Questions tagged [muscles]

The contractile tissue of animals derived from the mesodermal layer of embryonic germ cells.

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Why is there a mass limit on biological powered flight?

So, this is one thing I never fully understood. There are a lot of reasons for a flying creature to be limited in mass, from energy consumption to material strength. However there seems to be a reason ...
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Is there a minimum amount a muscle can move? And thus, gaps in our movement?

Lately I've been thinking about something, based on my knowledge my chain of reasoning works like this... When you want to move a muscle your brain sends an electrical nervous impulse along the chain ...
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Why does flicking a finger generate so much more force than extending it quickly?

Flicking a finger (holding it back with e.g. the thumb while building up "pressure" against the thumb, then releasing) is much more powerful than just uncurling the finger quickly. I tried to do the ...
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Partial muscle fibre contraction

I'm being taught that: a muscle fibre spans the entire length of the muscle, from the originating tendon to the inserting tendon. The question is, can a muscle fibre contract only partially? Say, if ...
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Are your finger muscles and tendons interconnected?

Are finger muscles and tendons interconnected? If they are interconnected, then if i exercise one finger will it train the other fingers since they are interconnected and share the same muscles in the ...
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Biochemistry of pleasure of/desire for physical exercise in mammalians and humans?

Are there some known biochemical mechanisms, that induces desire for/pleasure of physical exercise in mammalians and humans? I have heard, that horses can not live without physical exercise and they ...
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ATP and Muscle Contraction

I have a question regarding how molecular interactions manifest in physical actions - such as hanging from a bar. To the best of my understanding, when it comes to the contraction of muscles, ATP is ...
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What trajectory do action potentials take, from initial visual stimulus all the way to motor function?

Say we see a mosquito, and our brain tells us 'hey that's a mosquito, you should kill it.' Then we move our hands and slap/clap it. The initial visual stimulus is translated to an action potential ...
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Does loss of dopaminergic neurons totally eliminate voluntary muscular control?

Breathing is a function that is not only autonomic, but can also be temporarily overridden and placed under voluntary control. In fact, you are now breathing manually. Now, suppose that someone has ...
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For each movement performed by both the gluteus minimus and medius, what percentage of the movement do the gluteus minimus and medius account for?

From what I read on Wikipedia, all functions of the gluteus minimus are mirrored by the gluteus medius. Additionally, the gluteus medius is larger than the gluteus minimus (see comparative images here)...
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What muscle models describe “strengthening”?

As I understand it, muscles grow in strength when they are subjected to loads larger than they are used to handling. This causes local damage to the muscles cells and, through an immune system ...
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How does isometric contraction work?

What exactly happens to myosin during isometric contraction? I suspect that either myosin heads just "freeze" in the middle of crossbridge cycle, or go through full crossbridge cycles repeatedly at ...
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How does shoulder rotation work when the arm is overhead?

Anatomy references state that the humerus is externally rotated by infraspinatus, and teres minor, and internally rotated by subscapularis. All the illustrations I can find of these muscles have the ...
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Can one assess muscle strength through imaging (e.g., MRI)? If so, though which type of imaging and how accurate is it?

Can one assess muscle strength through imaging (e.g., MRI)? If so, though which type of imaging and how accurate is it? On How does muscle size relate to strength?, I read this answer from Moses (...
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Is “muscular attachment” synonymous to tendon? (when talking about the insertion of glutei medius and minimus to greater trochanter of the femur)

I have read the following two terms in an MRI report (both points refer to the insertion of gluteus medius/minimus to greater trochanter of the femur): mild degeneration of the muscular attachment ...
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What is a myotube?

If I understand correctly, the following images show the main components in a human skeletal muscle: From Life: The Science of Biology: From Human Physiology/The Muscular System in wikibooks: ...
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Where does the gluteus medius attach to the greater trochanter compared to the gluteus minimus attachment?

Where does the gluteus medius attach to the greater trochanter of the femur compared to the gluteus minimus attachment? Is it above, below, next to it, etc.? Ideally I'd like to know the distance as ...
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Can disorders involving involuntary muscle twitches and spasms have a hypertrophic and increased residual muscle tension effect?

Meaning disorders specifically like myokymia, myoclonus (positive and negative) and fasciculations. From the section of the literature I've seen, sometimes passing mentions are made when the disorder ...
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Does constant pressure cause muscle atrophy, and if so, why?

I read on https://en.wikipedia.org/w/index.php?title=Gluteal_muscles&oldid=876760828#Clinical_significance: Sitting for long periods can lead to the gluteal muscles atrophying through constant ...
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Mechanism of redirected blood

I've read several fitness articles mentioning redirected blood flow to muscles that are in use. However, they never mention how it works. Is it local and specific to the muscles in use? Or, for ...
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What is the tensile strength of muscle?

So I am looking at determining the pressure needed to impale a person with an object of a given size and shape. To figure this out, I believe I need to know the tensile strength of skin, bone, and ...
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Difference in timescale of tissue movement vs cellular differentiation

I would like to better understand the difference in the timescales that cells seem to function. For example, how is it that muscle cells can move within seconds or less under stimuli such as hormones ...
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Can the heart and other muscles function without creatine/phosphocreatine?

Skeletal muscles in the body have a small reserve of ATP. During the first few seconds after contraction, phosphocreatine is used by the enzyme creatine kinase in order to phosphorylate ADP to ATP ...
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Are there specific theories as to what causes cold[-water] muscle cramps?

