Kinesology chapter 2

Isotonic contractions

involve muscle developing tension to either cause or control joint movement. dynamic contractions/causing MOTION. either concentric or eccentric on basis of whether shortening or lengthening respecively

Ruffini's corpuscles

located in deep layers of the skin and the joint capsule. activated by strong & sudden joint movements as well as pressure changes. activation is continued as long as pressure is maintained. essential in detecting even minute joint position changes & providing information as to exact joint angle

Antagonist muscles

located on opposite side of joint from agonist. have the opposite concentric action. work in cooperation with agonist muscles by relaxing & allowing movement

Muscle's ability to shorten

longer muscles can shorten through a greater range . more effective in moving joints through large ranges of motion

2 major types of fiber arrangements

parallel & pennate

Extrinsic

pertaining usually to muscles that arise or originate outside of body part upon which they act. Ex. forearm muscles that attach proximally on distal humerus and insert on fingers

Irritability

property of muscle being sensitive or responsive to chemical, electrical, or mechanical stimuli

Origin

proximal attachment, or the part that attaches closest to the midline or center of the body

Muscles CanNOT

push

All or None Principle

regardless of number, individual muscle fibers within a given motor unit will either fire & contract maximally or not at all. difference between lifting a minimal vs. maximal resistance is the number of muscle fibers recruited. Must have brain involvement

Innervation

segment of nervous system responsible for providing a stimulus to muscle fibers within a specific muscle or portion of a muscle. A muscle may be innervated by more than one nerve & a particular nerve may innervate more than one muscle or portion of a muscle

Action

specific movement of joint resulting from a concentric contraction of a muscle which crosses joint - what happens when it SHORTENS. Ex. biceps brachii has the action of flexion at elbow. Actions are usually caused by a group of muscles working together. Action = shortening. Stretching = ???

Parallel Fiber Arrangement of Fusiform muscles

spindle-shaped with a central belly that tapers to tendons on each end. allows them to focus their power onto small, bony targets. Ex. brachialis, biceps brachii

Stabilizers

surround joint or body part. contract to fixate or stabilize the area to enable another limb or body segment to exert force & move. essential in establishing a relatively firm base for the more distal joints to work from when carrying out movements. Shoulder girdle muscles very important here

Isometric contraction

tension is developed within muscle but joint angles remain constant. static contractions. significant amount of tension may be developed in muscle to maintain joint angle in relatively static or stable position - holding heavy object

Basal ganglia

the next lower level. controls maintenance of postures & equilibrium. controls learned movements such as driving a car. controls sensory integration for balance & rhythmic activities. Complex, learned activities - "habit". Neural control of voluntary movement

Parallel Fiber Arrangement of Flat muscles

usually thin & broad, originating from broad, fibrous, sheet-like aponeuroses. allows them to spread their forces over a broad area Ex. rectus abdominus & external oblique

Pennate Fiber Arrangement

Categorized based upon the exact arrangement between fibers & tendon. Unipennate. Bipennate. Multipennate

Muscle Length - Tension Relationship

Maximal ability of a muscle to develop tension & exert force varies depends upon the length of the muscle during contraction. Generally, depending upon muscle involved. Greatest amount of tension can be developed when a muscle is stretched between 100% to 130% of its resting length

PASSIVE contraction

Movement may occur at any given joint without any muscle contraction whatsoever. solely due to external forces such as those applied by another person, object, or resistance or the force of gravity in the presence of muscle relaxation

Muscles can

ONLY PULL on bones

Muscle Tissue Properties

Skeletal muscle tissue has 4 properties related to its ability to produce force & movement about joints. Irritability. Contractility. Extensibility. Elasticity

Muscle Length - Tension Relationship

Stretch beyond 100% to 130% of resting length significantly decreases the amount of force muscle can exert. Generally, depending upon muscle involved

Force Couples

Two or more muscles pull in 'opposing' directions in order to create a movement

Proprioceptors

internal receptors located in skin, joints, muscles, & tendons which provide feedback relative to tension, length, & contraction state of muscle, position of body & limbs, and movements of joints. Proprioceptors work in combination with other sense organs to accomplish kinesthesis. Proprioceptors specific to muscles in the Muscles spindles or Golgi tendon organs (GTO)

