acceleration directly proportional with?
What is angular acceleration directly proportional with?
- force
- torque
What is acceleration inversely proportional to?
What is angular acceleration inversely proportional to?
- mass
- mass moment of inertia
What is newtons 3rd Law?
-For every force, there is an equal and opposite directed force.
What does an electrogoniometer measure?
Measures angles of joints and their ROM.
What does an accelerometer measure?
Measure acceleration of either individual segment or whole body.
What is a force plate used for?
Measure the ground reaction forces generated by a body.
INTRO TO KINESIOLOGY
INTRO TO KINESIOLOGY
What is kinesiology?
Study of movement
What are the three cardinal planes of osteokinematics and the motions that occur in each of these planes?
Sagittal
- Flexion and Extension
- Dorsiflexion and Plantarflexion
- Forward and Backward Bending
Frontal (Coronal)
- Abduction and Adduction
- Lateral Flexion
- Radial and Ulnar Deviation
- Inversion and Eversion
Horizontal (Transverse)
- Internal and External Rotation
- Axial Rotation
What is Degree of Freedon (DOF)?
Number of independent directions of movevment allowed at a joint.
What are the degrees of freedom of a uniaxial, biaxial, and triaxial joint?
Uniaxial= 1 DOF Biaxial= 2 DOF Triaxial= 3 DOF
What is the difference between a closed kinetic chain and an open kinetic chain?
CKC- Chain in which the distal segment is fixed and the proximal segment is free to move.
OKC- Chain in which the proximal segment is fixed and the distal segment is free to move.
Does osteokinematics or arthrokinematics describe the motion we visualize with movement?
Osteokinematics
Does osteokinematics or arthrokinematics describe the motion that occurs between the joint surfaces that you cannot visually see when observing?
Arthrokinematics
Describe the convex-concave rule.
- If the moving part is convex, the glide will be opposite of the roll.
- If the moving part is concave, the glide will be in the same direction of the roll.
Describe the direction of the roll and glide for glenohumeral flexion.
- Arm is moving anteriorly
- Roll is moving anteriorly
- Glide is moving posteriorly
Describe the direction of the roll and glide for glenohumeral extension.
- Arm is moving posteriorly
- Roll is occuring posteriorly
- Glide is occuring anteriorly
Describe the direction of the roll and glide for glenohumeral abduction.
- Arm is moving laterally
- Roll is moving superiorly
- Glide is moving inferiorly
Describe the direction of the roll and glide for glenohumeral adduction.
- Arm is moving medial
- Roll is moving inferiorly
- Glide is moving superiorly
Describe the direction of the roll and glide for tibiofemoral flexion.
- Leg is moving posteriorly
- Roll is moving posteriorly
- Glide is moving posteriorly
Describe the direction of the roll and glide for tibiofemoral extension.
- Leg is moving anteriorly
- Roll is moving anteriorly
- Glide is moving anteriorly
What is the third but less common movement in arthrokinematics?
Spin
What is excessive joint play and what may it be a result of?
- hypermobility
- can occur from ligamentous injury or abnormal laxity
The direction of roll and spin is typically in the _______ direction as osteokinematics.
same
Convex on concave- glide and osteokinematics occur in ________ direction.
Concave on convex- glide and osteokinematics occur in _________ direction.
- opposite
- same
If we are performing shoulder abduction, and the arthrokinematics roll but do not glide, what could happen?
Cause impingement in subacromial space.
What is the difference between a loose-packed position (LPP) and a closed-packed position?
- CPP is the point where there is maximal congruency between the bones at the joint. In this position most ligaments and capsules are taut, thus resulting in a stable joint.
- LPP is the point where there is the least congruency between the bones at the joint. In this position the ligaments and capsules are on slack resulting in allowance for increased accessory movements.
Do we perform joint mobilizations in the closed-packed or loose-packed position and why?
Loose-packed position (LPP)
-This is where the joint will be the most mobile.
What is the difference between kinematics and kinetics?
- Kinematics involves looking at the motions without thinking of forces acting on the motions.
- Kinetics is involving the forces and torques acting and thus taking into account mass.
What are the 6 main forces applied to the musculoskeletal system?
Describe them.
- Tension-pulling bone apart
- Compression-pushing bone together
- Bending-…bending
- Shear-force is applied as 2 surfaces move across one another
- Tension-twisting motion
- Combined loading-tension and compression
T or F
After strain in the elastic region is removed from a tissue it results in permanent change. Explain.
False, the point in which permanent change occurs is called the plastic region.
What happens to tissue stretched in the elastic region?
It will return to its original length.
What is the beginning of the plastic region?
What is the ending of the plastic region?
Explain both.
- Yield point- this is where elongation occurs beyond a physiological range
- Ultimate failure point- point where tissue is partially or completely seperated
What is the area that must be drawn taut before tension is measured called?
Toe region
What is viscoelasticity?
Viscocity=resistance to flow
Elasticity=ability to return to original length
Tissues with high viscocity have a _____ resistance to deformation.
high
What is creep and what tissues is creep a part of in the body?
- Creep is the progressive strain of a material when exposed to a constant load over time.
- Connective tissue
What is a good way to visualize creep?
Tree branch with a weight put on the end will eventually start to pull the branch down even though the weight stays the same.
Internal forces can be both _______ and ________.
active and passive
What are some examples of active vs passive forces produced within the body?
Active- muscle
Passive- connective tissue such as ligament or joint capsule
What are examples of external forces?
Things such as gravity or weights
What is the moment (lever) arm?
Perpendicular distance between axis of rotation of the joint and the force being applied