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asolimene53
05-08-2008, 11:13 PM
Thanks for your prompt reply.

I have read and re-read your comments especially in response to my
fourth point. Most likely due to my own limitations - I did not
fully understand it. I don't believe it is what I said or meant. I
would appreciate if you could expand your comments.

Dr. A. Solimene

Quoting Greiner Thomas :

> A few comments in response to my response on the tibialis anterior. I
> think we are mostly in agreement, but perhaps talking past each other.
>
>
> "1. The anatomical planes of reference are arbitrary.
>
> 2. The line of force or action of any muscle does / do not occur "along
> an artificial, and arbitrary, geometry" - it occurs where it occurs AND
> during the range of motion of the involved body segments the position of
> the line of action of a muscle continuously changes."
>
> This was my point exactly, although perhaps you say it better. The
> anatomical planes are artificial and arbitrary and if you limit your
> investigation to those planes you should not be surprised that muscle's
> action line has an oblique orientation.
>
> "4. I respectful disagree that the line of action need be in the
> sagittal plane to obtain meaningful data. It is done mathematically."
>
> I agree completely. This is a consequence that a muscle's force of
> action "occurs where it occurs." That, is another way of saying that you
> should not expect of find anatomical evidence of a muscular action line
> if you limit your investigation to a single anatomical plane.
> Investigations in three dimensions may eventually allow you to resolve
> an action line to a particular plane, but before you can do that math
> you need to know what the muscle does when it does something. Inasmuch
> as Tibialis Anterior is a dorisflexor and an inverter (or perhaps
> sometimes and everter) the line of action of its insertion tendon will
> lie oblique to the sagittal plane. Therefore you cannot caputre the
> muscle's action line if investigation is limited to that plane. This is,
> effectively, the same thing as saying that for the "TA there are more
> than one line of action."
>
> Thomas M. Greiner, Ph.D.
> Anatomist and Physical Anthropologist
> Dept. of Health Professions
> University of Wisconsin - La Crosse
> 1725 State Street
> La Crosse, WI 54601 USA
>
> -----Original Message-----
> From: as572@columbia.edu [mailto:as572@columbia.edu]
> Sent: Thursday, May 08, 2008 12:16 PM
> To: BIOMCH-L@NIC.SURFNET.NL
> Cc: Greiner Thomas
> Subject: Re: [BIOMCH-L] Locating Tibialis Anterior tendon's action
> lineusing MRI
>
>
> Dr Greiner,
>
> Four thoughts and observations ..
>
> 1. The anatomical planes of reference are arbitrary.
>
> 2. The line of force or action of any muscle does / do not occur "along
> an artificial, and arbitrary, geometry" - it occurs where it occurs AND
> during the range of motion of the involved body segments the position of
> the line of action of a muscle continuously changes.
>
> A long while ago - some anatomists differentiated "Pure" from "Compound"
> motion.
> Pure motion was supposed to occur within (parallel to) the three
> anatomical planes. Compound motion was any movement that
> simultaneous intersected two or more of the anatomical planes.
> Fortunately this unwieldy descriptive method is no longer widely used.
>
> a. To my knowledge there is no general agreement as to action of the
> tibialis anterior muscle. In Lanz and Wachsmuth's anatomical atlas, the
> tendon to the tibialis anterior lies on the axis of inversion and
> eversion, if that is its true location, i.e. its moment arm relative
> to this axis is zero. One can therefore conclude that in the
> anatomical position the TA is neither, and functions as a dorsi-flexor.
> This conclusion is perhaps most reasonable.
>
> I don't recall the reference, but I remember learning that electrical
> stimulation of the belly of the TA would produce inversion in @50% of
> cases and in @50% eversion. It may be worth redoing this study.
>
> 3b. In the case of the TA it is realistic to consider the reversal of
> muscle action during the range of motion of the foot at the ankle.
> This could be associated with the recruitment of muscle force during
> movement / locomotion.
>
> 4. I respectful disagree that the line of action need be in the sagittal
> plane to obtain meaningful data. It is done mathematically.
>
> For Dr. Miller -
> Most likely, given the width of the tendon and the area of attachment of
> the TA there are more than one line of action.
>
> For Thomas -
> FYI - I am also an anatomist and physical anthropologist
>
> Cheers
>
> Dr. Alfonso Solimene
>
>
>
> Quoting Greiner Thomas :
>
>>
>> I believe the problem you are encountering is due to the fact that
>> that action of tibialis anterior is oblique to the anatomical
>> reference planes. You are forcing the measurement of muscle activity
>> to occur along an artificial, and arbitrary, geometry.. Inasmuch as
>> tibialis anterior is primarily a foot inverter, I doubt that you would
>
>> ever be able to obtain realistic and meaningful measured values if
>> your perspective is limited to the sagittal plane.
>>
>> Thomas M. Greiner, Ph.D.
>> Anatomist and Physical Anthropologist
>> Dept. of Health Professions
>> University of Wisconsin - La Crosse
>> 1725 State Street
>> La Crosse, WI 54601 USA
>>
>> -----Original Message-----
>> From: * Biomechanics and Movement Science listserver
>> [mailto:BIOMCH-L@NIC.SURFNET.NL] On Behalf Of Stuart Miller
>> Sent: Wednesday, May 07, 2008 9:10 AM
>> To: BIOMCH-L@NIC.SURFNET.NL
>> Subject: [BIOMCH-L] Locating Tibialis Anterior tendon's action line
>> using MRI
>>
>> Hello all,
>>
>>
>>
>> My colleagues and I have recently started to calculate the moment arm
>> of the tibialis anterior and Achilles tendon. The method we are using
>> is the Reuleaux graphical analysis. The images of the ankle are
>> collected using MRI techniques. The images are collected in the
> sagittal plane.
>> This technique has been described in Maganaris et al. (1999); Clinical
>
>> Biomechanics 14 pp661-666.
>>
>>
>>
>> The problem we are experiencing is of locating the action line of the
>> tibialis anterior. The tibialis anterior tendon crosses the sagittal
>> plane, so only an oval cross-section can be seen. This does not appear
>
>> enough to accurately locate the action line of the tendon.
>>
>>
>>
>> I am wondering if anyone has experienced this problem whilst using
>> this technique, and if so, can suggest any solutions.
>>
>>
>>
>> The action line of the Achilles tendon is easy to see as it acts along
>
>> the sagittal plane.
>>
>>
>>
>> I will forward a summary of the responses in a few weeks.
>>
>>
>>
>> Thank you in advance.
>>
>>
>>
>>
>>
>> Stuart C. Miller BSc. (Hons)
>>
>> Centre for Sports Medicine and Human Performance
>>
>> Brunel University
>>
>> London
>>
>> Middlesex
>>
>> UB8 3PH
>>
>>
>>
>>
>>
>>
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>
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