Sign In | Subscribe

Enter your Sign on user name and password.

Forgot password?
  • Follow us on:
Start learning today, and be successful in your academic & professional career. Start Today!
Loading video...
This is a quick preview of the lesson. For full access, please Log In or Sign up.
For more information, please see full course syllabus of Anatomy & Physiology
  • Discussion

  • Study Guides

  • Download Lecture Slides

  • Table of Contents

  • Transcription

  • Related Books

Lecture Comments (10)

2 answers

Last reply by: Jessie Carrillo
Thu Oct 27, 2016 9:22 PM

Post by Jessie Carrillo on October 27, 2016

any information in helping to memorize the muscles of the body?

1 answer

Last reply by: Bryan Cardella
Mon Mar 23, 2015 4:13 PM

Post by Julia Collings on March 23, 2015

I am unable to access these videos. please help as ai have signed up now to aid revision for upcoming tests :)

1 answer

Last reply by: Bryan Cardella
Fri Mar 13, 2015 2:40 PM

Post by Andy Pace on March 12, 2015

Was wondering if there is a short answer for this:
How is energy expenditure related to the energy systems in the body?
Does one system expend more energy than the others?
Thanks for any help

1 answer

Last reply by: Bryan Cardella
Tue Jun 3, 2014 1:46 PM

Post by Andy Pace on June 3, 2014

What factors affect muscle force production?

0 answers

Post by John Wadsworth on March 5, 2014

great chicken-attempting-to-fly demonstration

Muscular System

  • The function of muscles includes movement, maintaining body position, support of soft tissues, regulating entrances and exits of the body, and maintaining body temperature
  • The 3 types of muscle cells (tissues) includes skeletal (striated), smooth, and cardiac muscle
  • Skeletal muscle anatomy involves these terms: fascia, epimysium, fascicles, perimysium, muscle fibers, endomysium, myofibrils, and sarcomeres
  • Sarcomeres are made of groups of myosin, actin, troponin, and tropomyosin
  • The Sliding Filament Theory describes how myosin (thick) filaments move actin (thin) filaments closer together to contract a myofibril
  • Acetylcholine, ATP and Calcium are involved in contracting a muscle
  • Acetylcholinesterase and ATP are needed to relax a muscle
  • Lactic acid forms in muscle tissue when not enough oxygen is available for the energy demands of that tissue
  • Creatine phosphate helps quickly regenerate ATP in a muscle fiber
  • Fast (white) and slow (red) twitch muscle fibers are found in the human body
  • Muscle names in the body are coined by some combination of their function, location, size, and/or orientation
  • Muscles of the head and face include the epicranius, zygomaticus, buccinator, and masseter
  • Muscles of the torso include the deltoid, trapezius, latissimus dorsi, and rectus abdominus
  • Arm muscles include the biceps brachii, triceps brachii, and brachioradialis
  • Leg muscles include the gluteus maximus, rectus femoris, and gastrocnemius
  • Some muscle conditions/disorders are muscular dystrophy, hernia, tetanus, and compartment syndrome
  • Did you know…
    • Q: Are any smooth muscles controlled voluntarily?
    • A: Smooth muscles are defined as being involuntary. They are found in your skin, lining of the gastrointestinal tract, and in blood vessels. However, some skeletal muscles are controlled involuntarily. One example is the muscles associated with breathing. You don’t have to think consciously about inhaling/exhaling, it happens automatically. Now that you’re reading about breathing, you probably just thought about it!

Muscular System

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  • Intro 0:00
  • Functions of Muscles 0:06
    • Movement
    • Maintaining Body Position
    • Support of Soft Tissues
    • Regulating Entrances / Exits
    • Maintaining Body Temperature
  • 3 Major Types of Muscle Cells (Fibers) 2:58
    • Skeletal (Striated)
    • Smooth
    • Cardiac
  • Skeletal Muscle Anatomy 5:49
    • Fascia
    • Epimysium
    • Fascicles
    • Perimysium
    • Muscle Fibers
    • Endomysium
    • Myofibrils
    • Sarcomeres
  • Skeletal Muscle Anatomy Images 9:32
  • Sarcomere Structure 12:33
    • Myosin
    • Actin
    • Z Line
    • A Band
    • I Band
    • M Line
    • Another Depiction of Sarcomere Structure
  • Sliding Filament Theory 15:11
    • Explains How Sarcomeres Contract
    • Tropomyosin
    • Troponin
    • Calcium Binds to Troponin, Causing It to Shift Tropomyosin
    • Image Examples
    • Myosin Heads Dock and Make a Power Stroke
    • Actin Filaments Are Pulled Together
    • Myosin Heads Let Go of Actin
    • They 'Re-Cock' Back into Position for Another Docking
  • Relaxation of Muscles 21:11
    • Ending Stimulation at the Neuromuscular Junction
    • Getting Calcium Ions Back Into the Sarcophasmic Reticulum
    • ATP Availability
    • Rigor Mortis
  • More on Muscles 26:22
    • Oxygen Debt
    • Lactic Acid
    • Creatine Phosphate
    • Fast vs. Slow Twitch Fibers
  • Muscle Names 32:24
    • 4 Characteristics: Function, Location, Size, Orientation
    • Examples
  • Major Muscles 33:51
    • Head
    • Torso
    • Arms
    • Legs
  • Muscular Disorders 45:02
    • Muscular Dystrophy
    • Carpel Tunnel
    • Hernia
    • Ischemia
    • Botulism
    • Polio
    • Tetanus
    • Rotator Buff Injury
    • Mitochondrial Diseases
    • Compartment Syndrome
    • Fibrodysplasia Ossificans Progressiva

