Introduction to Kinesiology - Chapter 1 (PTH516 Pathokinesiology)

Vocabulary cards covering key concepts from the notes on kinesiology, kinematics, kinetics, muscle activation, levers, and tissue mechanics.

Kinesiology

The study of movement.

Kinematics

The study of motion; describes how things move (translation and rotation).

Translation

Linear motion; movement along a straight or curved line (rectilinear or curvilinear).

Rotation

Movement around a pivot point or axis.

Osteokinematics

Movements of bones about a joint axis.

Arthrokinematics

Movements occurring at the joint surfaces between articulating bones.

Sagittal Plane

Plane dividing the body into left and right; flexion/extension occur here.

Frontal Plane

Plane dividing the body into front and back; abduction/adduction and lateral flexion occur here.

Horizontal (Transverse) Plane

Plane dividing the body into upper and lower parts; internal/external rotation occur here.

Axis of Rotation

The pivot line through which angular movement occurs (e.g., vertical/longitudinal, medial-lateral, anterior-posterior).

Vertical (Longitudinal) Axis

An axis running top to bottom through a joint, around which vertical rotations occur.

Medial-Lateral Axis

Axis running side to side through a joint, around which flexion/extension typically occur.

Anterior-Posterior Axis

Axis running front to back through a joint, associated with rotations such as horizontal plane motion.

Degrees of Freedom (DOF)

Number of independent directions of movement at a joint; joints can have up to 3 DOF (e.g., glenohumeral joint = 3).

Accessory Motion

Slight passive translations of joints used to test ligament integrity; may indicate hypo- or hypermobility.

Center of Mass (COM)

The point where the body's mass is considered to be concentrated; standing is anterior to S2, sitting is anterior to T12.

Base of Support (BoS)

The area of contact between the body and support; stability requires the line of gravity to lie within BoS.

Line of Gravity

Vertical line of gravitational force; must pass through BoS for stability.

Closed-Packed Position

Position of maximal joint congruency and ligamentous tightness; minimal accessory motion; usually the most stable.

Loose-Packed Position

Position with maximal accessory movement; mid-range and least congruent.

Kinetics

Branch of mechanics describing the effects of forces on the body.

Force

A push or pull that produces, changes, or stops movement.

F = ma

Newton’s second law: force equals mass times acceleration.

Internal Force

Force generated by structures within the body (e.g., muscles, connective tissue).

External Force

Forces acting from outside the body (e.g., gravity, physical contact).

Joint Reaction Force

The resultant force at a joint from the net effect of internal and external forces, including joint surfaces and periarticular structures.

Moment Arm

Perpendicular distance between the joint axis and the line of action of a force.

Torque (Moment)

Rotational effect produced by a force; torque = force × moment arm.

Force Vector

A vector describing a force by magnitude, direction, orientation, and point of application.

Magnitude of a Force

The strength of the force; represented by the length of the vector.

Spatial Orientation of a Force

The direction in which the force acts in space.

Direction of a Force

Whether the force is positive/upward/rightward or negative/downward/leftward.

Point of Application

Where the force acts on the body (internal vs external attachments).

Internal Torque vs External Torque

Torques generated by internal forces (e.g., muscles) vs external forces; equilibrium occurs when they are equal.

Static Rotary Equilibrium

Condition where internal torque equals external torque, resulting in no angular acceleration.

Roll (Arthrokinematics)

Multiple points on one surface contact multiple points on another surface; commonly described in convex-on-concave patterns.

Slide (Glide)

A single point on one surface contacts multiple points on another surface; described in concave-on-convex patterns in the notes.

Spin

Rotation of one surface on another about a fixed axis with a single contact point.

Convex-on-Concave Arthrokinematics

Roll pattern where a convex surface moves on a concave surface.

Concave-on-Convex Arthrokinematics

Slide pattern where a concave surface moves on a convex surface.

Osteokinematic vs Arthrokinematic Patterns

Osteokinematics describe bone movements; arthrokinematics describe joint surface movements.

Closed-Packed vs Loose-Packed (Joint Positions)

Closed-packed: maximal congruency and minimal accessory motion; Loose-packed: maximal accessory motion, mid-range.

Force (in Kinetics)

A push or pull that can affect movement; analyzed as internal or external in biomechanics.

Net Force

The overall force resulting from the combination of all forces acting on a body; zero when acceleration is zero.

External Forces Example

Gravity and physical contact acting on the body.

Internal Forces

Forces produced by muscles and internal tissues within the body.

Active Forces

Internal forces generated by stimulated muscles; typically the largest internal forces.

Passive Forces

Forces produced by tension in stretched connective tissues (ligaments, joint capsules, intramuscular CT, nerves, vessels, skin).

Isometric Activation

Muscle activation with constant muscle length; external torque equals internal torque.

Concentric Activation

Muscle shortening with external torque less than internal torque.

Eccentric Activation

Muscle lengthening with external torque greater than internal torque.

Agonist

Primary muscle (or group) that produces a movement.

Antagonist

Muscle that opposes the action of the agonist.

Synergist

Muscles that assist the action of the agonist.

Force-Couple

Two or more muscles produce forces in different directions to create rotation about a joint.

Reciprocal Inhibition

Inhibitory effect on antagonists when an agonist is activated, facilitating movement.

Co-contraction

Simultaneous contraction of agonist and antagonist to stabilize a joint.

Passive Insufficiency

In a multi-joint muscle, a limitation of ROM due to its passive length when stretched over two joints.

Active Insufficiency

In a multi-joint muscle, inability to shorten adequately to allow full ROM at the distal segment.

First-Class Lever

Axis between the opposing forces; MA can be

Second-Class Lever

Load between axis and internal force; MA > 1; rare in the body (e.g.,calf).

Third-Class Lever

Axis at one end with external force at the other; internal force between axis and EF; MA < 1 (most common; e.g., elbow flexors).

Mechanical Advantage (MA)

Ratio of IMA to EMA; indicates how much a muscle input can magnify force.

IMA (Internal Moment Arm)

Moment arm of the internal (muscle) force.

EMA (External Moment Arm)

Moment arm of the external force.

Toe Region

Nonlinear part of the stress-strain curve where initial straightening occurs.

Elastic Region

Linear region of stress-strain curve where material deforms elastically.

Plastic Region

Permanent deformation begins beyond the elastic limit.

Yield Point

End of the elastic region; material yields and deforms plastically.

Ultimate Failure Point

Point at which material fails or breaks under stress.

Stress

Internal resistance per unit area within a material under load.

Strain

Relative deformation or elongation of a material under stress.

Creep

Gradual deformation of tissue under sustained load over time.

Rate of Loading

Speed at which a load is applied; affects tissue stiffness (e.g., cartilage stiffens with faster loading).