MUSCLE ANATOMY AND PHYSIOLOGY

TYPES OF MUSCLE PATTERNS

PARALLEL PENNATE CONVERGENT CIRCULAR

PARALLEL MUSCLE The fascicles are parallel. They are long fibers, which can contract to 75% of their length. They contract a long way, but they are relatively weak, because there are relatively few fascicles. E.g. Sternocleidomastoid.

Arrangement of Fascicles in

Muscles Figure 11.3

PENNATEPENNATE (means “feather shape”) MUSCLES: three types:

UNIPENNATE; looks like half a feather. The fascicles are short, but there are more of them. They are stronger, but do not have the same length contraction ability of the parallel muscles.

BIPENNATE are fascicles that insert into the tendon from both sides; they are stronger than unipennate.

MULTIPENNATE are the strongest (biceps femoris). The fascicles are in multiple bundles inserting on one tendon

PENNATE

CONVERGENTCONVERGENT MUSCLE has more fibers

than parallel, but contracts a greater distance than pinnate. E.g. Pectoralis major.

CIRCULAR MUSCLECIRCULAR MUSCLE (Sphincter) is arranged

in a circle, with a small area of tendon on the sides. It allows closure of the eyes, mouth, etc. They are not very strong, but they don’t need to be.

TERMS: ORIGIN = The region which usually doesn’t move when the

muscle contracts. Look at the biceps brachii; does the shoulder move when I bend my arm? No; the shoulder = origin.

INSERTION= The point of attachment that moves; bend arm, radial tuberosity = attachment.

AGONIST = The main muscle for a particular action; bend arm, biceps = agonist.

ANTAGONIST = Does the opposite action; bend elbow, antagonist extends. Every muscle in the body has to have an antagonist.

SYNERGIST = The muscle that helps the agonist. There are several muscles that assist when the arm is bent.

Muscle Attachments

Muscle Types Skeletal:

striated Voluntary Moves the skeleton

Smooth: no striations Involuntary Found in organs and lining of blood vessels

Cardiac: striated involuntary

Skeletal Muscle Characteristics Contractility

The ability to shorten with force However, they lengthen passively, by gravity or by the contraction of an

opposing muscle. Excitability

Capacity to respond to a stimulus (nerves) Extensibility

Can be stretched After a contraction, they can be stretched to their normal resting length

and beyond to a limited degree. Elasticity Can recoil to their original resting length after they have been stretched

Has several nuclei per cell, unlike smooth and cardiac muscle

SKELETAL MUSCLE Theses are very long fibers (biceps muscle

can be 8-10 cm). They have thousands of nuclei because they

start from many stem cells that fuse together into one skeletal muscle fiber.

Skeletal Muscle Myoblasts exist in adults, so muscle heals

well. A muscle cell torn in half can regenerate. There are almost no muscle diseases for this

reason (muscular dystrophy is the main muscle disease).

Skeletal Muscle: Longitudinal section

In skeletal muscle fibers, there are light and dark stripes called striations, which can be seen under a microscope.

Skeletal Muscle The plasma membrane of muscles is called a

SARCOLEMMA. The cytoplasm of muscle cells is called

SARCOPLASM. Muscle cells contain many mitochondria and

other organelles. One type of unusual organelle found only in

muscle cells is called a myofibril. They are packed in bundles and fill up most of the cell.

• MUSCLE MYOFIBRILS • Cylindrical organelles found within muscle cells

• Contain actin and myosin myofilaments

• Extend from one end of the muscle fiber (muscle cell) to the other

• Contain sarcomeres joined end to end.

Skeletal Muscle: Longitudinal section

These striations (stripes) are caused by dark and light bands.

SARCOMERES

The striations result from the internal structure of SARCOMERES within the sarcoplasm.

The sarcomere is the basic structural and functional unit of skeletal muscle. The sarcomere is what contracts.