Transcription: Muscular System

Hi and welcome back to

This is the lesson on the muscular system.0002

There are many functions of muscles the most obvious one is movement.0004

It is not just movement of the body as a whole but all the movement within the body is regulated by the muscles something a simple as blood flow.0010

Within your arteries there are very important muscles for regulating how thin or thick those blood vessels are and0021

that helps distribute the right amount of blood to the particular places in the body that need a slight adjustment.0030

Within the body muscles are very important, the ones that you cannot consciously control.0036

For instance, muscles control whether or not my hair is standing straight up or my pores are closed or they are relaxed like they are now.0041

Those are muscles that we do not think about because we do not have to think about it consciously to make it work.0049

There are voluntary muscles also known as skeletal muscles and this would fall under smooth or cardiac muscles.0057

We will talk more about that in the future.0068

Maintaining body position, just sitting I have bunch of muscles that are contracted and relaxed.0071

If I adjust my position then I am changing which muscles are relaxed and contracted.0079

Supportive soft tissues, if you think about the abdominal muscles even if you do not have a 6 pack,0084

having all the muscles right here is the next best thing to have bones there.0093

If we had bones there it would be a little different in terms of how we move this part of this chest but supportive soft tissues,0099

having muscles here adjacent to the most fragile vital organs of the intestine variety is very important.0105

Regulating entrances and exits.0115

Not just the mouth but the connection between the esophagus and the stomach.0118

At the bottom of the tube that gets food to the stomach you have the lower esophageal sphincter.0123

Sphincter is a round muscular doorway and that helps regulate food going to the stomach.0128

There is also a sphincter on the bottom of the stomach that helps regulate how much food0135

is going to the small intestine for further break down and absorption of nutrients.0141

Another one is the anal sphincter, that regulates when or where you are going to defecate.0146

Maintaining body temperature.0152

Shivering is something that is going to help you not freeze to death.0155

Shivering is a bunch of quick contractions and relaxations that you do not have conscious control over but it is important0163

because it will raise you body temperature a bit by having all of that muscular movement.0170

The 3 major types of muscle cells or muscles fibers0178

You can call every individual muscle cell fiber that has a bunch of protein fibers jam packed in it.0182

We can refer to the major muscles in the body as being skeletal, smooth, and cardiac.0190

The cells within each of those can be called skeletal, smooth, or cardiac.0196

This image here this is skeletal or striated muscles.0201

Striations are these little lines.0207

If you look carefully, this is a skeletal muscle fiber and you can see that when you look at each one of them there0210

are these tiny lines that are perpendicular to the orientation of the fiber.0218

These little lines you can call striations and we will get into that more in the future.0223

These blue things here they are nuclei.0230

Each one is an individual nucleus and it is very typical for muscles to be multi nucleated or having more than one nucleus in a single cell.0234

There is a lot going on, having some additional nuclei to help coordinate all of those muscular movements.0242

This picture here is smooth muscles.0250

It looks smooth to the touch almost like if you touch it, it would not be bumpy.0253

It would be smooth.0258

Those are involuntary.0259

You do not have conscious control over smooth muscles.0262

Like I have mentioned before, the muscles that are inside of the artery, the arrector pili muscle of the skin, the muscles in the organs of the body.0264

You cannot consciously contract your stomach, small intestine, it happens by your brain regulating it but not your conscious brain.0270

It is good to have not to think about those things.0283

Smooth muscle is a little bit different in structure.0287

These are involuntary muscles.0290

Cardiac is found in one place of the body it is the heart muscles.0293

The muscles fiber of the heart also is not a voluntary thing.0298

You can voluntary do thing to elevate your heart rate but your heart rate is going to be adjusted based on your body’s need for blood.0303

What is this mean?0312

It means intercoagulated disk.0314

This here is and itercoagulated disk, here is one cardiac muscle.0317

You will see them connect looks a little bit different than the skeletal or striated muscle.0322

Also a classic look at cardiac muscle histology looking at this microscope images, you will see little spaces.0331

Those little spaces help facilitate the electric flow through out those cardiac muscle fibers to initiate heart beats.0340

When we look at the average skeletal muscles and the reason why it is called that is because it is attached to bone.0346

