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Kin 702
Vocab Ch. 1
Term | Definition |
---|---|
Acceleration | change in velocity of a body over time, expressed in linear(m/sec2) and angular(deg/sec2) terms |
Accessory movements | slight, passive, nonvolitional movements allowed in most joints(also called joint play) |
Active force | push or pull generated 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 | the generally agreed on reference position of the body used to describe the location and movement of its parts. In this position,a person is standing fully upright and looking forward,with arms resting by the side,forearms fully supinated,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 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 used to describe a motion in the horizontal plane |
Axis of rotation | an imaginary line extending through a joint around which rotation occurs (also called the 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. |
Bending moment | A bending moment is a quantitative measure of a bend. Similar to a torque, a bending moment is the product of the bending force and the perpendicular distance between the force and the axis of rotation of the bend |
Center of mass | point at the exact center of an object's mass(also referred to as center of gravity when considering the weight of the mass) |
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 | number of independent directions of movements allowed at a joint. A joint can have up to three degrees of translation and three degrees of 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(also called an 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 produce by sources located outside the body. these typically include gravity and physical contact applied against the body |
External moment arm | perpendicular distance between an axis of rotation and the external force |
External torque | product of an external force and its external moment arm (also called external moment) |
Force | a push or a pull that produces, arrests, or modifies a motion |
Force-couple | two 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 between two contacting surfaces |
Internal force | push or pull produced by a structure located within the body. Most often, internal force refers to the force produced by an active muscle |
Internal moment arm | perpendicular distance between 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. the joint reaction force includes contact forces between joint surfaces, as well as forces from any periarticular structure |
Kinematics | branch of mechanics that describes the motion of a body, without regard to the forces or torques that may produce the 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 effect 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 a 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 in an object |
Mechanical advantage | ratio of the internal moment arm to the external moment arm |
Moment arm | perpendicular distance between an axis of rotation and the line of force |
Muscle action | potential of a muscle to produce a torque within a particular plane of motion and rotation direction(also called joint action when referring specifically to a muscle's potential to rotate a joint)Terms that describe muscle action;flexion,extension,etc. |
Osteokinematics | motion of bones relative to the three cardinal, or principal, planes |
Passive force | push or pull generated by sources other than stimulated muscle, such as tension in stretched periarticular connective tissues,physical contact, and so forth |
Passive movement | motion produced by a source other than activated muscle |
Plasticity | property of a material demonstrated by remaining permanently deformed after the removal of a force |
Pressure | force divided by a surface area(also called stress) |
Productive antagonism | phenomenon in which relatively low-level tension within stretched connective tissues performs a useful function |
Proximal-on-distal segment kinematics | type of movement in which the proximal segment of a joint rotates relative to a fixed distal segment(also referred to as a closed kinematic chain) |
Roll | arthrokinematic term that describes when multiple points on one rotating 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 temperature, that is completely specified by its magnitude and has no other direction |
Segment | any part of a body or limb |
Shear | a force produced as two compressed objects slide past each other in opposite directions(like the action of two 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(also called 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(also referred to as 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) |
Stress | force generated as a tissue resists deformation, divided by its cross-sectional area(also called pressure) |
Synergists | two or more muscles that cooperate to execute a particular movement |
Tension | application of one or more forces that pulls apart or separates a material(also called a distraction force). used to denote the internal stress within a tissue as it resists 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 a 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 |
Velocity | change in position of a body over time, expressed in linear(m/sec) and angular(deg/sec) terms |
Viscoelasticity | property of a material expressed by a changing stress-strain relationship over time |
Weight | gravitational force acting on a mass |