Actin and Myosin Sarcomeres consist of two types of myofilaments

made out of protein: thin (ACTIN) myofilaments

Look like two strands of beads twisted together.

thick (MYOSIN) myofilaments. Both ends of a thick filament are studded with knobs

called myosin heads (look like little golf clubs).

Sarcomere model video

Actin

Myosin

Actin

Myosin

Don’t confuse these terms!

MUSCLE FASCICLE: a group of muscle fibers, surrounded by perimysium.

MUSCLE FIBER: a single muscle cell

MYOFIBRIL: a long organelle inside a muscle fiber, contains actin and myosin myofilaments.

MYOFILAMENTS: these are proteins, and there are two types: actin (with troponin and tropomyosin) and myosin. The myofilament is the lowest level of organization that is composed of actin, troponin, and tropomyosin proteins.

Therefore, a myofilament is part of a myofibril, which is inside a muscle fiber, which is inside a muscle fascicle.

MECHANISM OF CONTRACTIONThe Sliding Filament Theory

Contraction results as the myosin heads of the thick filaments attach like hooks to the thin actin filaments at both ends of the sarcomere and pull the thin filaments toward the center of the sarcomere.

The myosin head is like a hook with a hinge. After a myosin head pivots at its hinge, it draws the actin closer, then lets go, springs up again to grab the actin filament again, pulls it closer, and it keeps repeating this until the entire actin filament has been drawn in as far as it can go.

Sarcomere Contraction The complete process of contraction of the sarcomere takes

only a fraction of a second. The actin and myosin filaments do not shorten; they

merely slide past each other. The energy required is ATP. This sliding filament mechanism begins whenever calcium

ions bind to the thin filament. Where does the calcium come from?

SARCOPLASMIC RETICULUM AND T TUBULES

Within the cytoplasm of all body cells is an endoplasmic reticulum.

The endoplasmic reticulum in muscle cells is called the SACROPLASMIC RETICULUM.

It surrounds each sarcomere like the sleeve of a loosely crocheted sweater.

Most of the “yarn fibers” of this “knit sweater” run longitudinally, but some run perpendicular to them and surround structures called T tubules.

Sarcoplasmic reticulum is in blue

T tubules are in yellow

Calcium is needed for muscle contraction The sarcoplasmic reticulum stores a lot of calcium

ions, which are released when the muscle is stimulated to contract.

The calcium diffuses through the sarcoplasmic reticulum to the actin filaments, where they trigger the sliding filament mechanism of contraction.

After the contraction, the calcium ions are pumped back into the sarcoplasmic reticulum for storage.

Calcium is needed for muscle contraction

ACTIVE TRANSPORT is required to return the calcium ions to the sarcoplasmic reticulum.

It also requires energy to make the myosin head cock back again, ready to spring onto the next binding site.

Therefore, ATP is used. ATP is used to return calcium to the sarcoplasmic

reticulum ATP is used to cock back the myosin heads

ATP is required for contraction ATP attaches to the myosin myofilaments

Provides energy for the movement of the cross bridges

ATP is required for muscle relaxation ATP releases part of its energy as heat.

That is why we get hot when we exercise When we are cold, we shiver (muscle contraction)

to warm up. In order for the mitochondria to produce enough ATP,

it needs oxygen and the sugars that are in storage.

For contraction to take place, you need two things: nerve signal and calcium

For skeletal muscle to contract, the synaptic knob of a neuron must first release a chemical called ACETYLCHOLINE onto the region where it sits on the muscle cell, known as the ENDPLATE.

Calcium is also needed for muscle contraction. The nerve signal is called an ACTION

POTENTIAL. It causes a release of calcium from the sarcoplasmic

reticulum, which causes contraction.

Muscle Contraction In a muscle fiber, an action potential results in

muscle contraction. How does this happen? The action potential continues to travel along the

sarcolemma (cell membrane of the muscle). Part of this electrical impulse breaks away from

the sarcolemma and travels down the T-tubules, while the rest of the electrical impulse continues longitudinally down the muscle cell to the next sarcomere and T-tubule.