There are major terms that you need to be familiar with.0356

Number 1 here that is a bone.0358

Number 8 this is not a ligament because it is muscle attached to bone not bone attached to bone, in this case we will call this a tendon.0361

That is one of many forms of a connective tissue.0373

When we look at the muscle body as a whole, and there is a cross section here that we could see into the inside of it,0377

fascia is the term for the wrapping around the muscle.0383

Fascia is the muscle as the casing is to sausage.0388

It is kind of a weird example but that clear casing of sausages is like how fascia is to muscle.0393

It is a connective tissue that is keeping it all wrapped together as one unit.0399

Just underneath that you are going to see connective tissue called epimysium.0406

Epi means the outermost typically.0411

All of these white stuff around the outside that is epimysium.0415

Epimysium is a connective tissue that surrounding all of these little bundles called fascicles.0424

Number 6 is labeling 1 fascicle.0430

Here is a fascicle.0434

Basically fascicles are bundles of muscle fibers.0436

Each one of these little red tubular units that we are seeing a cross section of these are each of the muscle cells or muscle fibers.0445

What is separating fascicles from each other within a muscle?0458

That is called a perimysium.0462

The perimysium is the intermediate connective tissue.0464

Here there will be perimysium.0469

It is separating fascicles from each other.0478

As I mentioned, fascicles are contained within each muscle fiber.0480

The same thing as muscle cells.0486

Number 4 is labeling 1 muscle fiber.0488

It is like one of those antennas where you pull out a smaller tube from the bigger tube.0495

Here is 1 muscle fiber being pulled out of a fascicle, being pulled out of a muscle as a whole.0502

The last connective tissue that I want to tell you about is endomysium.0510

This little white area that is separating the individual muscle fibers from each other within one fascicle, that is endomysium.0515

Endo typically means inner.0522

That is the inner connective tissue in here.0525

Myofibrils are groups of protein fibers that are found within every muscle fiber.0527

We are getting tinier and tinier here.0539

This is important because in one muscle fiber, you can have billions of protein fibers.0542

It is amazing to think about having all of those protein fibers arranged in individual units is important.0551

That is what myofibrils do.0557

Sarcomeres you cannot see them here but they are individual units that are within a myofibril.0560

Here is a different view of what we are long on the previous slides.0569

This is the same image.0577

Here is a muscle fiber and this is a myofibril.0579

This whole thing, one muscle cell and here is all the myofibrils being pulled out.0585

If we zoom in to one myofibril, here is a super close up, the sarcomere is from here to here.0591

You can see it is tiny but it is one sarcomere.0599

It is from this border to this border.0602

Here is another sarcomere from this border to the next one.0604

This border is often time depicted as a zig zag line and it is also called the Z line.0608

I remember the term Z line because it is usually depicted as zig zag in a lot of textbook images.0615

You will see one a little bit in this presentation.0622

Sarcomere from Z line to Z line.0625

What is inside of the sarcomere?0629

Many different types of protein fibers that help contract and relax muscle as a whole.0631

Here is a look at them.0637

See this in this center, I am going to label them red.0639

I am not going to color the whole thing but all of these are called myosin.0644

There is your myosin filaments and then the thinner ones that are connected these are called actin filaments.0649

You could see that if you look further on the other sarcomeres it is a very repetitive system.0662

Here is a zoom in of what we are looking at here.0672

If you zoom in to that blue set of actin filaments that are all together, up close you can see that it is this little spheres.0676

Each one of these spheres is a unit of actin.0684

You could see it is arranged in a spiral looking shape similar to DNA and there are couple of other proteins on top of that.0687

That are very tiny.0697

Troponin and this strand called tropomyosin.0698

We will get into what the functions of those are a little bit later.0703

Here is another depiction of the myosin filaments.0707

This little clubs often times called the myosin heads and when the myosin heads connect to actin they call it a cross bridge.0711

Basically, we are going to the steps at a moment.0722

It is all about myosin connecting to actin and moving it in.0725

When you move the actin in closer and closer, that causes muscles to be contracted.0730

If I contract my bicep, at a microscopic level you have thousands of these little activities that brings the actin closer to myosin.0736

That is called the sliding filament theory that explains how muscles function.0747

Sarcomere structure.0752

As I have mentioned a second ago, myosin is the larger filament, and here myosin is depicted as blue, they are thicker.0755

Actin is being depicted as red ones, those are the smaller filaments.0763

Here is that term Z line.0769

Imagine the Z line as zig zag.0773

That one is a sarcomere.0775

Here is an actual micrograph, this is an actual picture taking with a microscope.0779

This is computer generated.0784

Z lines that is the border of the sarcomere.0787

A band is basically the width of myosin.0789

A trick to remember that is the A band is darker and thicker.0796

The A band is that length of myosin.0811

I band is the length of the actin that is not overlapping with the myosin.0815

You can think of I band as being light and thinner.0829

You could remember that is the portion of actin filaments there within sarcomeres.0842

The M line is simply what is keeping the myosin together, what is anchoring the myosin in that immovable area and allowing to pull actin.0848

