Kinesiology and Human Movement Overview

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Questions and Answers

What type of muscle fibers are predominantly found in antigravity muscles?

Type III fibers

Type IV fibers

Type II fibers

Type I fibers (correct)

What is the primary role of a synergist muscle during an activity?

To decrease the overall force produced by the agonist

To act as a passive muscle during eccentric contraction

To stabilize the proximal joints for distal joint movement (correct)

To oppose the action of the agonist

What effect does increasing temperature have on the viscosity of muscle tissue?

Changes viscosity only temporarily

Decreases viscosity (correct)

Increases viscosity

No effect on viscosity

As an individual ages, which type of muscle fiber is likely to decrease in amount?

Type II fibers Signup and view all the answers

What is the definition of extensibility in muscle characteristics?

The ability to stretch, elongate, or expand Signup and view all the answers

What occurs during the plastic range of viscoelasticity?

Some of the tissue ruptures due to excessive stress Signup and view all the answers

Which term describes a muscle that is the principal muscle producing a motion?

Agonist Signup and view all the answers

Which type of muscle fibers are associated with stamina and sustained activity?

Type I fibers Signup and view all the answers

What does viscosity refer to in muscle characteristics?

Resistance to deformation or change in shape Signup and view all the answers

Which of the following muscles is classified as a mobility muscle?

Gastrocnemius Signup and view all the answers

What does the term 'kinematics' specifically deal with?

Types of motion without reference to forces Signup and view all the answers

Which plane of motion divides the body into anterior and posterior sections?

Frontal plane Signup and view all the answers

In which type of joint movement do two segments move around one axis?

Uniaxial Signup and view all the answers

What characterizes a closed kinematic chain movement?

Proximal and distal segments move as a single unit Signup and view all the answers

Which of the following motions is associated with the sagittal plane?

Flexion and extension Signup and view all the answers

What is the main focus of kinetics?

Forces that produce or resist movement Signup and view all the answers

What does the convex-concave relationship imply during joint movement?

Concave surface moves in the opposite direction to the bone segment Signup and view all the answers

Which type of motion is exemplified by a fully flexed elbow performing supination?

Rotary motion Signup and view all the answers

What is the main objective of accessory movements in joint function?

To allow for pain-free motion Signup and view all the answers

How is torque defined in biomechanics?

Force applied around an axis of motion Signup and view all the answers

Which of the following best describes an open kinematic chain?

The distal segment moves independently in space Signup and view all the answers

What is the position called where the joint surfaces fit perfectly together?

Closed packed position Signup and view all the answers

In the context of forces, what does friction refer to?

The resistance between two surfaces in contact Signup and view all the answers

Which of the following describes the motion of medial and lateral rotation?

Occurs in the transverse plane Signup and view all the answers

What occurs when the total magnitudes of forces turn in opposite directions without motion?

The forces equal each other. Signup and view all the answers

What is the average resting membrane potential value for a muscle cell?

-85 mV Signup and view all the answers

What characterizes hyperpolarization in a neuron?

It increases the voltage requirement for action potential. Signup and view all the answers

Which neurotransmitter is primarily involved in signal transmission at the neuromuscular junction?

Acetylcholine Signup and view all the answers

What is the primary role of troponin in muscle contraction?

It binds to calcium ions. Signup and view all the answers

What is the significance of the refractory period in muscle physiology?

It is a time when action potentials cannot be generated. Signup and view all the answers

How do excitatory synapses affect the postsynaptic membrane?

They cause depolarization. Signup and view all the answers

Which structure is responsible for storing and releasing calcium ions during muscle contraction?

Sarcoplasmic reticulum Signup and view all the answers

What is the role of the sliding filament theory in muscle contraction?

Actin filaments slide past myosin filaments. Signup and view all the answers

Which motor neuron type innervates extrafusal muscle fibers?

Alpha motor neurons Signup and view all the answers

What defines the all or none law in muscle physiology?

All fibers in a motor unit contract or relax simultaneously. Signup and view all the answers

Which factor affects the gradation of strength of muscle contraction?

The number of motor units activated. Signup and view all the answers

What is the main function of Golgi tendon organs?

Detect force or tension in muscles. Signup and view all the answers

What happens during muscle relaxation after contraction?

Active sites on actin are covered. Signup and view all the answers

What is the term for a permanent change in tissue length due to stress?

Necking Signup and view all the answers

In the context of muscle strength, what characteristic do pennate muscles have?

They produce greater forces due to their structure. Signup and view all the answers

What occurs when a muscle is elongated beyond its slack point?

Passive stretching of fascia Signup and view all the answers

What happens to active tension when a muscle is lengthened beyond a certain point?

It decreases due to fewer available cross-bridges. Signup and view all the answers

Which statement about muscle strength and age is accurate?

Muscle strength generally decreases after age 30. Signup and view all the answers

What is the result of active insufficiency in a muscle?

Minimal force production at shortest length. Signup and view all the answers

What describes the creeping effect in muscle tissue?

Sustained elongation under low-level stress over time. Signup and view all the answers

What is delayed-onset muscle soreness (DOMS)?