T tubules are in yellow

T TUBULES T TUBULES (“T” stands for “transverse”)

are continuations of the sarcolemma (cell membrane) which invaginate to the deepest regions of the muscle cell.

Since the T tubules conduct the nerve impulse throughout the muscle cell, all the sarcomeres of that cell contract at the same time.

Muscle Contraction The action potential of the nerve goes down the T-

tubules and causes calcium to leak out of the sarcoplasmic reticulum.

The calcium causes the muscle fibers to contract. After a while, the calcium gets pumped back where

it came from, the muscle fibers relax, although it requires gravity or another muscle to pull the sarcomere back to its original length.

How does the calcium cause the muscle fibers to contract?

TROPOMYOSIN is a single long protein strand like a piece of yarn that winds around the actin filament.

• Tropomyosin blocks actin’s attachment site for the myosin head, so the myosin “hook” has nothing to grab onto, thus preventing contraction.

TROPONIN is a globular complex of three proteins, and is found in clumps around the tropomyosin protein.

• Troponin is the specific molecule that provides the calcium binding site on actin.

• Calcium binds to troponin and causes troponin to move a little, taking the tropomyosin thread with it, so the attachment sites on the actin molecule are now exposed. The myosin heads can now hook into the exposed sites on the actin myofilament.

Both troponin and tropomyosin cover the actin filament when the muscle is relaxed.

This is an illustration of an actin molecule. You can see the thready tropomyosin and the globular troponin proteins wrapping around the double-stranded actin.

When calcium binds to the globular troponin, it moves, taking the tropomyosin thread with it. This exposes the myosin binding site on the actin.

Calcium in muscle contraction When the muscle cell is stimulated to contract by an action

potential, calcium channels open in the sarcoplasmic reticulum and release calcium into the sarcoplasm.

Some of this calcium attaches to troponin, causing a conformational change that moves tropomyosin out of the way so that the myosin heads can attach to actin and produce muscle contraction.

When the calcium gets pumped back where it came from, the tropomyosin protein blocks the myosin head again so it can no longer get its hook into the actin filament, and the muscle will relax.

Rigor Mortis A new ATP molecule must bind to the myosin

before the cross-bridge can be release. When ATP is not available after a person dies, the cross-bridges that have formed are not released, causing muscle to become rigid (rigor mortis)

NOTE: Sarcomeres lengthen during muscle relaxation, but only if gravity or an opposing muscle pulls the sarcomere back to its original length.

Muscle Contraction http://www.youtube.com/watch?

v=CepeYFvqmk4

http://www.youtube.com/watch?v=WRxsOMenNQM&feature=related

http://www.youtube.com/watch?v=InIha7bCTjM&NR=1

Sequence of events The action potential reaches the cell membrane The action potential reaches the T-tubules The ion channels in the sarcoplasmic reticulum open Calcium ions move along their concentration gradient Actin forms cross-bridges to myosin The actin myofilaments move closer to each other,

causing contraction of the sarcomere. NOTE: A muscle fiber will not respond to a stimulus

until that stimulus reaches the threshold level.

Muscle Contraction

A muscle TWITCH is one single muscle fiber contraction.

It takes 1/20th of a second. How is it that I can pick up and hold a chair if the

fiber only contracts for 1/20th second? There are ten thousand fibers per muscle; each

one contracts at different intervals, so contraction is maintained, just like tug-of-war. One person in ten can drop the rope and get a better grip because the others are maintaining the tension.

Motor UnitsA MOTOR UNIT is a single neuron and all of

the muscle fibers on which it synapses.

If one neuron sends a signal, only its muscle fibers contract (the motor unit). This allows for strength variations in lifting a chair vs. an eraser. For full strength, all the motor units contract. For half strength, half of the motor units contract.

