What is Muscle: Definition and 97 Discussions

Muscle is a soft tissue found in most animals, and is one of the four basic animal tissues, along with nervous tissue, epithelium, and connective tissue. Muscle cells contain protein filaments called myofilaments of actin and myosin that slide past one another, producing a contraction that changes both the length and the shape of the cell. Muscles function to produce force and motion. They are primarily responsible for maintaining and changing posture, locomotion, as well as movement of internal organs, such as the contraction of the heart and the movement of food through the digestive system via peristalsis.
Muscle tissue is derived from the embryonic mesodermal germ layer in a process known as myogenesis. There are three types of muscle, of which skeletal and cardiac muscle are striated and smooth muscle is not. Muscle action can be classified as being either voluntary or involuntary. Cardiac and smooth muscles contract without conscious thought and are termed involuntary, whereas the skeletal muscles contract upon command. Skeletal muscles in turn can be divided into fast and slow twitch fibers.
Muscles are predominantly powered by the oxidation of fats and carbohydrates, but anaerobic chemical reactions are also used, particularly by fast twitch fibers. These chemical reactions produce adenosine triphosphate (ATP) molecules that are used to power the movement of the myosin heads.The term muscle is derived from the Latin musculus meaning "little mouse" perhaps because of the shape of certain skeletal muscles or because contracting muscles look like mice moving under the skin.

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  1. dcmf

    Torque question in Deltoid muscle

    Here's a picture the question provided. I tried solving this question two ways (assuming the axis of rotation is at the shoulder joint) and am getting wildly different answers. Some potential reasons there's a discrepancy: - I'm not super confident about my use of the torque equation...
  2. EXO-0826

    Electric muscle for a robot

    Project for creating electro-muscle fiber for robotic drives The drive consists of a central spiral guide and external thin conductors as (muscles) as well as coils at the ends of the muscle, and is in a strong elastic casing. Do you think how effective such a muscle will be and from which...
  3. D

    What is the cost of muscle flexibility?

    Hi everyone How is it advantageous for muscles to lose flexibility when certain movements are not practised? For example, if you lose muscle mass after stopping weight training, you will need less calories to feed the remaining muscle. What benefit (if any) does the body get from losing...
  4. M

    How human strength can increase without increased muscle size?

    I know this is a hypothetical question, but we can still have a general idea for how we could do it in the future. I wonder how theoretically with good enough technology a human can achieve a super-human strength(or close to it) without large muscles or non-biological components attached to...
  5. kolleamm

    Muscle contraction question about myosin

    I've been doing research on how muscles work using the page below and overall I get the general idea, however I still have some questions. Why does ADP and Pi detach from the myosin head during the power stroke and why does the attachment of ATP to the myosin head cause the myosin head to detach...
  6. kolleamm

    Most effective way to cause hyperthrophy in a muscle?

    There's many articles online about the best types of exercises etc... but I want to look at it from a scientific/molecular point of view. What sort of movements would increase the chances of a muscle tearing (microscopically)? Is there a threshold for the amount of weight you have to lift in...
  7. C

    Climbing with Tension: Exploring Muscle vs. Mechanical Energy

    Here the upward force on the camp is Tsinx <=360 Therefore T(max)=720N Here they have taken the equation that T-mg=ma This shows that the man is climbing due to tension. But I can't visualise how tension helps in climbing. Isn't it our own energy that helps us to climb. The muscle energy gets...
  8. Newby

    Calculate the quadriceps muscle force

    Hi guys, I'm new here. So I have this biomechanics module which is completely out of my league (it's compulsory but it's not what I want to do). Could someone help with the following? It's about static and dynamic loads calculation. Calculate the quadriceps muscle force applied through the...
  9. K

    Still's disease and muscle movement

    What muscle or tendon is involved when you tried to touch the armpit of the other side of the body and there is slight muscle or tendon pain for the arms that reached out to the other armpit ? I feel some mild muscle pain last night after gym and just want to see the anatomy involved. I'm not...
  10. nscozzaro

    Creating a (synthetic) song from a zebra finch's muscle

    Just testing out what happens when I click on this. Where is the discussion thread created?? EDIT Now I can't figure out how to delete this
  11. Miopen

    I How Can Muscle Strain Be Measured?

