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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