A gradual onset of soreness that lasts up to 10 days. Signup and view all the answers

Which type of muscle fibers are generally recruited first during muscle contraction?

Slow-twitch fibers Signup and view all the answers

How does muscle size affect strength?

Larger cross-sectional areas correlate with greater strength. Signup and view all the answers

What characterizes the failure range of a muscle’s stress-strain curve?

Tissue ruptures and continuity is lost. Signup and view all the answers

What happens to muscle strength after puberty?

Males typically have 50% more muscle mass. Signup and view all the answers

Which component of muscle tissues provides parallel elasticity?

Fascial fibers Signup and view all the answers

Study Notes

Course Overview

Standard anatomic position: standing, head facing forward, palms facing forward, feet shoulder-width apart.
Understanding of human movement is crucial to prevent injury and enhance performance.

Kinesiology

Study of human movement and its aesthetic and scientific aspects.
Involves understanding forces acting on the body.

Cardinal Planes

Frontal (Coronal) Plane: Divides body into front and back; motions include abduction, adduction, lateral flexion.
Sagittal Plane: Divides body into left and right; motions include flexion, extension, and dorsiflexion/plantarflexion.
Transverse Plane: Divides body into upper and lower parts; motions include rotation, pronation, supination.

Forces Affecting Motion

Gravity, muscle tension, external resistance, and friction are fundamental forces influencing motion.

Biomechanics

Application of mechanical principles to living organisms.
Differentiates between statics (bodies at rest or uniform motion) and dynamics (accelerating/decelerating bodies).

Kinematics

Examines motion types without considering force origins.
Osteokinematics: Movements between bony partners at joints.
Arthrokinematics: Minute movements within joints.

Degrees of Freedom

Number of planes in which joints can move; maximum is three degrees (e.g., shoulder and hip).
Uniaxial joints: One plane of motion (e.g., hinge or pivot joints).
Biaxial joints: Two planes of motion (e.g., condyloid or saddle joints).
Triaxial joints: Three planes of motion (e.g., ball-and-socket joints).

Kinematic Chains

Closed Kinematic Chain (CKC): Distal segment is fixed; benefits stability (e.g., chin-up).
Open Kinematic Chain (OKC): Distal segment moves in space; allows variability (e.g., reaching movements).

Joint Mechanics

Rolling, sliding, and spinning are the primary joint surface motions.
Open packed position: Joints are incongruent; ligaments and capsules are slack. Essential for joint movement.
Close packed position: Joints fit perfectly; provides mechanical stability.

Types of Motion

Translatory motion: Movement along an axis (e.g., elevator motion).
Curvilinear motion: Movement along a curved path (e.g., tossing a ball).
Angular motion: Movement around a pivot (joint) with variable velocities depending on distance from the pivot.

Newton’s Laws of Motion

First Law: A body at rest stays at rest; a body in motion stays in motion unless acted upon by an external force.
Second Law: Acceleration is proportional to net forces acting on a body and inversely proportional to its mass (F=ma).
Third Law: For every action, there's an equal and opposite reaction (e.g., ground reaction force).

Leverage and Force Applications

Levers: Rigid bars rotating around a fulcrum; consist of axis, resistance, and force.
First-Class Lever: Equal forces on either side can gain either force or distance (e.g., seesaw).
Second-Class Lever: Resistance is between the force and the axis; provides force advantage (e.g., wheelbarrow).
Third-Class Lever: Most common in human body; moves smaller weights a large distance (e.g., bicep curl).

Torque and Forces

Torque is the effective force applied in an arc around an axis (T = f.d).
Importance of force vectors: Forces have magnitude and direction; resultant forces combine multiple vectors.

Clinical Relevance

Understanding kinematics and biomechanics is crucial for evaluating and treating movement problems, enhancing performance, and preventing injuries.### Lever System and Torque
Equal total magnitudes in opposite directions prevent motion.
Greater distance from the pivot increases torque and resistance needed.

Movement System

Muscle activity involves interaction between musculoskeletal and nervous systems.
Communication is crucial for movement execution.

Resting Potential

Defined as a state when no action is occurring; typically has a negative value.
Average resting membrane potential is around -85 mV.
Nerve cells: -70 mV, Muscle cells: -90 mV, Cardiac muscle: -50 to -60 mV.

Irritability and Depolarization

Neurons and skeletal muscles can react to stimuli due to specific membrane characteristics.
Depolarization occurs when nervous and muscular tissues react, resulting in a more positive membrane potential.

Action Potential

Electrochemical messages are propagated through nervous and muscular systems.
Potential difference arises from ion imbalances across the cell membrane.

Repolarization

An active process after depolarization that restores the membrane to resting potential.

Hyperpolarization

Increased voltage requirement due to inhibitory synapses; makes action potential generation difficult.

Refractory Period

The state in which depolarization is still challenging to achieve.

Neurotransmission

Neurotransmitters send control signals to other neurons or muscles.
Synapses can be excitatory (causing depolarization) or inhibitory (causing hyperpolarization).

Nerve Fibers

Type A: Largest myelinated axons, including subtypes A-alpha, A-beta, A-gamma, and A-delta.
Type B: Intermediate diameter, myelinated.
Type C: Smallest diameter, unmyelinated.