Spinal cord

common pathway between CNS & PNS. integrates various simple & complex spinal reflexes. integrates cortical & basal ganglia activity with various classifications of spinal reflexes. Neural control of voluntary movement

Pacinian corpuscles

concentrated around joint capsules, ligaments, tendon sheaths & beneath skin. activated by rapid changes in joint angle & by pressure changes affecting the capsule. helpful in providing feedback regarding the location of a body part in space following quick movements such as running or jumping

Muscle spindles

concentrated primarily in muscle belly between the fibers. sensitive to stretch & rate of stretch. 1 Muscle stretch occurs2. Impulse is sent to the CNS 3. CNS activates motor neurons of muscle and causes it to contract

Variety of methods to determine muscle action

consideration of anatomical lines of pull. anatomical dissection. palpation. models. electromyography. electrical stimulation. Lines of Pull

Biarticular muscles

cross & act on two different joints. Depending, biarticular muscles may contract & cause motion at either one or both of its joints. Two advantages over uniarticular muscles can cause and/or control motion at more than one joint are able to maintain a relatively constant length due to joint positioning allowing the length/tension relationship to maximized

Insertion

distal attachment, or the part that attaches farthest from the midline or center of the body

Cross section diameter

factor in muscle's ability to exert force. greater cross section diameter = greater force exertion

Parallel muscles

fibers arranged parallel to length of muscle. produce a greater range of movement than similar sized muscles with pennate arrangement

Unipennate muscles

fibers run obliquely from a tendon on one side only. Ex. biceps femoris, extensor digitorum longus, tibialis posterior

Bipennate muscle

fibers run obliquely on both sides from a central tendon. Ex. rectus femoris, flexor hallucis longus

Golgi tendon organ

found in the tendon close to muscle tendon junction. sensitive to both muscle tension & active contraction. much less sensitive to stretch than muscles spindle

Multipennate muscles

have several tendons with fibers running diagonally between them. Ex. Deltoid group

Pennate muscles

have shorter fibers . arranged obliquely to their tendons in a manner similar to a feather. arrangement increases the cross sectional area of the muscle, thereby increasing the power. Can 'fit' more fibers into each central tendon

Cerebral cortex

highest level of control. provides for the creation of voluntary movement as aggregate muscle action, but not as specific muscle activity. interprets sensory stimuli from body to a degree for determine of needed responses. Movements that require thought processes. Learning new movements. Neural control of voluntary movement

Brain stem

integrates all central nervous system activity through excitation & inhibition of desired neuromuscular functions. Puts the signals together in order for them to produce the proper response. functions in arousal or maintaining a wakeful state. Neural control of voluntary movement

Reciprocal Inhibition

Antagonist muscles groups must RELAX when the agonist muscle group contracts concentrically OR eccentrically. Activation of the motor units of the agonists causes a reciprocal neural inhibition of the motor units of the antagonists. This reduction in neural activity of the antagonists allows them to subsequently lengthen under less tension during concentric contraction of agonist

AGONIST VS. ANTAGONIST

Antagonistic muscles produce actions opposite those of the agonist. Ex. elbow extensors are antagonistic to elbow flexors. Elbow movement in returning to hanging position after chinning is extension, but triceps & anconeus are not being strengthened. Elbow joint flexors contract concentrically followed by eccentric contraction of same muscles

Active & Passive Insufficiency

As muscle shortens its ability to exert force diminishes. Active insufficiency is reached when the muscle becomes shortened to the point that it can not generate or maintain active tension. Passively insufficiency is reached when the opposing muscle becomes stretched to the point where it can no longer lengthen & allow movement

Neutralizers

Counteract or neutralize the action of another muscle to prevent undesirable movements such as inappropriate muscle substitutions. contract to resist specific actions of other muscles. ABductors and ADductors of hip actally neutralize each other to maintain straight ahead walking

Parallel Fiber Arrangement

Flat. Fusiform. Strap. Radiate. Sphincter or circular

joint structure

Planes of motion through which a joint is capable of moving

Proprioceptors specific to joints & skin

Ruffini's corpuscles, Pacinian corpuscles & Meissner's corpuscles - important in receiving stimuli from touch not as relevant to kinesthesis