It is that M line, that blue line I just drew is in the H zone within the A band.0863

That is a sarcomere.0869

Here is another depiction of it.0872

You can see that up top, the Z line are farther away and down bottom since we have slight contraction it is farther in.0877

You can see that the difference between these 2 pictures is that there is a shorter sarcomere.0886

When a muscle contracts, every sarcomere within it has gotten less wide because the myosin has pulled in the actin0894

and that microscopic movement has lead to the microscopic movement of the muscle.0903

The sliding filament theory explains in detail how the sarcomere actually contracts.0909

As I have said before, if we look closer at the filaments there are more proteins.0917

Tropomyosin tends to be strand looking.0922

You will see tropomyosin looking like this and let us say that actin is in red.0928

We have all of these red units and they should be the same size.0939

In red is actin and in blue is the tropomyosin.0949

I am going to show you that same image on the next slide to remind you of what it looks like.0954

Troponin is more a globular looking protein.0959

I will write this in green ovals.0964

What happens is when you want to contract a muscle, you have neurotransmitters from the end of the axon and that will make more sense when we cover the nervous system in future lessons.0969

If the end of the neuron, the end of the bunch of nerves coming to a muscle, you have a neurotransmitter, a sigma molecule.0982

In this case it is acetylcholine.0991

It stimulates the muscle to contract.0993

The acetylcholine docks on the surface of the muscle which is called the sarcolema.0995

That in turn unleashes a bunch of calcium ions.1000

You have calcium reserves rather not just in bone.1004

Calcium is extremely important for muscle function.1008

There is this reserve like a giant dam, a giant reservoir of calcium.1012

It is called the sarcoplasmic reticulum.1019

If you take basic biology, the sarcoplasmic reticulum is like the endoplasmic reticulum or ER of the cell that is modified for muscles purposes.1021

The sarcoplasmic reticulum is the ER and within those membranes is fold you have a huge reserve of calcium.1031

Once the neurotransmitter from the nervous system docks, the flag gates open and calcium is dumped into the myofibrils.1040

All those units in a muscle that have the proteins.1047

Calcium I am going to use yellow to depict what calcium is.1051

Calcium is little charged ions, they dock on troponin.1056

What happens is once calcium binds to troponin it shifts.1065

It moves and causes a shift in tropomyosin because if you think about a troponin, it is directly attached to these blue strands that are wrapped around actin.1070

If troponin moves, it pulls on tropomyosin.1082

Once tropomyosin shifts, it exposes these areas on actin that are called binding sites.1085

A lot of textbooks make it look like the binding sites like a pimiento on the olive of actin.1093

That is a funny way to think of it.1100

Once tropomyosin shifts, the little pimiento, the binding site is exposed on actin and that allows myosin to connect to it.1102

We will look to that at the next slide.1112

Here we go.1114

You can see tropomyosin here is covering all those binding sites.1117

Once calcium binds to troponin, it moves that and tropomyosin is all the way and then these guys, the heads of myosin can attach.1123

They can do what is called the power stroke which is when you are getting down to business in terms of contracting a muscle.1135

Once the actin binding sites are exposed, you can see that myosin heads dock and they make a power stroke.1141

On the myosin heads you have parts of ATP.1151

It is not connected as ATP.1158

If you are not familiar with that term, it is an energy molecule that is very common in cells.1160

It is made up of 2 pieces.1165

ADP adenosinedyphosphate and phosphate.1167

Imagine my hands are the myosin heads, it may dock on actin they do call the power strokes.1170

Imagine I am docking on actin and when I go like this I am pulling in actin.1178

Visibly pulling it closer, making those Z lines come closer together.1185

Actin filaments are pulled together and then once you have done the power stroke to let go1189

and have it come back in position and go back, you need to have a fresh ATP molecule power it to take it off.1195

In order to take off that head that is made of power stroke, take it off of actin you need ATP.1206

You need a fresh energy molecule and then took that back in position.1213

Or I say recock back into position for another docking.1217

The ATP, the energy supply by it, by breaking apart, it gets it back into position.1221

Imagine that happening thousands of times in a second, it is amazing to think about this happening1227

but it makes sense because every power stroke is going to shorten a sarcomere by .5%.1234

Imagine how small a sarcomere is.1244

One power stroke pulling in of actin by myosin it does not even adjusted by 1%.1246

You have that attached, power stroke come off, re cock it, it is doing that just to do that simple contraction.1252

Just to do contraction of muscles.1258

There is a lot of going on to power that contraction and make that filament slide together.1263

How do you relax that muscle?1270

This is the opposite of contraction.1274

Relaxation is a passive process.1276

I have just told you about contraction of muscle, that is very active.1279

We needed this domino effect, a neurotransmitter making calcium come out to the muscle fibers, myofibrils more specifically attaching to this protein.1282

Relaxation of a muscle is just once does particular dominoes are no longer falling, relaxation can happen.1295

