Biomechanics Quiz 4 Flashcards
Devices for directly measuring joint angles:
- Goniometer
2. Electrogoniometer
range of motion can be measured as:
- Maximum joint angle
2. Excursion: total movement
What can restrictions in range of motion can impair?
performance
Excessive or restricted range of motion can indicate what?
injury or disorder
What is osteokinematics?
the motion bones relative to the three cardinal planes of the body (horizontal, sagittal, frontal)
Osteokinematics: axis of rotation – located? example?
located: through the convex member of the joint
ex: shoulder
Osteokinematics: angular degrees of freedom
“accessory movement”
What is Arthrokinematics?
the motion that occurs between articular surfaces of joints.
examples of Arthrokinematics
–Congruency
–Surface Area
–Guide
Arthrokinematics: what is roll?
Multiple points along one rotating articular surface contact multiple points on another articular surface.
Arthrokinematics: what is slide?
A single point on one articular surface contacts multiple points on another articular surface.
Arthrokinematics: what is spin?
A single point on one articular surface rotates on a single point on another articular surface.
One primary way that a bone rotates through space is by:
rolling of its articular surface against another bone’s articular surface.
“roll-and-slide”
The rolling of the typically involves:
a concurrent, oppositely directed slide.
“roll and spin and slide”
Musculoskeletal Torques:
moment arm
the perpendicular distance from an axis to the line of force
Angular Kinetics: internal. produced from?
structures within the body
Angular Kinetics: internal: active is generated by?
Generated by stimulated muscle, generally but not necessarily under volitional control.
Angular Kinetics: internal: passive is generated by?
Generated by tension in stretched periarticularconnective tissues, including the intramuscular connective tissues, ligaments and joint capsules.
Angular Kinetics: external. produced by? originate from?
forces acting outside the body.
originate from either:
- gravity pulling on the mass of a body segment
- an external load, such as a weight or physical contact
Musculoskeletal Torque
a TORQUE rotates an object about an axis of rotation.
whereas force pushes and pulls object linearly
TORQUE can be considered what in relation to force?
a rotatory equivalent to force.
Moment Arm (MA):
Perpendicular distance between the joint axis of rotation and the force.
Torque formula
Torque = force x MA
Internal Torque formula
Internal Force x Internal MA (D)
External Torque formula
External Force x External MA (D)
Static equilibrium occurs when:
internal torque = external torque
Musculoskeletal Torque: Joint angle can alter …
… the torque producing capabilities of muscle.
The larger the moment arm
The smaller the resistance
3 Types of Muscle Interaction:
- Isometric
- Concentric
- Eccentric
Isometric Activation
when a muscle is producing a pulling force while maintaining a constant length
*NOTE: the internal torque produces within a given plane at a joint is equal to the external torque; hence, there is no muscle shortening or rotation at the joint. (i.e. static equilibrium)
Concentric Activation
a muscle produces a pulling force as it contracts (shortens).
*NOTE: , the internal torque at the joint exceeds the opposing external torque. The contracting muscle creates a rotation of the joint in the direction of the pull of the activated muscle.
Eccentric Activation:
a muscle produces a pulling force as it is being elongated by another more dominant force.
*NOTE: the external torque around the joint exceeds the internal torque. The joint rotates in the direction dictated by the relatively larger external torque.