Motor Units

There are 3 motor units in this diagram; that allows for 3 different levels of contraction. The more motor units there are, the more precisely the muscle can respond.

Motor Units The action potential continues from one motor neuron

to the next motor neuron until the last neuron lands on its target cells; in this case, skeletal muscle fibers.

A single motor neuron and all the skeletal muscle fibers it iterates constitute a motor unit.

A muscle in your tongue may be innervated by many neurons to allow for precise movement. However, large thigh muscles may have only one neuron innervating thousands of muscle fibers, since precision is not necessary.

Motor Units A large motor unit is when one neuron supplies

many muscle fibers. An example is the muscles of the back. These areas will have fewer motor units present. Therefore, you get more strength, but less precision.

A small motor unit is when one neuron supplies few muscle fibers. Therefore, many motor units will be present in that muscle. An example is the tongue. That causes less strength but more precision.

Muscle Twitch Phases

A muscle twitch has three phases The lag phase is the time between the application of a

stimulus and the beginning of contraction. The contraction phase is the time of contraction. The relaxation phase is the time during which the

muscle relaxes.

The refractory period is the time between muscle twitches.

Refractory period

Force of Contraction The strength of muscle contraction can vary from weak to

strong. For example, the force generated by muscles to lift a feather is much less than the force required to lift a 25 pound weight.

The force of contraction produced by a muscle is increased in two ways:

Summation, which involves increasing the force of contraction of the muscle fibers within the muscle

Recruitment, which involves increasing the number of muscle fibers contracting

Summation The force of contraction of individual muscle fibers is increased by rapidly

stimulating them. Stimulus frequency is the number of times a motor neuron is stimulated per

second. When the stimulus frequency is low, there is time for complete relaxation of

muscle fibers between twitches. As stimulation frequency increases, there is not enough time between

contractions for muscles to completely relax. Thus, one contraction summates, or is added onto, a previous contraction.

As a result, the overall force of contraction increases. Tetanus is the condition in which a muscle remains contracted between

stimuli without relaxing.

TETANUS TOXIN A toxin caused by a certain bacteria can cause muscle to remain

contracted (in tetanus). It quickly results in death because the diaphragm and other

respiratory muscles cannot function properly, and the person suffocates.

The bacteria that make this toxin live deep in the soil and cannot survive in air. If you step on something that imbeds soil deeply into your tissues (like a rusty nail), you might contract the bacteria. You will need a tetanus vaccine before the toxins accumulate.

Recruitment In recruitment, the strength of contraction of the muscle is

increased by increasing the number of motor units stimulated. When only a few motor units are stimulated, a small force of

contraction is produced, because only a small number of muscle fibers are contracting.

As the number of motor units stimulated increases, more muscle fibers are stimulated to contract, and the force of contraction increases.

Maximum force of contraction is produced in a given muscle when all the motor units of that muscle are stimulated, or recruited.

Types of Muscle ContractionsMuscle contractions are classified as either isometric or isotonic. Most muscle contractions are a combination.

Isometric (equal distance) tension increases during contraction length of the muscle does not change Example is when you push against a wall or try to pick up an object

that is too heavy to lift

Isotonic (equal tension) tension is generally constant during contraction

Although in one type of isotonic contraction, the tension increases Length of the muscle changes (either increases or decreases). Example is when you lift a weight.

Concentric and Eccentric Contractions

Two types of isotonic contractions: CONCENTRIC CONTRACTIONS are isotonic contractions

in which the muscle tension increases as the muscle shortens. Most movements performed by muscle contractions are of this type.

ECCENTRIC CONTRACTIONS are isotonic contractions in which tension is maintained as the muscle lengthens. An example is when a person lets down a heavy weight slowly. Substantial force is produced in the muscles and injuries can occur from repetitive eccentric contractions, such as in the hamstring muscles when a person runs downhill.