Some of the dominoes that are required to make contraction happen, one of them is the neurotransmitter.1304

If you end stimulation at the neuromuscular junction, that is what we are seeing here.1311

Number 1 is showing you the terminal end of an axon, the end of the neuron that is going to stimulate this muscle.1317

Here this membrane, the purple one, that is the surface of the muscle you can call the sarcolema.1323

This whole thing here is the neuromuscular junctions that is connecting your nervous system to your muscular system.1332

These little pinkish looking dots they are called synaptic vesicles.1338

Number 3 this is equal to synaptic vesicles.1344

They each contain neurotransmitters in this case would be acetylcholine.1354

To get the whole process started, those end up doing exocytosis.1359

They fuse with the edge here and dump those transmitters out into the space called the synapse.1364

You have to get these neurotransmitters to stop docking if you want to stop contracting a muscle.1370

That is the first thing that used to happen.1380

If we are talking acetylcholine with making muscles get stimulated, there is an enzyme that can be in the synapse to break down the neurotransmitter.1382

It is called acetyl cholinesterase.1392

In the side note, there is a pesticide that works by inhibiting is acetyl cholinesterase.1394

The enzyme that is supposed to get rid of all these green stimulators, if you let that enzyme work then we you sprayed it on an insect,1407

Let us say that with this insect that I am making motion with my legs, all of a sudden I am going to prolong the contraction and I am going to twitch to death.1415

I can no longer relax muscles and then re contract them if you are not allowing the break down or getting rid of these neurotransmitter to stimulate muscles.1425

Remember that calcium is released from a reserve down here called the sarcoplasmic reticulum.1435

If you get the calcium ions back into the sarcoplasmic reticulum, into their reservoir, that is another key point, you got to get the calcium out of the muscles.1443

Also, ATP is a key to relaxing muscles because remember when the myosin heads attach to actin1453

and it did a power stroke, the key of getting them off of actin is ATP.1461

If there is no ATP left in the muscle, you are not going to be able to let myosin off of that and let it go1467

and you have to let go to let the Z lines go back to normal and to let the whole muscle relax.1475

Rigor mortis applies to this.1481

Rigor mortis is when a dead body is divided aboard.1484

Why is that happen?1489

Any position that an animal is diced in, there are certain muscles that are going to be contracted position and muscles that are relaxed.1490

For instance, when my arm is down, my biceps muscle here is relaxed, but this is contracted.1500

If I die in this position, there is a lot of residual ATP that is left over the muscle that I have already generated in preparation for future events.1506

Even if the heart stops beating and the brain stops working, there is still some ATP left over.1516

After several hours, that is done and you did not make anymore because you are dead.1522

Once there is no more ATP you can no longer move.1528

If I wanted to move this on a dead body, if there is no ATP to let go of myosin off of actin, it is not going to be like their like a statue.1532

It is not going to let go without the ATP.1545

You may ask what this rigor mortis just permanently lasts, no.1547

After about 24 hours up to 72 hours later after death, you are going to get certain enzymes being released1552

that break down is just part of death that break down those proteins especially along the Z lines1561

and such that are going to just dissolve myofibrils to the point where the body is breaking down.1568

Once that happens, rigor mortis is no longer in effect.1576

More on muscles.1580

Oxygen debt, you know that if you are just sitting here like I am it is going well in terms of oxygen in using it.1584

If I go to a long distance run or sprint, your heart will start beating more and you are going to start breathing more because you try to get more oxygen to your muscles.1596

You are trying to get increase blood flow to your muscles.1606

The key to making that ATP molecule is you got to break down sugars through glycolisis.1613

This is something you learn in basic biology.1620

You break down the sugars and then the products call pirovic acid from glycolisis, you send to the mitochondria1622

which is quite abundant in the muscles because they are doing so much using of energy or ATP.1629

You use oxygen to finish what is called aerobic respiration, the process of using oxygen to get a lot of ATP out of sugar molecule.1637

If I am running really fast, even though I maybe breathing a lot more oxygen,1646

eventually what I am asking my muscles to do is exceeding the amount of ATP that is available to my muscle.1652

What is going to start happening is if I do not have enough ATP and I do not have quite enough oxygen available at that moment to make more ATP,1660

instead of pirovic acid from glycolisis going to the mitochondria, it is going to be turned into what is called lactic acid.1672

That oxygen debt as a result of me not having quite enough of the raw materials to make more ATP, I am going to make lactic acid as a part of anaerobic respiration.1680

That is that burning sensation you get your muscles.1693

Sprinting hard once around the track, most of people are going to feel that burning sensation unless you are an Olympic athlete.1696

That is lactic acid being generated.1702

Studies have shown that the lactic acid being generated can stimulate you to inhale even more oxygen1706

to try to get that lactic acid out of the muscle and get it back to pirovic acid.1714

The liver can turn lactic acid to pirovic acid and you can use that once you slow down and start making lactic acid and that burning sensation will go away.1719

Creatine phosphate this is something that is naturally available in human bodies.1733

