Ch.2 - Neuromuscular Fundamentals

How many muscles in the body?

over 600

What is aggregate muscle action?

215 pairs of muscles that work together to perform opposite motions (biceps/triceps)

What are muscles named by?

shape, size, number of divisions, location, point of attachment, action, combination of above, shape, and size of fiber arrangement affect muscles ability to exert force, bigger the muscle diameter the greater the force it can produce, longer muscles can produce a greater ROM

What are the muscles shapes?

flat, strap, sphincter, bipennate, Fusiform, radiate, unipennate, multipennate

What are parallel fiber arrangements?

Flat muscles, usually thin and broad, originating from broad, fibrous, sheet-like aponeuroses

What is an example of parallel fiber arrangement?

rectus abdominis and eternal oblique

what are 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

What is an example of fusiform muscles?

brachialis, biceps brachii

What are 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

What is an example of strap muscles?

sartorius

What are radiate muscles?

also described someties as being triangular, fan-shaped or convergent. Have combined arrangement of flat and fusiform, originate on broad aponeuroses and converge onto a tendon

What is an example of radiate muscles?

pectoralis major, trapezius

What are sphincter or circular muscles?

technically endless strap muscles, surrounded openings and function to close then upon contraction

What is an example of sphincter or circular muscles?

orbicularis oris surrounding the mouth

What are pennate muscles?

think feathers, have short 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. Categorized based upon the exact arrangement between fibers and tendons

What are the types of pennate muscles?

unipennate, bipennate, multipennate

What are unipennate muscles?

fibers run obliquely from a tendon on one side only

What is an example of unipennate muscles?

biceps femoris, extensor digitorum longus, tibialis posterior

What are bipennate muscles?

fibers run obliquely on both sides from a central tendon

What is an example of bipennate muscles?

rectus femoris, flexor hallucis longus

What are multipennate muscles?

have several tendons with fibers running diagonally between them

What is an example of multipennate muscles?

deltoid

Which two pennate muscles produce the strongest contractions?

bipennate and multipennate

What is irritability?

sensitivity of muscle to respond to stimuli (chemical, electrical, or mechanical)

What is contractility?

ability to contract and develop tension

What is extensibility?

ability to be passively stretched beyond its normal resting length

What is elasticity?

ability to return to its original resting length following stretching

What are intrinsic muscles?

muscles pertaining solely to the body part they affect (muscles of the hand)

What are extrinsic muscles?

muscles that originate outside of the body part they affect (muscles of the forearm affecting the movement of the hand)

What is an action?

specific movement of joint resulting from a concentric contractions of a muscle crossing a joint

What is an example of an action?

biceps brachii has an action of flexing the elbow

What is innervation?

the segment of the nervous system responsible of providing a stimulus to muscle fibers within a muscle or portion of muscle. Muscles may have more than one nerve. Nerve muscles may innervate more than one muscle

What is amplitude?

the range of muscle fiber length between maximal and minimal lengthening

What is gaster?

belly of the muscle, muscles pull both ends toward the gaster when contracting. Gaster increases in diameter when contracting

What are tendons?

tough, flexible, card-like band that connects muscles to bones

What is aponeurosis?

sheet-like tissue that binds muscle to bone

What is Fascia?

sheet or band of fibrous connective tissue that envelopes, separates, or binds together parts of the body, such as muscles, organs, or other soft tissue. Around certain joints, it forms a retinaculum to keep tendons in place (wrist, ankle, knee)

What is origin?

the proximal attachment of a muscle or the one closest to the midline

What is insertion?

the distal attachment of a muscle or furthest from the midline

What are types of muscle contractions?

can be used to cause, control, or prevent joint movement. All are classified as either isometric or isotonic

What are isometric muscle contractions?

static contraction. Classified as concentric and eccentric.

What are isotonic muscle contraction?

dynamic contraction

What are concentric isotonic contractions?

positive contraction, overcoming gravity or resistance, force caused by muscle in greater than resistance. The flexion part of a bicep curl

What are eccentric isotonic contractions?

muscles lengthening under active tension. Muscles lessens in tension to control the decent of the resistance. The extension part of a bicep curl

What are isokinetics?

exercises that keep the muscles in constant concentric/eccentric contractions while maintaining a constant velocity…AKA very tiring!

What are agonist muscles?

primary movers (contract)

What is an example of agonist muscles?

knee flexion: hamstrings are the primary mover

What are antagonist muscles?

opposite concentric action from antagonist

What is an example of antagonist muscles?

lengthen to allow for contraction. Quadriceps muscles are the ____ of hamstrings in knee flexion

What are stabilizer muscles?

surround joint or body part and contract to stabilize the area to enable another limb or body part to exert force and move

What is an example of stabilizer muscles?

muscles of the glenohumeral joint and scapula contract to stabilize the humerus during a bicep curl

What are synergist muscles?

muscles that assist the agonist but are not necessarily the prime mover

What are helping synergists?

help muscles move in the desired action but also prevent undesired action

What is an example of helping synergists?

The semitendinosus muscle of the hamstring helps in hip extension but also limits internal rotation

What are true synergist muscles?

contract to prevent undesired motion, but do not aid in the agonist action

What is an example of true synergist muscles?

wrist extensor muscles are _______ to finger flexors when hand grasps an object…wrist extensors prevent wrist from flexing with finger flexors. Finger flexors and wrist flexors are the same muscle group.

What are neutralizer muscles?

meutralize the action of other muscles to prevent undesired movement

What is an example of neutralizer muscles?

When the biceps brachii contracts it attempts to flex the elbow and supinate the forearm. When only supination is desired, the triceps brachii contracts to neutralize the flexion

What are force couples?

occur when two or more forces are pulling in different directions on an object causing the object to rotate on its axis