Muscle Tone Even when muscles are relaxed, some of their fibers

are still contracting, giving the muscle some tone. Therefore, the normal state of a muscle, with some

contraction, is called muscle tone. This is important in posture so you can stand upright but mostly relaxed.

Muscle tone refers to the constant tension produced by muscles of the body over long periods of time. It is responsible for keeping the back and legs straight, the head held in an upright position, and the abdomen from bulging. it declines during REM sleep.

Muscle Tone Hypertonia

Can present clinically as either spasticity or rigidity

Hypotonia Seen in lower motor neuron diseases Can present clinically as muscle flaccidity, where

the limbs appear floppy, stretch reflex responses are decreased, and the limb’s resistance to passive movement is also decreased.

Muscle Spasticity Spasticity is a feature of altered skeletal muscle performance in

muscle tone involving hypertonia, which is also referred to as an unusual "tightness" of muscles. Clinically spasticity is defined as velocity dependent resistance to stretch, where a lack of inhibition from the CNS results in excessive contraction of the muscles.

Passively moving an elbow quickly will elicit increased muscle tone, but passively moving elbow slowly may not elicit increased muscle tone

It mostly occurs in disorders of the central nervous system (CNS) impacting the upper motor neuron in the form of a lesion, but it can also present in various types of multiple sclerosis, which are autoimmune conditions.

Muscle Spasticity Precise cause aside, whenever there is a loss of muscle tone

inhibition from the brain to the spinal cord such that muscles become overactive, this loss of inhibitory control can cause an ongoing level of contraction, with decreased ability for the affected individual to volitionally control the muscle contraction, and increased resistance felt on passive stretch.

There is a difference in cause of two of the most common spasticity conditions, spastic diplegia and multiple sclerosis.

In spastic diplegia, the upper motor neuron lesion arises often as a result of neonatal asphyxia (lack of oxygen in a newborn), while in conditions like multiple sclerosis, spasticity is from autoimmune destruction of the myelin sheaths around nerve endings.

Muscle Spasticity A defining feature of spasticity is that the

increased resistance to passive stretch is velocity-dependent.

There is a velocity-dependent increase in tonic stretch reflexes (muscle tone) with exaggerated tendon jerks, resulting from hyper-excitability of the stretch reflex.

Muscle Spasticity Causes include

Cerebral palsy Spastic diplegia (a form of Cerebral palsy)

Multiple sclerosis Spinal cord injury Stroke

Muscle Rigidity Unlike spasticity, rigidity is velocity-

independent resistance to passive stretch. There is uniform increased tone whether the

elbow is passively moved quickly or slowly.

Muscle Clonus Clonus (from the Greek for "violent, confused motion") is a series

of involuntary muscular contractions and relaxations. Clonus is a sign of certain neurological conditions, and is

particularly associated with upper motor neuron lesions such as in stroke, multiple sclerosis, spinal cord damage.

Clonus causes large motions that are usually initiated by a reflex. Clonus is most common in the ankles, where it is tested by rapidly

flexing the foot upward (dorsiflexion). It can also be tested in the knees by rapidly pushing the patella

(knee cap), towards the toes. Only sustained clonus (5 beats or more) is considered abnormal.

Muscle Fasciculations These are small, local, involuntary muscle

contraction and relaxation visible under the skin arising from the spontaneous discharge of a bundle of skeletal muscle fibers (muscle fascicle).

Fasciculations have a variety of causes, the majority of which are benign, but can also be due to disease of the lower motor neurons.

Muscle Fasciculations Benign causes of fasciculations include:

Magnesium deficiency Diarrhea Overexertion Inadequate intake from diet (almonds are a good

source of magnesium)

Dehydration Fatigue

Muscle Fasciculations They can also be caused by long-term use of:

Benadryl (antihistamine) Dramamine (for nausea and motion sickness). Caffeine Sudafed Asthma medicines ADD medicines

Muscle Fasciculations More serious conditions causing

fasciculations include Fibromyalgia Myasthenia Gravis Lyme Disease Rabies

Hyperreflexia The most common cause of exaggerated reflexes

is spinal cord injuries (upper motor neuron diseases).

