Muscular System. How Muscles Move- Muscle knows no direction, it just shortens. So when a muscle...

Muscular System

Muscular System

How Muscles Move-Muscle knows no direction, it just shortens.So when a muscle contracts one end of the joint moves

toward the other.

Muscle System

Video on muscle contractionWatch and listen, it is complicated, but I want

you to see it and we will discuss.

Muscle Contraction Videos

https://www.youtube.com/watch?v=CepeYFvqmk4

https://www.youtube.com/watch?v=gJ309LfHQ3M

https://www.youtube.com/watch?v=kvMFdNw35L0

Muscle System

Insertion-the more movable end of the bone, usually more distal.

Origin-attached to the stable bone, the more proximal end of the bone.

Exceptions to the Rule

Latissimus Dorsi-pg 137Proximal (origin) attachment pulls toward

the distal (insertion) attachment, instead of the more common distal attachment pulling toward the proximal. Reversal of muscle function.

Muscle System

So the insertion moves towards the origin.Movable end of the bone moves towards

the more stable end of the bone.

Origin

Insertion

Muscle System

Naming Muscles-use these to find itLocationShapeActionNumber of heads or divisionsAttachmentsDirection size

Muscle System

Tibialis AnteriorExtensor carpi ulnarisSerratus anteriorTriceps BrachiiSternocleidomastoidGo find a muscle and tell me about it. Not

one of mine. It needs to have 2 qualities from the last list.

Muscle System

Muscle Fiber ArrangementParallel fibers are longer and have more range

of motion potential.Oblique fibers are shorter but broad, so have a

greater strength potential for short range.

Muscle System

Muscle System

Parallel MusclesStrap muscles-long and thin, fibers run the

full length of muscle. SternocleidomastoidFusiform muscle-shaped like a spindle,

wide in middle tapers at ends, biceps.Rhomboidal muscle- broad and flat all

through attachments, gluteus maximusTriangular- flat and fan shaped, pec major.

Muscle System

Pectoralis Major Glute Max Biceps

What is each of these??

Muscle System

Oblique muscle-Unipennate-like one

side of a feather, semimembranosusBipennate- like a common feather, bicep

femoris muscleMulipennate- tendons with oblique fibers in

between. Deltoid and subscapularis

Muscle System

Muscle System

What are these??

Characteristics of a Muscle

Stretch a muscle, and it will lengthen (extensibility). Remove the stretch, it will return to normal resting position (elasticity). Stimulate a muscle, and it will respond (irritability) by shortening (contractility). Remove the stimulus and it will return to its normal resting position (elasticity).

Characteristics of muscle

Reverse contractability-When the proximal end moves toward the distal

end it is a reversal of muscle action.Examples???? Look at the bicep.

Rectus femoris

doing a leg raise

vs a sit up.

Muscle System

Tension is the force built up in a muscle.Stretching a muscle builds up passive tensionActive tension is when the muscle is

contracted.Combine active and passive tension, and you

get total tension. Think of kicking a soccer ball, hyperextend,

then contract quads, think of the power you have generated.

Muscle System

The length tension relationship is the optimal contraction of a muscle when it is strongest.

A two joint muscle has an advantage over a one joint muscle. Why?

Read 42-43 together

Muscle System

Active Insufficiency- muscle cannot shorten or contract through full ROM. The muscle will lose tension.

Passive Insufficiency- muscle cannot lengthen or stretch through full ROM.

These are only in two joint muscles like the hamstring and quadriceps.

Pg 43

Stretching

An agonist usually becomes actively insufficient (cannot contract more) before the antagonist becomes passively insufficient (cannot be stretched anymore).

In other words if you contract your hamstring actively to the farthest point, then the quadriceps muscle can be stretched farther

Stretching

To stretch a one joint muscle you must relax the two joint muscles involved.

The soleus is a one joint muscle the gastrocnemius is two. You must flex the knee to stretch the soleus and dorsiflex the ankle.

Tendon action of a muscle (Tenodesis)

Using passive insufficiency to create tenodesis is helpful in quadriplegics.

Lets try it, read page 44 together.

Types of Muscle Contraction

Isometric Contraction-same lengthMuscle contracts producing force but does not

lengthen.

Types of Muscle Contraction

Isotonic Contraction-same tone Muscles contracts and the length of the muscle changes.

Concentric- shorten, attachments move together.accelerated act

Eccentric- lengthen, attachments separatedecelerated act

Examples

Types of Muscle Contraction

Isokinetic Contraction-Resistance to the part varies, but speed stay the

same. In isotonic the resistance remains constant but speed varies.

Think about a biceps curl, when is it hard when is it easy. Does resistance stay the same?

Safer way, you can stop at anytime.Can only be done with special equipmentFUN FACT: The Cybex Orthotron was the first

machine to produce the isokinetic contraction

Roles of Muscles

Muscles assume different roles during joint motion.Agonist/prime mover- causes the motionAssisting mover- depends of angle, size

leverage. Some muscles are only assistersAntagonist- opposite motion of the agonist.

Roles of Mucles

Stabilizer is a a group that supports and allows the agonist to work more efficiently.

Roles of Muscles

Neutralizer- Contracts to prevent the unwanted motion.

For example the biceps muscle flexes the elbow and supinate the forearm. If we want just flexion the pronator teres will act to prevent supination.

Roles of Muscles

Synergist:A muscle that works with one or more other

muscles to enhance a particular motion.

Encompasses the role of the agonist, assisting movers, stabilizers, and neutralizers.

Kinetic Chain

Engineering definition-

Kinetic Chain consists of a series of rigid links connected in such a way as to allow motion.

Human Body

Kinetic chain can be closed or open chain movement that allows motion.

Kinetic Chain

Closed Chain requires that the distal segment is fixed to something, the floor, wall, a bar.

Open Chain is when the distal segment is free to move and proximal segment is stationary.

Lab time