    I am trying to figure out if there is a way to measure muscle strain. If I apply a force F to compress a hand grip to the maximum distance x The work done to compress the hand grip is F*x Work done = Fx Since work done = energy used, I can change the equation to: Energy used = Fx When...
  12. Asmaa Mohammad

    Physiology of the muscles: The T Tubules

    Hi all, My textbook says that the T tubules, which form an extensive network of transverse tubules that surround myofibrils, can carry the wave of action potential from the surface of the muscle fiber to the cell interior. Could you help me understand the sentence in bold because I'm not sure...
  13. James_The_Ern

    Calculating torque of rotator cuff muscle

    Homework Statement [/B] Rotator cuff strength test. Patient's elbow is flexed 90 deg. while the shoulder is abducted 90 deg. and externally rotated 90 deg. The therapist applies pressure to the dorsal surface of the hand/wrist. If this is the patient's dominant arm, and the length of her upper...
  14. annanause

    Muscle tension required to lift a child at a constant speed

    Homework Statement When a mother lifts he child with her foot (as shown in figure) what force should the upper muscle exert to lift her child at a constant speed? Homework Equations W = F x D f = mg I think these might be the right equations to use, correct me if I'm wrong. The Attempt...
  15. kostoglotov

    Energy dissipated by a loop of muscle in an MRI machine

    edit: turned out to be a calculator typo...mods feel free to delete this thread if you wish, I won't complain. Homework Statement [/B] Having issues with part a) imgur link: http://i.imgur.com/4hzLyhb.jpg Homework Equations Resistivity of muscle (from table in text): \rho \approx 13...
  16. Marie Cailey

    Could I use this as a factor that affects muscle fatigue

    Could I use "The intensity of muscle contractions" as a factory that may affect how quickly muscles become fatigued? I'm doing an experiment, but is this a legitimate idea? Would my hypothesis be "The intensity of muscle contractions in the body affects how quickly muscles become fatigued"?
  17. N

    Work applied to a spring by my finger muscles

    I take a spring and expend work to compress it with my fingers thereby increasing the potential energy of the spring. After it is at its final compressed state, am I doing work?
  18. caters

    Muscle Fiber Theory: Speed & Endurance Explained

    There is a theory that the type of muscle fiber an animal has most determines its speed and endurance. According to this theory the cheetah which gets exhausted after 45 seconds of chasing has mostly fast twitch muscle fibers. Also according to this theory we humans have mostly slow twitch...
  19. W

    How can I use Pneumatic Muscles as Hydraulic Muscles?

    Hi everyone, this is my first post I was wondering how can I turn a pneumatic artificial muscle into a hydraulic one using water. http://www.instructables.com/id/How-to-make-air-muscles!/ These are the air muscles I was planning on using. What sort of pump would I need? Please be specific as...
  20. X

    FDTD of (ultrasound) wave propagation through muscle

    Im a mechanical engineering student currently, with a third year project of simulating ultrasound propagation through the abdomen. Currently i just want to simulate it going through muscle with no obstacles. I don't really understand where to start, I have formed some equations based on the wave...
  21. C

    Does CNS in spine have single fiber per inervated muscle?

    if I can move specific muscle in my toe via brain command, does this mean that in spinal cord there is a specific fiber that extends from brain to that toe? And let's say if in a lab rat we cut that single CNS fiber, the muscle affected will stop working without any other consequences to the...
  22. M

    Maintaining Muscle Tone: Why it Matters for Everyone

    This is NOT my home work...just curious. Why would a person, even one that isn't interested in "buffing" up want to maintain good muscle tone?
  23. Q_Goest

    Are there 2 different biological processes to provide muscle energy?

    I don’t jog much. In the past I’ve only gone up to about 2 miles. At that point it seems like I can’t go much further. I hit this ‘brick wall’ and I don’t have any energy left. I’ve never tried jogging much past about 2 miles. Last week, I went jogging for just over 8 miles though. It was...
  24. J

    Sympathetic nervous system activates major skeletal muscle?