Nervous System Structure

Upper motor neurons originate in the CNS.
Lower motor neurons located in ventral horn gray matter.
Interneurons connect within the spinal cord.

Sensory and Motor Fibers

Group I fibers transmit impulses from muscle spindles; Group II fibers from secondary muscle spindle receptors.
Alpha motor neurons innervate extrafusal muscle fibers; Gamma motor neurons innervate intrafusal fibers.

Organization of Muscle

Muscle fibers vary in length and diameter, constructed from myofibrils.
Myofilaments consist of actin (thin) and myosin (thick) filaments.

Muscle Contraction Mechanics

Myosin filaments shorten from 2.5μm (relaxed) to 1.5μm (fully contracted).
Crossbridge formation between myosin heads and actin is crucial for contraction.

Sliding Filament Theory

Actin and myosin slide past each other during muscle contraction.
Crossbridges link with active sites on actin, resulting in muscle shortening.

Excitation-Contraction Coupling

Muscle action potential arrival depolarizes the sarcolemma, releasing calcium ions from the sarcoplasmic reticulum.
Calcium ions interact with troponin, revealing active sites on actin for contraction.

Motor Unit and Muscle Tension

Each motor unit comprises an alpha motor neuron and associated muscle fibers.
Innervation ratio reflects the number of fibers per motor unit, influencing muscle control.
All or none law states entire motor unit fibers contract or relax simultaneously.

Strength of Muscle Contraction

Size principle: Smaller motor units activate first.
Recruitment principle: More motor units lead to greater muscle tension.
Rate coding principle: Frequency of stimulation affects tension generation.

Joint Receptors and Muscle Proprioception

Joint receptors monitor joint position and movement rate.
Golgi tendon organs sense force or tension within muscles.

Muscle Spindle Functionality

Muscle spindles provide feedback on the length of a muscle and stretching rate.
La afferent fibers detect both stretch length and velocity.

Types of Muscle Contraction

Isometric: Muscle contracts without changing joint angle; stabilizes joints.
Concentric: Muscle shortens, generating positive work; accelerates body segments.
Eccentric: Muscle lengthens against resistance; controls speed and absorbs shock.

Implication of External Forces

Muscle lengthening and eccentric contractions often occur against gravity, controlling the speed of movement.### Muscle Fiber Types
Muscle composition varies per individual, with some having more type I (slow-twitch) or type II (fast-twitch) fibers.
Muscle fiber types can change over time due to activity levels and hormone influences.
Aging is associated with a decrease in type II muscle fibers.

Muscle Categories

Antigravity Muscles: Aid posture against gravity; predominantly utilize type I fibers.
- Include muscles like soleus, quadriceps, and erector spinae.
Mobility Muscles: Designed for swift movements; contain more type II fibers.
- Examples: gastrocnemius and hamstrings.

Muscle Function

Relationships among agonists (prime movers), antagonists (opposing muscles), and synergists (assisting muscles) can change based on activity and body position.
Antagonists can be inactive during certain activities but allow movement by passive elongation or shortening.

Muscle Characteristics

Viscosity: Affects tissue deformation resistance.
- Increased temperature lowers viscosity, making tissues easier to stretch.
Elasticity: Ability to return to original length after stretching.
Extensibility: Capability of elongation under force.

Stress-Strain Curve

Illustrates tissue response to stress:
- Toe Region: Tissue is crimped; slack is taken up when stress is applied.
- Plastic Range: Permanent deformation occurs with continued stress.
- Failure Range: Tissue ruptures completely if stress exceeds tolerance.

Muscle Strength Mechanics

Influenced by muscle size, architecture, moment arm length, and contraction speed.
- Larger cross-sectional area typically results in greater strength.
Fiber Architecture:
- Fusiform: Provides speed through parallel alignment.
- Pennate: Produces greater force due to oblique angles and larger cross-sectional area.

Length-Tension Relationships

Optimal muscle tension occurs at resting length, where actin-myosin overlap is maximized.
Muscle strength generally peaks in the 20s and declines with age; males typically have greater muscle mass post-puberty.

Functional Excursion

Refers to the distance a muscle can shorten after being elongated.
Passive Insufficiency: Occurs when a muscle is stretched over multiple joints, limiting its ability to shorten effectively.
Active Insufficiency: Happens in multijoint muscles when they are at their shortest length, reducing force production.

Exercise-Induced Muscle Injury

Delayed-Onset Muscle Soreness (DOMS) typically starts 24 hours post-exercise, lasting up to 10 days.
- Signs include decreased range of motion and reduced muscle force.
- Recovery time varies between 5 to 30 days.

Hamstring Strain

Associated with activities like sprinting; can result in severe injury with muscle tearing and bleeding.
Symptoms include sudden onset pain, often causing athletes to collapse during activity.

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Description

This quiz covers the fundamental aspects of kinesiology, including the standard anatomic position, the cardinal planes of movement, and the forces that affect human motion. Understanding these concepts is vital for preventing injuries and improving physical performance in various activities.