Everybody has it and it is like an assistant to making more ATP.1740

If you do in a moments time not have enough generated ATP or you are having trouble quickly1745

attaching phosphates back into ADP, creatine phosphate has phosphates to give up.1753

It can quickly remake ATP at a moments notice as an assistant.1759

I know some people will take creatine supplements.1763

It works for some people but I would caution people relying on creatine powders to assist work outs because taking too much of it does not mean you are using all of it.1769

A lot of it could be coming out of your urine because you have creatine phosphate that is readily available1782

and a healthy person who is eating well and exercising correctly does not need that supplement.1790

Fast and slow twitch fibers.1796

Fast twitch fibers tend to be white in appearance and your classic looking muscle is a slow twitch fiber that is red.1798

I like to think about ducks versus chicken with this.1812

If you look at a chicken breast, that is white meat.1819

Ducks tend to have dark meat.1822

When you look at how a chicken moves the reason why it has a lot more white fibers here is because think about a chicken trying to fly, it is flapping its wings quickly.1826

That is thanks to fast twitch fibers.1839

You and I have a lot of fast twitch fibers in the hand region.1842

Think about how quickly we can blink our eyelids and parts of our feet.1846

You are going to have areas in the body with a lot more fast twitch fibers.1852

In some areas you are going to have more slow twitch fibers.1856

Slow twitch is not a bad thing.1859

A cow, a duck, they have greater proportions of slow twitch fibers than chickens.1861

It suits these animals and suits us for very specific purposes.1870

A slow twitch fiber you cannot move as fast but is load bearing.1874

You are able to exert yourself with those fibers and do work.1880

It might not be as fast but are able to lifting and push on things.1886

Thanks to slow twitch fibers.1891

I have heard that in parts of Europe, some families will have tests run on their certain daughter to determine1893

if genetically they have slightly more slow twitch fibers or fast twitch fibers than an average human being.1901

We are all the same species but within our species you can have slight variations in slight percentage of slow twitch fiber available in your body versus fast twitch.1908

If you do a test that is confirming that maybe it has .2% more slow twitch fibers or .2% more fast twitch fibers.1919

You might think maybe my trial is more suited towards genetically or more suited towards long distance running.1929

It is still not widely used but that is an interesting test to do.1937

When it comes to naming muscles, there is a combination of 4 characteristics that is used in naming a muscle.1942

Function, location, size, and orientation.1951

Here are some examples.1954

The pectoralis major, the major muscle of the upper chest.1956

Pectoralis is the region, this is the pectoral region or location.1960

Major here means it is big and large.1966

It is the size term.1970

Pectoralis major is a combination of the location and size naming.1972

Orbicularis oris, orbicularis comes from the fact that it orbits so that is the orientation of it.1977

It is how it sits on the part of your body.1986

Oris comes from oral.1989

This is partially function and partially location but the orbicularis oris is here on your lips.1991

It is a circular orbiting kind of muscle and it is in the oral cavity.1999

This long one flexor digitorium superficialis that helps you flex your digits.2005

It is a more superficial muscle compared to some other ones.2015

That is function kind of naming.2018

That is a location kind of naming.2022

That is also an orientation kind of naming because it is more superficial than deep.2024

This is the head, we will quickly go through this.2030

Here is the epicranius.2035

It is right in the front or top of the cranial part of the head.2037

I have heard this is called epicranius frontalis because it is right in the frontal bone.2044

The missed on the back I have heard it is called epicranius occipitalis because that is the occipital bone.2049

What is this in here?2055

Those are called aponeurosis.2058

Aponeurosis is a connective tissue that connects muscle to muscle.2060

You will also find them in between the abdominal muscles those are aponeurosis as well.2063

The termporalis muscle is here on the temple and that is an accessory muscle or synergist with this.2067

I am going to skip ahead just briefly.2077

The masseter muscle is here and this masseter muscle is the main jaw muscle to bring your mandible up.2081

The masseter is similar to mastication or chewing.2092

The masseter muscle is the prime mover or the main mover for this action.2097

If you put your finger here and clench you can feel that there is a contraction going on at your temple.2105

The term synergist or accessory muscle could be used to say the prime mover for lifting up your jaw2113

is the masseter muscle but there is a slight contraction here with the temple muscle.2121

The antagonist or opposite mover to the masseter is whatever that is lowering your jaw.2128

If the prime mover for moving your jaw up is the masseter, here is the platysma.2137

Platy means flat, this muscle has some flatness to it.2146

The platysma looks big than in this image.2152

When you open your mouth or let your jaw fall, your platysma is contracting but the masseter has to relax.2155

That is the importance of the terms prime mover antagonist.2165

It is the same with your biceps versus your triceps.2170

If I am going like this, this is the prime mover and this is the antagonist doing the opposite.2172

Orbicularis occuli, it is what allows you to blink.2178

It is similar to the naming of orbicularis oris but since it is the ocular area of the eye, it has that name.2187

