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Kinesiology Ch1
Terms
Question | Answer |
---|---|
Acceleration | change in velocity of a body over time, expressed in linear (m/sec2) and angular (degrees/sec2) terms |
Accessory movements | slight, passive, nonvolitional movements allowed in most joints (aka Joint Play) |
Active force | push or pull generated by stimulated muscle |
Active movement | motion caused by stimulated muscle |
Agonist muscle | muscle or muscle group that is most directly related to the initiation and execution of a particular movement. |
Anatomic position | reference position used to describe body movement and location. Person is standing fully upright, looking forward, arms at rest by sides, forearms fully supinated, and fingers extended. |
Angle-of-insertion | angle formed between a tendon of a muscle and the long axis of the bone into which it inserts. |
Antagonist muscle | muscle or muscle group that has the action opposite to a particular agonist muscle. |
Arthrokinematics | motions of a roll, slide, and spin that occur between curved articular surfaces of joints. |
Axial rotation | angular motion of an object in a direction perpendicular to its longitudinal axis; often use to describe a motion in the horizontal plane. |
Axis of rotation | an imaginary line extending through a joint around which rotation occurs (aka Pivot Point or the Center of Rotation) |
Bending | effect of a force that deforms a material at right angles to its long axis. A bent tissue is compressed on its concave side and placed under tension on its convex side. A bending moment is a quantitative measure of a bend. See pg 25 for more. |
Center of mass | point at the exact center of an object's mass (aka Center of Gravity when considering weight of gravity) |
Close-packed position | unique position of most joints of the body where the articular surfaces are most congruent and the ligaments are maximally taut. |
Compliance | the inverse of stiffness |
Compression | a force, applied perpendicularly to the contact surface, that pushes or pulls one object directly against another. |
Concentric activation | activated muscle that shortens as it produces a pulling force |
Creep | a progressive strain of a material when exposed to a constant load over time. |
Degrees of Freedom | # of independent directions of movements allowed at a joint. A joint can have up to 3 degrees of translation and rotation. |
Displacement | change in the linear or angular position of an object |
Distal-on-proximal segment kinematics | type of movement in which the distal segment of a joint rotates relative to a fixed proximal segment (aka Open Kinematic Chain) |
Distraction | a force, applied perpendicularly to the contact surface, that pushes or pulls one object directly away from another. |
Eccentric activation | activated muscle that is producing a pulling force while being elongated by another more dominant force. |
Elasticity | property of a material demonstrated by its ability to return to its original length after the removal of a deforming force. |
External force | push or pull produced by sources located outside the body. i.e., gravity and physical contact applied against the body. |
External moment arm | perpendicular distance b/w an axis of rotation and the external force (EF = MF). |
External Torque | product of an external force and its external moment arm (aka External Moment) |
Force | a push or a pull that produces, arrests, or modifies a motion. |
Force-couple | 2 or more muscles acting in different linear directions, but producing a torque in the same rotary direction. |
Force of gravity | potential acceleration of a body toward the center of the earth as a result of gravity. |
Friction | resistance to movement b/w 2 contacting surfaces |
Internal Force (IF) | push or pull produced by a structure located within the body. i.e., active muscle. |
Internal Moment Arm | perpendicular distance b/w the axis of rotation and the internal (muscle) force. |
Internal torque | product of an internal force and its internal moment arm. |
Isometric activation | activated muscle that maintains a constant length as it produces a pulling force |
Joint reaction force | force that exists at a joint, developed in reaction to the net effect of Internal and external forces. Includes contact forces b/w joint surfaces, as well as forced from any periarticular structure. |
Kinematics | branch of mechanics that describes motion of a body, without regard to the forces or torques that may produce motion. |
Kinematic chain | series of articulated segmented links, such as the connected pelvis, thigh, leg, and foot of the lower extremity. |
Kinetics | branch of mechanics that describes the effects of forces and torques on the body. |
Leverage | relative moment arm length possessed by a particular force. |
Line of force | direction and orientation of a muscle's force |
Line of gravity | direction and orientation of the gravitational pull on the body |
Load | general term that describes the application of a force to a body |
Longitudinal axis | axis that extends within and parallel to a long bone or body segment |
Loose-packed positions | positions of most synovial joints of the body in which the articular surfaces are least congruent and the ligaments are slackened. |
Mass | quantity of matter as an object |
Mechanical advantage | ratio of the internal moment arm to the external moment arm. |
Moment arm | perpendicular distance b/w an axis of rotation and the line of force. |
Muscle action | potential of a m. to produce T w/in a particular plane of motion and rotation direction (aka Joint active when referring specifically to a muscle's potential to rotate a joint). i.e., Flexion, extension, pronation, supination, etc. |
Osteokinematics | motion of bones relative to the 3 cardinal, or principal, planes. |
Passive Force | push or pull generated by sources other than stimulated muscle, such as tension in stretched pariarticular connective tissue, physical contact, etc. |
Passive movement | motion produced by a source other than an activated muscle. |
Plasticity | property of a material that remains permanently deformed after the removal of a force. |
Pressure | force divided by a SA. aka Stress |
Productive antagonism | phenomenon in which relatively low-level tension w/in stretched connective tissues performs a useful function. |
Proximal-on-distal segment kinematics | aka Closed Kinematic Chain. type of movement where proximal segment of a joint rotates relative to a fixed distal segment. |
Roll | arthrokinematics term that describes when multiple points on one rotation articular surface contact multiple points on another articular surface. |
Rotation | angular motion in which a rigid body moves in a circular path around a pivot point or an axis of rotation. |
Scalar | quantity, such as speed or temp, that is completely specific by its magnitude and has no direction. |
Segment | any part of a body or limb. |
Shear | a force produced as 2 compressed objects slide past each other in opposite directions (like the action of 2 blades on a pair of scissors) |
Shock absorption | the act of dissipating a force |
Slide | arthrokinematic term describing when a single point on one articular surface contacts multiple points on another articular surface (aka Glide). |
Spin | Arthrokinematic term describing when a single point on one articular surface rotates on a single point on another articular surface (like a top). |
Static Linear Equilibrium | state of a body at rest in which the sum of all forces is equal to zero. |
Static Rotary Equilibrium | State of a body at rest in which the sum of all torques is equal to zero. |
Stiffness | ratio of stress (force) to strain (elongation) within an elastic material, or N/m (aka Young's modulus or modulus of elasticity) |
Strain | ratio of a tissue's deformed length to its original length. May also be expressed in units of distance (m) |
Synergists | two or more muscles that cooperate to execute a particular movement. |
Tension | application of one or more forces that pulls apart or separtes a material (aka distraction force). Used to denote that internal stress within a tissue as its rests being stretched. |
Torque | a force multiplied by its moment arm; tends to rotate a body or segment around an axis of rotation. |
Torsion | application of force that twists a material around its longitudinal axis. |
Translation | linear motion in which all parts of a rigid body move parallel to and in the same direction as every other point in the body. |
Vector | quantity, such as velocity or force, that is completely specified by its magnitude and direction. |
Viscoelasticity | property of a material expressed by a changing stress-strain relationship over time |
Weight | gravitational force acting on a mass. |