All or None Principle

The number of muscle fibers recruited may be increased by activating those motor units containing a greater number of muscle fibers. activating more motor units. increasing the frequency of motor unit activation

A proportional decrease in ability to develop tension occurs as a muscle is shortened

When shortened to around 50% to 60% of resting length ability to develop contractile tension is essentially reduced to zero. Actin and Myosin can only overlap so far

Motor Unit

a single motor neuron and ALL the muscle fibers it innervates

Isokinetics

a type of dynamic exercise using concentric and/or eccentric muscle contractions. the speed (or velocity) of movement is constant. muscular contraction (ideally maximum contraction) occurs throughout movement. not another type of contraction, as some have described Ex. Biodex, Cybex, Lido. Machine will as hard against you as you work against it

Extensibility

ability of muscle to be stretched back to its original length following shortening (concentric contraction) - spring like

Contractility

ability of muscle to contract & develop tension against resistance when stimulated - Skeletal muscle NOT cardiac muscle

Elasticity

ability of muscle to return to its original length following stretching - rubber band like

Tension in tendons & GTO increase as a muscle contracts

activates the GTO. GTO threshold is reached. Impulse is sent to the CNS . CNS causes the muscle to relax. facilitates activation of the antagonists as a protective mechanism - stops concentric contraction. GTO protects us from an excessive contraction by causing it to relax

Parallel Fiber Arrangement of Radiate muscles

also described sometimes as being triangular, fan-shaped or convergent. have combined arrangement of flat & fusiform. originate on broad aponeuroses & converge onto a tendon. Ex. pectoralis major, trapezius

Synergist

assist in action of agonists. not necessarily prime movers for the action. assist in refined movement & rule out undesired motions. "Secondary movers" - may not have same force generating capability - ie - smaller cross sectional area

The force is applied

at the specific muscle attachment location on the MOVING BONE!!!

Kinesthesis

awareness of position & movement of the body in space

Agonist muscles

cause joint motion through a specified plane of motion when contracting concentrically. known as primary or prime movers, or muscles most involved

Interneurons

central or connecting neurons that conduct impulses from sensory neurons to motor neurons

Gaster or belly or body

central, fleshy portion of the muscle that generally increases in diameter as the muscle contracts. Contains contractile components - Actin and Myosin

Cerebellum

major integrator of sensory impulses. provides feedback relative to motion. controls timing & intensity of muscle activity to assist in the refinement of movement. Feedback as to where your body parts are in space, how they got there and how fast or slow...Neural control of voluntary movement

Stretch reflex

may be utilized to facilitate a greater response. Ex. Quick short squat before attempting a jump. Quick stretch placed on muscles in the squat enables the same muscles to generate more force in subsequently jumping off the floor

Strap muscles

more uniform in diameter with essentially all fibers arranged in a long parallel manner. enables a focusing of power onto small, bony targets Ex. sartorius

Concentric contraction

muscle develops tension as it shortens. occurs when muscle develops enough force to overcome applied resistance. causes movement against gravity or resistance. described as being a positive contraction. force developed by the muscle is greater than that of the resistance. results in joint angle changing in the direction of the applied muscle force. causes body part to move against gravity

Muscle Force - Velocity Relationship

muscle is contracting rate of length change related to the amount of force potential. When contracting concentrically against a light resistance muscle is able to contract at a high velocity. As resistance increases, the maximal velocity at which muscle is able to contract decreases. Eventually, as load increases, the velocity decreases to zero resulting in an isometric contraction. As load increases beyond muscle's ability to maintain an isometric contraction, the muscle begins to lengthen resulting in an eccentric contraction

Eccentric contraction/action

muscle lengthens under tension. occurs when muscle gradually lessens in tension to control the descent of resistance. weight or resistance is allowed to overcome muscle contraction while the muscle controls descending movement . Muscle does not allow resistance to "Drop". controls movement against gravity or resistance. described as a negative contraction. results in the joint angle changing in the direction of the resistance or external force. causes body part to move with gravity or (resistance)

Aggregate muscle action

muscles work in groups rather than independently to achieve a given joint motion