Zygomaticus has it name because this is named after its location.2203

It is attached to the zygomaticus bone.2215

You can thank the zygomaticus for smiling because you can see where it is located.2218

It pulls up on the edges of your lips.2225

The orbicularis oris mentioned earlier is right here and that allows you to do this.2229

The buccinators means trumpeter.2243

The buccinators muscle is hidden here.2247

It is just deep to the superficial zygomaticus.2254

Here is that buccinators muscle.2260

It is a slightly different motion with the orbicularis oris.2262

They call it the trumpeter muscle because when you do this and you make that indentation, like you are blowing on a trumpet, that is your buccinators doing there.2266

Those are the main muscles of the head.2280

When we look at the muscle of the torso it is including parts of the tops of the arms but deltoid on this muscular main here is here and here.2283

When you look at the muscle by itself and has a triangular look like delta that is why it is called the deltoid.2300

The trapezius muscle is best viewed from the back but that is what you are seeing here.2308

People who work out their upper back a lot, you can see a bulge here and the trapezius makes up the majority of the upper back.2315

If you use your imagination, it looks like a trapezoid except it does come down to a point near the mid back.2326

That is the trapezius muscle.2334

Pectoralis major was mentioned in the previous slide that is this muscle.2336

You can barely see it in yellow but you know where it is.2343

Next up is external oblique, it is external because it is towards the outside and oblique because it is diagonal in its orientation.2346

Here are your external obliques.2357

Some people focus on those side muscles of the abdominal region when you are doing certain exercises.2361

The latissimus dorsae, latissimus means widest and dorsae those are the wing like muscles that pop at the sides of the back.2371

On a back view, they are quite large next to the trapezius and all of these here is latissimus dorsae.2385

Rectus abdominus is the last one I will tell you about here in the torso.2398

If you look at how the 6 pack is arranged, it is in these little pockets of muscle and they are connected by aponeurosis.2405

Rectus means straight parallel and abdominus is the region.2418

The reason why it is rectus abdominus is when you look closely at the muscle fibers, they are all going straight up and down.2425

It is straight/ diagonal.2435

Here you are looking at the rectus abdominus.2439

The major muscles of the arms, biceps brachial and triceps brachial.2445

The brachial has to do with the fact that we are looking at the arm here.2453

Biceps and triceps, biceps means two heads because when you look at how this muscle is attached up here there are 2 points of attachment or 2 heads.2456

Conversely when you look at the triceps brachial has 3 points of connection that is why it is triceps.2470

Brachial radialis that muscle is right here.2485

From the skeleton lessons, the ulna in the pinky side, the radius is in the thumb side.2492

Since radialis is in the name of this, here is the brachial radialis.2498

Flexor digitorium superficialis that allows you to flex your digits.2507

Me doing this, I am contracting that particular muscle.2514

The major muscles of the legs, gluteus maximus, a lot of people are familiar with it, that is the major butt muscle.2519

It is maximus because it is large.2529

There is gluteus minimus but it is slightly off to the side.2532

Rectus femoris, remember rectus means straight or parallel.2539

Femoris of course is the femur.2548

A lot of people call the front thigh muscle the quadriceps.2551

Quadriceps means foreheads but there are individual muscles there.2558

The rectus femoris is one of the major ones and it comes like that up on the top of the leg.2564

The Sartorius lies on top of that and it has to do with being a tailor.2574

The Sartorius muscle comes along here like a tailor’s thread.2582

I think that is a very interesting name that they gave it.2592

Biceps femoris, biceps means two heads.2596

That is why I am just calling this biceps in anatomy class it is not the full name because they are multi muscles that starts with the names biceps.2602

Biceps brachial, biceps femoris is actually in the hamstring area.2610

You can see here they say hamstrings that is the more common name for the back part of the thigh but the major muscle there is the biceps femoris.2615

Gastronemius is also known as the calf muscle.2630

Here is the gastronemius.2640

You can barely see it here on the side.2645

The calf muscle is attached to your heel, the Achille’s tendon or calcineal tendon.2647

It says tendon calceneus there.2656

The calceneal tendon is that heel bone is called the calceneus and that is a very strong tendon.2660

If you rupture it, it is quite painful and you are not going to be able to walk.2668

The soleus is next toward of the gastronemius.2673

The soleus is more visible when you look at the front.2676

The soleus is right here but you can see it also along the back of the leg.2684

Those are the major muscles of the body.2694

There is a lot more than what I have covered but these are major ones.2697

For some muscular disorders.2701

There a lot of disorders in the muscular system.2703

These are some of the major ones.2706

Muscular dystrophy is a genetic disorder.2708

There are a lot of types of dystrophy but what they have in common is genetically the person is unable to make distrophine.2711

A muscular protein in a proper way.2719

Distrophine makes up less than .5% of muscle tissue.2722

It is a very small percentage of what is going on.2727

There is a lot of actin and myosin, but having distrophine messed up, it throws the whole system into a whack.2730