Other causes include Medication Stimulants Hyperthyroidism Electrolyte imbalance Severe brain trauma.

Hyporeflexia This means diminished or absent reflexes. The most common cause is lower motor

neuron diseases.

Muscle Contractures Muscle contractures can occur from paralysis,

muscular atrophy, muscular dystrophy, immobilization from a cast, and chronic spastic conditions like cerebral palsy.

Fundamentally, the muscle and its tendons shorten, resulting in reduced flexibility.

Muscle contractures in tendons are caused from the fibrinogen leaking out of the fibroblasts, which turn the elastic fibers into inelastic fibers.

Most treatments involve surgery, so physical therapy efforts focus on prevention of contractures.

Energy Requirements of Muscle What fuel does a car use?

Gasoline What fuel does a candle use?

Wax What fuel do humans use?

Oxygen? NO

Sugars? NO

ATP YES

ATP Where do we get ATP? We can make a little ATP in the cytoplasm of our cells, but not

enough to live on. Most of our ATP is made by the mitochondria inside our cells. Mitochondria are like little protozoa (animals) that live in our

cells. Each cell has hundreds of them. Muscle cells have thousands of them.

What is their fuel? Oxygen and glucose

THAT is why we need to inhale oxygen and consume sugars….to feed our mitochondria so they can make ATP for us!

Energy Requirements For Muscle Contraction In order for the muscle mitochondria to produce

enough ATP, they need oxygen (for their own aerobic respiration) and sugars that are in storage.

Mitochondria can only perform aerobic respiration. What can we do to make ATP if our muscle cells run

out of oxygen? Start performing anaerobic respiration. We can do this ourselves in the cytoplasm of our cells.

Making ATP by Aerobic RespirationAerobic respiration Takes place in the mitochondria Requires oxygen Breaks down glucose to produce ATP Waste products are CO2 and H2O (we exhale them) The good thing about making ATP from our mitochondria

is that we can make a LOT of it. The bad things are that it takes longer to make it, and it

requires oxygen, and a muscle cell may have used up all the oxygen during a sprinting run.

Making ATP by Anaerobic RespirationAnaerobic respiration Takes place in the cytoplasm Does not require oxygen Breaks down glucose to produce ATP Waste product is lactic acid The good thing about making ATP this way is that we

can make it FAST. The bad thing is that it does not make much ATP,

and we deplete the reserves quickly.

Lactic Acid The waste product of aerobic respiration is carbon

dioxide and water. These are not a problem…we eliminate them by exhaling.

The waste product of anaerobic respiration is lactic acid, which can irritate muscle fibers, causing muscle pain (stitch in your side) and muscle cramps.

We deactivate lactic acid by adding oxygen to it. Therefore, breathing heavily adds the oxygen to our system to deactivate lactic acid, and the muscle pains go away.

ATP and Creatine Phosphate What do we do when we run out of ATP? Muscle fibers cannot stockpile ATP in preparation for future

periods of activity. However, they can store another high energy molecule called

creatinine phosphate. Creatine phosphate is made from the excess ATP that we

accumulate when we are resting. During short periods of intense exercise, the small reserves

of ATP existing in a cell are used first. Then creatinine phosphate is broken down to produce ATP.

Aerobic vs. Anaerobic Respiration When do we use aerobic respiration?

Resting (can breathe easily) Running marathons (can breathe easily on long runs)

Marathon runners want to make sure there will be enough readily available energy for the muscles, so they eat a lot of carbohydrates over a two-day period before the marathon. That’s why they load up on pasta before a marathon.

When do we use anaerobic respiration? Sprint running (can’t talk while sprinting!)