    Is is true that "Sympathetic nervous system activates your heart and major skeletal muscles? Thank you for your help!
  25. omega5

    Calculating force required of the deltoid muscle - statics problem

    Homework Statement Hello and thank you in advance for your help! I am taking an introductory algebra-based physics class and am trying to solve this problem: Suppose an arm holds an 5.8-kg mass. The total mass of the arm is 3.3 kg. Gravity acts from the center of the arm, which is 24 cm away...
  26. S

    Confusion about length-tension relationship of muscle

    I am trying to conceptually understand this relationship. One thing that's not helping is I keep hearing the phrase "the resting length" of muscle. It's using the word "THE" as if there is one resting length. This phrase implies that the length stays the same no matter how bent my elbow is at...
  27. H

    Muscle contraction-invoke from outside the body

    Hello, Am not studying biology am engineer but iam just wondering if it is possible to make a muscle contract through external voltage maybe through some electrodes connected to some area on the skin. Regards Hisham
  28. N

    Greatest Lever Arm: Calculating Force at Elbow Joint

    Homework Statement The diagram is attached. It is asking which position has the greatest lever arm.Homework Equations The Attempt at a Solution So, I know that the elbow is the fulcrum but what I'm struggling with is how to draw the force arrow. Where is the force coming from and where is it...
  29. V

    Muscle Activation Techniques ?

    "Muscle Activation Techniques"? I'm working on getting more physically active and fit, and I've received a recommendation for a (patented, naturally) exercise program (or perhaps "paradigm" is a better word) called "Muscle Activation Techniques" (main site). I know there's a lot of BS in the...
  30. P

    Medical If I'm losing muscle mass , are some of my muscle cells actually disappearing?

    If I'm "losing muscle mass", are some of my muscle cells actually disappearing? I've been running a lot lately and losing weight. Mostly getting leaner, but recently I've started to worry about losing muscle mass. I used to lift weights a lot, but I haven't done that in a few months. If I keep...
  31. M

    Why is glucose stored as glycogen in the liver and muscle?

    Homework Statement Why does the human body spend two high energy phosphate bonds to store glucose as glycogen in muscle and liver, and not just as glucose? What is the advantage in using energy to polymerize the glucose molecule? Homework Equations The Attempt at a Solution...
  32. L

    Cutting through hardened steel with muscle power

    Would it be possible for a reasonably built human to abrade through hardened steel if he had a blade made out of diamond? Or is human muscle power insufficient to break the chemical bonds?
  33. F

    Medical Need help with ways to measure muscle activity

    I'm doing a university project in Sweden where i want to continuously measure the activity in the Bulbospongiosus muscle. Is there any cheap easy method/instrument for doing this or do i need expensive professional medical equipment for this? The main problem i see is how to isolate the...
  34. S

    Ultrasound intensity in fat, muscle and bone

    Homework Statement The specific impedance of fat, muscle and bone are 1.4 x 106 kg m-2 s-1 , 1.6 x 106 kg m-2 s-1 and 6.5 x 106 kg m-2 s-1 respectively. The linear absorption coefficients in fat and in muscle are 0.24 cm-1 and 0.23 cm-1 respectively. A parallel beam of ultrasound of...
  35. narrator

    Muscle memory or normal memory?

    A lot of things we do, are done seemingly without thinking. Where is the line between muscle memory and normal memory/learning? And are there other things at play? A few examples: One of the doors in my house is a sliding door. I don't usually close it all the way with my hand, instead...
  36. V

    Gastrocnemius muscle tension

    Homework Statement The gastrocnemius muscle, in the back of the leg, has two portions, known as the medial and lateral heads. Assume that they attach to the Achilles tendon as shown in the figure. The cross-sectional area of each of these two muscles is typically 30 cm^2 for many adults...
  37. GRB 080319B