There is no cure for muscle dystrophy.2737

It is a disease that is very unfortunate.2739

Maybe one day there will be a cure but now there are treatments for it and it is something that you do not think about until there is a problem with it.2742

Carpal tunnel might have genetic factor associated with it but in general when it comes to the carpal bones2755

and the muscles here that help you move the fingers, there are these tracks made up of muscles and tendons,2762

nerves and blood vessels that go through the carpal bones to the fingers.2771

People who do a lot of typing, who do a lot of work with their hands, maybe they do arts and stuff,2775

those people would be vulnerable because over use of your fingers for hours can lead to getting carpal tunnel.2785

Carpal tunnel is when you have swelling of the sheets of the connective tissue that is around these units2794

and that is going to be pressing up against your nerves and blood flow,2801

and that swelling in these narrow areas of the carpal bones is going to cause a lot discomforts.2807

It can start out with just tingling but over time it gets worse.2813

Surgeries can help it and there are also a lot of orgonomic devices out there that can help with carpal tunnel.2818

Hernia is when part of an organ is creeping through some connective tissues, some compartment in the body and going to areas where it does not belong.2827

There are few different types of hernia.2840

One is an inguinal hernia that is when a part of your intestine is creeping through the muscular area that separates the discrotal sac from the abdominal cavities.2842

A man who gets an inguinal hernia is very painful.2856

That is from lifting something that is too heavy and that over use of the muscles in that region can cause that organ problem.2861

Ischemia means blood starvation.2874

Anytime you have a cut off of blood to any organ that is an ischemic scenario.2878

When it comes to muscle, muscles require a lot of blood flow to function properly.2888

Bloods being cut off to a muscle, at the very least you are going to get cramping but at the worst you can have cell damage.2892

Botulism is a result of a toxin causing the muscle to not be able to function properly.2901

One of the sources is a bacteria called claustordium-.2908

This is something that is rare to get but when you do get it there is an incubation period that leads to the neuromuscular junctions not functioning properly because of that toxin.2913

Polio comes from the virus and that does eventually cause paralysis.2926

I am sure you are familiar with FDR and that particular disease because of vaccinations2931

you do not see polio in a developed world but is still does exist around the world in certain places.2937

Tetanus is from a bacterial toxin, it can also be known as a lock jaw because what happens is if tetanus gets inside your body,2945

there is an incubation period that leads to that toxin causing muscles to in a frozen contacted position.2956

That is why the lock jaw would happen.2964

There are shots that can help you not get tetanus.2966

The typical scenario is stepping on a rusty nail.2970

You can get tetanus from other sources as well.2975

The rusty nail makes sense because you have this metal object with the tetanus bacteria on it2978

that is getting deep into your tissue into where the muscle is and that can cause the tetanus.2985

Rotator cuff injury when someone who is likely to get rotator cuff injury but anytime you get a tear in the muscles that are surrounding the humerus2993

and allowing you to have that nice ball and socket motion with that joint, that can be a problem.3004

Mitochondrial diseases this is a genetic thing.3010

You have a lot of different proteins in the cellular organelle and the mitochondria that helps shuttle protons, electrons,3013

to where they are supposed to go to help you make ATP.3023

The energy molecule required for muscle to function.3026

If you have a mitochondrial disease, it could be even inherited a certain DNA combination,3029

a certain genotype that causes protein to not be in the proper structure that it should be.3039

That can make it to where maybe you are not making as much ATP as you are supposed to be making in the mitochondria.3045

That can lead to certain problems throughout life.3050

Compartment syndrome is related to ischemia because compartment syndrome is this scenario where if you have a tear in a blood vessel that is in your gastronemius.3054

Your gastronemius is surrounded with fascia and it is in its own little compartment.3068

If you have a bleed in that gastronemius unit, there could be a pressure of all that blood3073

and all that blood just emptying into that compartment can put pressure on the muscle, nerves, other blood vessels.3079

That swelling sometimes has no place to go because of that sheet known as the fascia.3087

That compartment syndrome can cause permanent damage if you go to the hospital and get it taken care of.3093

Probably the most fascinating of all muscular disorders that I have ever heard of is FOP, fibrodysplasia ossificans progresiva.3099

That is depicted in this photograph here.3108

This is a very rare disorder that has genetic factors linked with it.3111

It is when somebody gets FOP gets injured.3117

Let us say, they get a car accident and they get tears in the muscles of their chest, back, and arm.3121

Instead of their body healing that muscle to make muscle again, their body heals that tissue as bone.3129

You have a scenario here where this person, all these injuries they have in their arm and upper back has led to bone to where it does not belong.3138

That is going to lead to not living as long as the average person because these areas are going to constrict breathing in the long run.3150

There are surgeries that they have tried to fix this but if you think what is required for a surgery,3159

you have to go in surgically on a microscopic level damage certain tissues.3166

Just the surgery itself can make the problem worse.3173

There is no current cure for FOP but time will tell.3177

Those are muscular disorders.3183

Thank you for watching