Aerobic vs. Anaerobic Respiration

Why does sprinting require anaerobic respiration? We use up all of the ATP faster than we can make it.

When we run out of ATP, we break down creatine phosphate to make more ATP.

When we run out of glucose, or too much lactic acid is built up, we have to stop and rest.

Anaerobic metabolism is ultimately limited by depletion of glucose and buildup of lactic acid within the muscle fiber.

Sprint Runners Why do sprint runners tire out during the last part of a

fast run? Sprinting is an anaerobic activity…the oxygen

requirement is quickly exceeded, so the muscle has to use anaerobic respiration to continue to contract. This requires a lot of glucose and also results in a buildup of lactic acid.

Once the sprint-runner has used up the available glucose, or has produced too much lactic acid, the muscles fatigue.

Oxygen Debt Anaerobic respiration produces lactic acid, which

causes the painful cramps because it creates an oxygen debt.

The amount of oxygen needed to replenish the supply following aerobic demand is called the oxygen debt.

When you continue to breathe heavily after exercising, it means you have an oxygen debt.

Muscles can do without oxygen for a while pretty well, unlike the brain.

To pay back a minor oxygen debt, you just have to breathe heavily for a while.

Oxygen Debt

This heavy breathing brings in oxygen, which is used to convert lactic acid to glucose, replenish the depleted ATP and creatinine phosphate stores in the muscle fibers, and to replenish oxygen stores in the lung, blood, and muscles.

After the oxygen debt has been paid back, breathing returns to normal.

People who are in good physical condition can carry out both aerobic and anaerobic activities efficiently, and do not suffer from an oxygen debt for very long.

EXERCISE There are many physiological benefits of

exercise:

1. Improved muscular strength, endurance, flexibility

2. Improved cardio-respiratory endurance

3. Increased bone density and strength

4. Relief from depression

5. Increased HDLs

Hypertrophy Weight training and other exercises can cause muscles to

hypertrophy ( enlarge). This occurs as more myofilaments and myofibrils are produced inside a myofiber, causing them to enlarge. The number of mitochondria also increases, causing additional enlargement.

However, you don’t grow new muscle cells. The number of cells in a skeletal muscle remains relatively constant following birth.

Hypertrophy can happen in two ways: Increase in number of fibers inside a muscle cell Increase in size of individual fibers

Muscle hypertrophy is greater in males due to the hormone testosterone.

Hypertrophy A professional athlete may have many muscles that exhibit

hypertrophy. Eating protein does not automatically increase muscle. The

average person only needs one ounce of protein a day, two if you work out.

Two ounces is like one mini hamburger. Most people eat too much meat.

Fun Fact: -You use 200 muscles to take one step.

Atrophy Lack of use causes muscle ATROPHY. This happens quickly.

Astronauts can lose 40% of their muscle in two weeks! It is regained quickly, too.

Atrophy is a decrease in muscle size because of the decrease in myofilaments within muscle fiber.

Severe atrophy involves the permanent loss of skeletal muscle fiber and the replacement of those fibers by connective tissue.

Damage to the nervous system, or a severed motor nerve can cause atrophy. The muscle becomes flaccid (having no tone) .

Casting a broken limb also leads to temporary atrophy.

Muscular Dystrophy

This refers to a group of inherited muscle disorders in which skeletal, cardiac, and smooth muscle tissue degenerates and the person experiences progressive weakness and other symptoms, including heart problems.

The disorders are characterized by the progressive degeneration of muscle fibers leading to atrophy and their eventual replacement by fat and other connective tissue.

Muscular Dystrophy

MUSCULAR DYSTROPHY

This is a genetic lack of a protein called DISTROPHIN. It causes the muscle tissue to harden, inhibiting contraction, causing progressive paralysis.

Duchenne muscular dystrophy is more common in males.

Muscle Problems Tendonitis is an inflammation of the tendon or its

attachment point. It usually occurs in athletes who overuse the muscle to which the tendon is attached.

