Muscle length chart
Disclaimer : This information is not guaranteed to be accurate and I am not liable if you make any decisions or take any actions, in terms of medical treatment, health decisions, exercise, behavior or anything else based on the information presented. I am not telling you any decisions to make even if I use terms like "you" but am using the word "you" as part of a writing style to simplify writing. Any suggestions for what "you" should do are not for you personally to do but what someone might do as part of a exercise or nutrition program which might help some people's health and make other people's health worse. You should not do any activity that will make your health worse even if "you" should do it according to the program described. If the information is wrong and you believe it is true, act on it and it causes you problems, I am not responsible because I have warned you the information is not guaranteed to be accurate.
Purpose : This is a chart to figure out how to make a muscle in it's shortest and it's longest position. The goal is to know how to use it for end range of motion, strength training and for flexibility training. This is different than a regular muscle length chart, in that it lists categories of joint movement that are not the action the muscle performs. For example if a muscle crosses the forearm or radioulnar joint the length of the muscle might be effected by pronation or supination even if the muscle performs neither the action of pronation or supination.
Anatomy Terms
Proximal : Closer to where the point on the limb attaches to the torso in anatomical position for humans, unless the point is in the torso in which case closer to the heart.
Proximal and Distal are for comparing the location of one point relative to another point
Distal : Farther from where the point on the limb attaches to the torso in anatomical position for humans, unless the point is in the torso in which case farther away from the heart.
Proximal and Distal are for comparing the location of one point relative to another point
Origin : Usually, the proximal points where the muscle attaches. Point which usually stays stationary during muscle action
Except when the muscle origin and insertion are "reversed" by for example holding the insertion stationary either through the action of another muscle or by an external force coming from a source outside the human body.
Insertion : Usually, the distal points where the muscle attaches. Point which usually is moved by muscle action
Except when the muscle origin and insertion are "reversed" by for example holding the insertion stationary either through the action of another muscle or by an external force coming from a source outside the human body.
Muscle Length Chart Categories of Information
Shortest Muscle Length : This will essentially occur when a muscle is doing the actions listed on a regular muscle chart
Longest Muscle Length : This will essentially occur when a joint is moved in the opposite direction of the actions listed on a regular muscle chart
Does not cross this joint or any joint distal to this joint : This is important to know because moving that joint and all joints distal to that joint should not theoretically effect the muscle length for someone with no limits to their muscle strength. Except it really might effect it when strength is insufficient.
Does not cross this joint or any joint proximal to this joint : This is important to know because moving that joint and all joints proximal to that joint should not theoretically effect the muscle length for someone with no limits to their muscle strength. Except it really might effect it when strength is insufficient.
Why the position of a joint a muscle does not cross might prevent someone from achieving certain muscle lengths when strength is insufficient
I say might because I am unsure of this and it is a possibility to contemplate further.
Because muscle strength is limited moving a joint a muscle does not cross might prevent someone from producing enough force to achieve a certain joint angle on a joint the muscle does cross.
This might happen when two muscles pull on the same bone and one of the muscles crosses on a joint the other muscle does not cross. When joint A changes it's angle it may change how much force is applied by Muscle 1 on bone Y possibly changing how much force is needed by muscle 2 to maintain the same angle for joint B. If joint A changes to a angle such that muscle 2 can no longer achieve enough muscle force to maintain the angle of joint B then this will force Muscle 2 closer to resting muscle length where it can achieve more force then when it is longer or shorter than it's resting muscle length and change the position of joint B. Thus when joint A is in certain positions someone who is not strong enough might not be able to put joint B in certain positions they otherwise would be able to preventing them from achieving the desired longest or shortest length in muscle B for end range of motion strength training.
Shortens : Moving the joint in this manner should shorten the muscle
Lengthens : Moving the joint in this manner should lengthen the muscle
Could Effect Muscle Length ( CEML ) : Moving the joint in this manner should either shorten or lengthen the muscle or shorten one part of the muscle while lengthening another part of the muscle because of what joints the muscle crosses even though it is not an action nor the opposite of a action on a muscle chart.
