Chapter 2 Flashcards
How do body parts move?
External or Internal force
Internal force is responsible for movement and positioning of the bony segments of the body is the action of the skeletal muscle
Skeletal Muscle Basics
- Over 600 skeletal muscles make 40-50% of body weight
- 215 pairs of skeletal muscles work together for opposite actions
Aggregate Muscle Action
Muscles work in groups rather than independently to achieve a given joint motion
4 properties of skeletal muscle tissue
- Irritability/Excitability (sensitive to stimuli)
- Contractility (ability to develop tension)
- Extensibility (ability to be passively stretched)
- Elasticity (able to return to resting length)
What effects do muscles’ shape and fiber arrangements have?
- Muscles ability to exert force is greater or lesser
- Range through which it can effectively exert force onto bones
Muscles’ Cross Sectional Area
- factor in muscles ability to exert force
- greater cross section diameter is greater force exertion
Muscle’s ability to shorten
longer muscles can shorten through a greater range
more effective in moving joints through large ranges of motion
Muscle Shapes
flat, fusiform, strap, radiate, sphincter or circular
Flat
thin and broad
ex: rectus abdominis and external oblique
Fusiform
spindle shape
ex: brachioradialis and brachialis
Strap
long parallel
ex: sartorius
Radiate
triangular
ex: pectoralis major and trapeziusS
Sphincter or Circular
open & close circular
ex: orbicularis oris and oculi
Pennation Angle
Pennate Angles have greater cross section and force capacity
Fibers run obliquely
Unipennate
Bicepennate
Multipennate
run obliquely on 1 side (biceps femoris)
run obliquely on 2 sides (rectus femoris)
run obliquely on many sides (deltoid)
Action
- specific movement of joint resulting from a concentric contraction of a muscle which crosses joint
Innervation
- segment of nervous system defined as being responsible for providing stimulus to fibers
- a muscle can be innervated by more than one nerve
Tendon
fibrous connective tissue, often cordile in appearance
connects muscles to bones
Aponeurosis
A tendinous expansion of dense fibrous connective tissue that is sheet-like/ribbon like
looks like a flattened tendon
Fascia
A sheet or band of fibrous connect tissue that binds muscles, organs, and soft tissues
In certain places like joints like the wrist and ankle
Origin
the proximal attachment of a muscle or the part that attaches closest to the midline or center of body
least moveable
Insertion
the distal or part that attaches furthest away from the midline or center of the body
most movable part
Name the two types of muscle contractions and describe them.
Isometric: Static / joint angle stays the same
Isotonic: Dynamic / joint movement
Name the two types of isotonic contractions
Concentric: Muscle shortening / More force than applied resistance
Eccentric: Muscle lengthening / more resistance than muscle force
Agonist Muscle
Some are primary mover muscles that contribute heavily to joint motion and some are assister agonist movers that contribute less
Antagonist Muscles
- Located opposite of joint from agonist
- opposite concentric action
- contralateral muscles
- work in cooperation with agonist muscles through relaxation
EX: biceps antagonist to triceps
Stabilizer Muscles
- surround joint or body part
- contract to stabilize the area to enable another limb or body part for movement and force
Synergist Muscles
- assist in action of agonists
- assist in refined movement and rule out undesired motion
Neutralizer Muscles
- counteract action of another muscle to prevent undesired movements
Force Couples
- 2 or more forces are pulling in different directions
Lines of Action
Muscles pull toward the angle of pull, they don’t push
3 types of neurons
Sensory- afferent
Motor- efferent
Interneuron- communicator/connector
Peripheral Nervous System
SAME DAVE
Sensory Afferent Motor Efferent
Dorsal Afferent Ventral Efferent
Proprioception
SUBCONCIOUS MECHANISM that regulates posture and movement
Kinesthesis
CONCIOUS AWARENESS of the position and movement of body in space
Golgi Tendon Organ
- proprioceptor that is sensitive to muscle tension and active contraction
- requires greater stretch to be activated
Muscle Spindle
- proprioceptor that runs parallel with muscle fibers that is sensitive to stretch
Myotatic Reflex
- when stretch occurs, an impulse (from spindle and GTO) is sent to CNS then activates motor neurons and contraction happens
Patellar Tendon Reflex
Stretches muscle and hits muscle spindle and GTO and you kick to relieve tension
Motor Unit
- “All or None” Activation
If an action potential reaches the motor unit, all fibrs with it are 100% activated - fingers have more small motor units than big muscles like glutes
Subthreshold Stimulus
No contraction due to lack of strength of stimulus
Threshold Stimulus
Single motor unit
Submaximal Stimulus
Multiple Motor Units
Maximal stimulus
All motor units, past this has no effect
Summation
when a successive stimuli is placed before relaxation stage and combine for a sustained contraction
Tetanus
Stimuli so high that no relaxation should occur
(think about tetanus and all the muscles contract up)
Treppe
multiple maximal stimuli provided to rested muscle ay a low frequency to allow complete relaxation between contractions