A strain is a tear in a muscle. Remember, a sprain is a tear in a ligament.

A muscle strain will heal faster than a torn ligament because muscles have good blood supply and ligaments do not.

Treatment for Injuries: RICE Rest Ice

20 minutes on, 20 minutes off Ice pack or frozen bag of peas!

Compression Ace wrap from distal to proximal Don’t leave any openings while wrapping

Elevation Above the heart

Treatment for Injuries

Ice for the first 72 hours (NO heat!) Anti-inflammatory medicines

Ibuprofin, 600 mg TID (3x a day) Over the counter (OTC) pills are 200 mg

Heat and massage as needed after third day. Can try a muscle stimulator too…works pretty

well!

Muscle Spasms Muscle spasms/cramps are sudden and involuntary muscle

contractions. They are painful, spastic contractions that are usually caused from overexertion. Lactic acid builds up and irritates the overused muscles, causing inflammation. If the muscle remains in spasm for longer than a few minutes, might need heat and massage to increase circulation.

Avoid spasms by stretching before and after activities. For people with frequent low back spasms throughout the day, a

portable muscle stimulator that clips to the belt will help a great deal.

Muscle stimulator to relieve muscle spasms or to prevent muscle atrophy in casts$59

http://www.medicalproductsonline.org/meprondi75mu.html

$3.50

http://www.medicalproductsonline.org/recaclel10pa.html

Fibromyalgia (muscle and tissue pain)

Common disorder in adults, especially women Painful muscles, debilitating fatigue, sleep

disturbance, and joint stiffness Many trigger points: painful lumps in muscles Treatment includes anti-inflammatory medicines,

physical therapy, acupuncture, and exercise. Muscle stimulators help

Ganglion Cysts Ganglion cysts arise as outpouchings from fluid

filled areas such as the fluid around tendon sheaths.

When the fluid, called synovial fluid, leaks out from these spaces, it can become a cystic structure.

Treatment is to drain the fluid with a needle, but they frequently grow back.

Then you do a surgery to scoop out the whole cyst, find the stalk and tie it off.

• Ganglion cyst

Baker’s Cyst A Baker's Cyst, or popliteal cyst, is a collection of

fluid in the back of the knee joint. A Baker's cyst is usually a symptom of another

problem, or it may be an incidental finding with no significant meaning.

Most often in adults the Baker's cyst is found in conditions where there is chronic swelling or fluid accumulation in the knee joint.

These conditions include knee arthritis, meniscus injuries, and ligamentous injuries.

Baker’s Cyst

Treatment of a Baker's cyst that is the result of a problem within the knee consists of treating the underlying problem. These treatments may include anti-inflammatory medications and cortisone injections.

The cyst can be drained with a needle, but the fluid can be jelly-like and difficult to remove.

If conservative treatments fail to correct the cyst, an operation can be done to excise the cyst.

• Baker’s Cyst

Rotator Cuff Injury http://www.youtube.com/watch?v=-tx2SqWz3BY

How do rotator cuff injuries occur? https://www.youtube.com/watch?v=t6FCBBijROo

What is an MRI? https://www.youtube.com/watch?v=H0adTNhzGxU

How does a CT scan work? http://www.youtube.com/watch?v=81PeTqmtzjk

110

AGING With aging, fibrous connective tissue

replaces some muscle fibers, causing decreased strength.

As people age, the number of muscle fibers decreases, and new ones cannot be added.

FUN FACTS ABOUT STRENGTH

The strongest humans can lift about 3 times their own body weight, but the average gorilla can lift 10 times its own body weight! Gorillas can lift 4,600 pounds.

But the strongest creature is the ant. If you had the strength of an ant, you could lift over your head and carry 6,600 pounds.

The flea, however, can jump up to 200 times its own height. This is equivalent to a man jumping the Empire State Building in New York.

Elephants are the only animals that cannot jump!