    Medical Permanent muscle loss in zero-g

    Why is there permanent muscle loss from space travel? Is this general muscle atrophy or specific to certain muscles (i.e., which muscles don't experience permanent atrophy and why)?
  38. E

    Calculating the Force of the Deltoid Muscle to Raise an Arm

    Homework Statement The main muscle responsible for raising an arm is the deltoid. The deltoid muscle connects at the upper end of the shoulder, extends over the upper arm bone (humerus), and attaches near the elbow. Effectively there are three forces involved in raising the arm: (i) the force...
  39. J

    A-Band & I-Band in Sarcomeres: Causes of Dark & Light

    What causes the A-band to be dark in a sarcomere? Conversly, what causes the I-Band to be light?
  40. S

    Action potential of a skeletal muscle fibre,where is calcium?

    Now I follow this pic, there is no mention of opening of calcium channels anywhere. So how do skeletal muscles contract, without calcium. Incontrast action potential of a cardiac muscle has plateu phase and calcium channel involvement. Thanks :smile:
  41. A

    Tension in a rope with weight held by a muscle builder

    Homework Statement A muscle builder holds the end of a massless rope. At the end of the rope, a 15 kg ball is hung as shown in the figure. What is the tension in the rope if the angle \theta in the drawing is 4.5^{}o? Homework Equations g = 9.8m/s^{}2 F = mg Trigonometrical functions The...
  42. Z

    Medical Muscle groups to improve posture

    Hello, I want to improve my posture. I tend to slouch and walk with my head jutted forward. I hear that muscle strength affects posture. Is this true? If so, which group of muscles should I strengthen to improve my posture? If possible, can you also supply some reliable links for correct...
  43. M

    Human frequency and muscle contractions

    Is possible for human muscles to contract from resonance at certain levels/ranges of frequency? I have been a lot about how with the right frequency, one can induce contractions in diff parts of the human body. Does anyone know about this? If this is true, then what is the way you can...
  44. M

    Muscle relaxant/stimulant circuit

    Hello, For my final project in a college introductory circuits class, I am supposed to build something that produces a "wow" factor. I am interested in building a muscle stimulant, and already found some circuit schematics online that I could use. I am now wondering if anyone has any creative...
  45. lisab

    Medical Cure for muscle tics - how does it work?

    "Cure" for muscle tics - how does it work? Many years ago, someone told me of a cure for muscle cramps that I assumed was an old wive's tale: you press or pinch your upper lip, between your mouth and nose, and maybe use a gentle rubbing. I rarely get muscle cramps but I do occasionally get...
  46. F

    Torque by a Muscle: Calculating Fb & Force Applied at Elbow

    Homework Statement A man holds a 196 N ball in his hand with the forearm horizontal as shown on the drawing to the left. He can support the ball in this position because of force, Fb from his bicep flexor muscule which is applied perpendicular to the forearm. This force applies a torque...
  47. S

    Action potential and strength of muscle contraction?

    Hello guys, Although the response of a motor unit is all-or-none, the strength of the response of the entire muscle is determined by the number of motor units activated. Nerve impulses passing down a single motor neuron will thus trigger contraction in all the muscle fibers at which the...
  48. S

    Why don't muscle cells burst when you exercise?

    One way muscle grows is muscle hypertrophy where sarcoplasmic fluid increases inside the muscle cell. Wouldn't this burst the cell membrane, I can understand how organelles can replicate but what about the cell membrane. I know this sounds like a stupid question but please help. Thanks :smile:
  49. S

    Understanding Muscle Tetany: Causes, Symptoms, and Treatment Explained

    Hello guys, So is tetany repeated involuntary contractions or just one smooth contraction? If the rate of action potential is rapid wouldn't that give repeated contractions? Also cardiac muscle doesn't have tetany for some reason? Thanks for anyone who can improve my understanding of tetany...
  50. T

    Extra Muscle Power: Devices for Arms, Legs & Beyond!

    Umm, is there a device that you can put on your arm or leg or somewhere that gives you extra muscle power (maybe artificial muscles). Not that I need it (ladies :cool:), I'm just interested. And let me crush hope of the smartass that's going to say steroids.