Possible twisting or torsional shape change ( CEML )
Twisting will most likely lengthen most or all muscle fibers compared to the neutral untwisted position
In regards to forearm pronation and supination for muscles that do have listed actions of pronation or supination but cross the forearm or attach at the forearm as either a origin or insertion.
In regards to shoulder ( glenohumeral ) internal and external rotation for muscles that cross the shoulder ( glenohumeral ) but are not listed as internally or externally rotating the shoulder ( glenohumeral . )
In regards to hip internal and external rotation for muscles that cross the hip but are not listed as internally or externally rotating the hip. And so on
http://web.archive.org/web/20210228114856im_/https://www.e-education.psu.edu/matse81/sites/www.e-education.psu.edu.matse81/files/images/lesson04/torsional_stress copy.png
http://web.archive.org/web/20200812020203/e-education.psu.edu/matse81/node/2100
Possible Impure Shear Like Shape change ( CEML )
This will most likely lengthen part of the muscle and shorten the other part
One part will experience, negative strain and the other positive strain
Might not technically be pure shear strain
Maybe each part experiences shear strain but the two parts experience the shear strain in opposite directions of each other
Similar in shape change to that from a square to a "right trapezoid" or "right trapezium" in which one side becomes longer without changing angle, one side becomes shorter without changing angle, one side becomes longer while changing angle, and one side stays the same
This happens :
In regards to wrist flexion and extension for muscles that cross the wrist but do not have listed action of wrist flexion or extension. In regards to wrist radial and ulnar deviation for muscles that cross the wrist but do not have lisied action of wrist radial or ulnar deviation.
In regards to shoulder ( glenohumeral ) flexion and extension for muscles that cross the shoulder ( glenohumeral ) but are not listed as flexing or extending the shoulder ( glenohumeral . ) In regards to shoulder ( glenohumeral ) abduction and adduction for muscles that cross the shoulder ( glenohumeral ) but are not listed as abducting or adducting the shoulder ( glenohumeral . )
In regards to hip flexion and extension for muscles that cross the hip but are not listed as flexing or extending the hip. In regards to hip abduction and adduction for muscles that cross the hip but are not listed as abducting or adducting the hip. And so on
Pure Shear Strain?
http://web.archive.org/web/20210228114856im_/https://www.e-education.psu.edu/matse81/sites/www.e-education.psu.edu.matse81/files/images/lesson04/shear_stress.png
http://web.archive.org/web/20200812020203/e-education.psu.edu/matse81/node/2100
Type of Strain Muscles Would Actually Experience is not pure shear or at least not a single pure shear
https://imgflip.com/i/6qu40g
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https://www.geogebra.org/geometry
Unknown : It is unknown or controversial if a muscle does this joint action. For a hypothetical example if a muscle has a origin proximal to the elbow and an attachment distal to the elbow it should logically either flex or extend the elbow but if a chart does not list elbow flexion or extension even though I think it should logically do one or the other I will put down "unknown" for both flexion and extension because it logically should do exactly one of those actions, and no more nor less than one but I do not know which one based on the chart and furthermore the chartmakers do not claim it does either one. I will also put unknown for controversial things where people disagree on a muscle action based on charts or what I read.
Yes but direction unclear : This is for transeverse plane rotation of the foot, ankle or leg at knee height and below. This is for actions that rotate the tibia and or fibula relative the the femur in the transverse plane or that rotate the foot in the transverse plane relative to the tibia and or fibula. Many foot doctors have chosen to use a different definition of pronation and supination for the foot, ankle or leg then is used for the hand, wrist or forearm leading to ambiguity therefore I will assume the anatomical charts can not give a non ambigous proper explanation as to the direction of this rotation until this problem is fixed without a lengthy explanation which is rarely or never present. This might also be used for wrist ulnar or radial deviation if a chart says, wrist adduction or wrist abduction which are vague terms instead of wrist ulnar or radial deviation or any other term where either the action or the opposite of a action is listed but the direction is unclear.
Copyright Carl Janssen 2022
Resources
Draft Version
https://postscarcityfitness.blogspot.com/2022/07/active-and-passive-insuffiency-muscle.html
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