The field of what might cause cramps is quite contested with a lot of controversy around the heat/dehydration cramps, but I find it surprising that no specific theories appear to have been proposed (...
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Why is the ingestion of salt and water beneficial to muscle cramp

According to Wikipedia, muscle cramps are caused by the inability of myosin fibers to break free from the actin filaments during contraction, resulting in a prolonged contraction. A lack of ATP would ...
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Can muscles work as brakes?

When I walk downhill I lose potential energy. If I descend 100m in, say, 10 minutes I lose potential energy at a rate of about 114J/s (114W). Where does the energy go? Not into kinetic energy ...
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How much energy can one muscle contraction deliver?

How much energy is available in a single muscle contraction? I'm guessing the correct units are J/kg, but I'm open to more correct units. I'm looking for work done, not total energy dissipated (not ...
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How fast can muscle fibers relax

I can find a great deal of information about how muscles contract, and how we divide them up into fast twitch and slow twitch and so forth. However, I can't seem to find anything on how fast a muscle ...
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Are there known counterexamples to Hennman's size principle for muscle unit recruitment?

It is known that generally muscle units are recruited from small to large, and that typically also means slow to fast twitch. This principle is called Hennman's size principle. I've seen many ...
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How is breathing involuntary if the muscles that control it are skeletal?

How is breathing involuntary if the muscles that control it are skeletal? Breathing is involuntary. However, the muscles that control it are skeletal: intercostal muscles and the diaphragm. Are there ...
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Contracting mouth muscles as reaction to taking in specific food items

When eating very specific food items, especially confectionery like (salty) liquorice, (it feels as if) the muscles of my mouth contract, right when it hits my tongue. Does anyone know why this ...
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Apart from nerve cells and muscle cells, what types of cells do not undergo mitosis in adult man?

Neurons and muscle cells in adult humans do not have the ability to divide by mitosis, so they can not repair themselves and their cell cycle remains in the interphase. I’m looking for more cells with ...
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Etymology of eccentric/concentric contractions

I was wondering if anyone knew why the terms eccentric and concentric were chosen to refer to lengthening and shortening muscle contractions? The basic etymology of the words are to do with ...
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What is official term for contraction induced muscle “vibration”?

I can activate my tensor tympani muscles at will, it makes me hear rumbling bass sound becose the muscles "shiver / "vibrate" when contracted. Also when I put cleched fist to my ear I can hear it too. ...
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Why proximal muscle weakness is seen earlier than distal muscle weakness in Dermatomyositis?

It is said that in dermatomyositis(DM) , proximal muscle weakness is seen earlier than distal muscle weakness. It is also said that , DM is due to damage to small blood vessels contributing to muscle ...
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When muscles contract is the process similar to how non-newtonian fluids react?

I'm trying to understand how muscles contraction/tension works but getting loss in on the cellular level. From my understanding, when muscle tissue need to contract, the cells are flooded with calcium?...
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How efficiently does the human body convert the energy stored in fat into kinetic energy?

I read that one gram fat contains 9 kcal energy. There are many tables around claiming that x type of exercise for t duration ...
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How many muscles work for a smile and how many when you are sad? [closed]

Muscles works in both cases but it’s seems difficult to understand that how they work
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does being battered build muscle?

My crude understanding of how people normally go about building muscle is something like this following 2 step process: 1) a person can lift weights (for example), which tears muscle and stimulates ...
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Myoglobin in meat

When looking at the reason why some meat is white and the rest is red, I found out it is down to the levels of myoglobin as higher levels of myoglobin are found in "slow twitch" muscles. I have also ...
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why do we tighten out muscles against cold?

When I'm in shower and I want to open the cold water on myself suddenly I make my muscles so tight before I open the water and that helps so much in being able to handle the shock. Why does tightening ...
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Skeletal muscle has got many many peripheral nuclei. What does “peripheral” mean here?

Cardiac muscle has got a central nucleus similar to smooth muscle, but skeletal muscle you may recall has got many many peripheral nuclei. What does "peripheral" mean here?
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Difference between reciprocal inhibition and regular muscle movement?

I was looking into a condition I have, anterior pelvic tilt, quite a bit. I ran into a website describing part of the issue as reciprocal inhibition. This was my confusion: Reciprocal inhibition, ...
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Does estrogen increase muscular growth in females?

Regarding humans it is said that most psychological effects caused in men by testosterone are caused in women by estrogens. There are many studies on that, particularly regarding temporary shifts of ...
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Is the ACh receptor more permeable to sodium ions?

The AChR is permeable to sodium and potassium ions only and has a reversal potential of 0mV. However the Nernst potentials for sodium and potassium ions is ~ +60mV and -88mV respectively. Taking a ...
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Pictures of trigger point muscle fascia

Are there any pictures of an actual trigger point looks like? All I am able to find online are animations.
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If hands are folded with both index fingers parallel, they will come closer and touch eventually?

I have a question out of curiosity. It is just something I found out/discovered: if I fold my hands into each and let my two index fingers (see picture) be in parallel then they will eventually come ...
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Exhaustion of skeletal muscle and ligaments

I read somewhere that while doing lifting back should be straight(means normal curve), so that erectors muscle in back do the work but it gets tired easily. Hence we form curve on our back like when ...
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seafood muscles - how do they work?

Today, first time in my life I ate seafood. It was a squid and a calamar. Note that I am biology layman, so please be merciful :( While dissecting my food I noticed that the tissues of those ...
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advantages of shivering in cold environments

When we feel cold, our the muscle tries to generate heat by shivering and the brown adipose tissue tries to generate heat by non-shivering methods. The muscle generates heat but also spends energy on ...