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Ankle Extension - Flexion

Discussion in 'Biomechanics, Sports and Foot orthoses' started by markjohconley, May 30, 2016.

  1. markjohconley

    markjohconley Well-Known Member


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    Whooa, again, now, admittedly on wikipedia, this,

    'These terms refer to flexion between the foot and the body's dorsal surface, considered the front of the leg, and flexion between the foot and the body's plantar surface, considered the back of the leg. ...
    These terms (referring to plantarflexion and dorsiflexion) are used to resolve confusion, as technically extension of the joint refers to dorsiflexion, which could be considered counter-intuitive as the motion reduces the angle between the foot and the leg.'

    How does one 'consider' 'the body's dorsal surface' 'the front of the leg'? and vice versa ...... and then 'technically extension of the joint refers to dorsiflexion'; now i thought i had the ankle sagittal plane motion covered, with ankle flexion being dorsiflexion?

    Are podiatrists the only health profession that exclusively use the terms, dorsiflexion and plantarflexion, to describe ankle sagittal plane motion?
     
  2. every allied Healthcare person I have ever spoken in many different countries uses Plantar / Dosiflexion to describe extension/flexion of the Ankle and joints distal to the ankle
     
  3. markjohconley

    markjohconley Well-Known Member

    Thanks Mike, methinks i may have been a tad pedantic; it's easily understood why 'we' do, end of thread; all the best, mark
     
  4. Rob Kidd

    Rob Kidd Well-Known Member

    As always, back to basics. I had a private conversation with Mark last night and he persuaded me to write something to the arena.

    anatomy is a four dimensional subject - in order to understand (as against merely "learn"), one has to delve into time - either embryological time (ie ontogeny) or evolutionary time (ie phylogeny) - which one depends upon the questions you are asking. Frequently they tell you the same thing - and the foot is really good at this. Flexion brings flexure creases together - extensions takes them apart. So that begs the question: why does the shoulder and hip flex forward (somewhat modified in the should as a result of the bipedal habit), while the elbow flexes forwards yet the knee backwards? Why does the wrist flex forwards but the ankle backwards (plantarflexion = flexion)? Why is the pollux positioned laterally but the hallux medially? Why is the nerve supply from the brachial plexus essentially linear, while the lumbo-sacral plexus twisted (ie posterior portion supplies anteriorly and visa versa)?

    This is not rocket science - the answer lies in both ontogeny and phylogeny. If one examines basic human embryology, one will find a foetus at about six weeks with both plantar and palmar surfaces pointing forwards (well - actually - what is going to become them). the "proto pollux and proto hallux are positioned laterally. Over the next two weeks or so, there is a mild external rotation of the upper limb - which does not really change any story. However there is a radical internal rotation of the lower limb - such that what was at the back, is now at the front - the hallux becomes medial etc. That is why the flexors are posterior in the lower limb, but anterior in the upper limb - etc etc etc. It is almost a unifying theory of limb anatomy - analogous to quantum mechanics in physics. It brings together all sorts of apparently disconnected facts and unifies them into a single understanding.

    This is why, frankly, the terms medial and lateral do not adequately describe the lower limb - cranio-caudal (or better caudo-cranial) are more accurate. Perhaps even pre and post axial would be better.

    One can observe this in ontogeny - that is straight forward to observe - but then one should ask the big question: why? For this one has to delve into the phylogeny - where one finds that this is not a unique homo event - it occurs in all mammals - but not reptiles. It is thus one on the key skeletal modifications that occur at the reptilian-mammalian transition - the other obvious one being mandibular / middle ear ossicles, together with the associated myology.

    Raymond Dart, the finder of the first Australopethicus skull (The Taung child) was an Australian from close to Brisbane. We have just missed his annual memorial lecture at Griffith Uni. When he was on the staff at The University of Witwatersrand in the late 1920's, he was renown for standing at the front of the audience, raising his arm above his head, and dropping to the ground, ambulating like a croc. He would then rotate his limbs about to demonstrate this incredible transition in terms of locomotive efficiency.

    As I said above - this is not rocket science - just basic, very straightforward evolutionary anatomy.

    Hope this helps, Rob
     
    Last edited: Jun 2, 2016
  5. markjohconley

    markjohconley Well-Known Member

    Thanks Rob, great post. I am conducting a mini-survey atm with a local group of podiatrists to ascertain their knowledge of same.


    I didn't realise there were flexure creases posterior to the ankle till now, thanks



    PLANTARFLEXION = FLEXION at the ankle joint, that's clarified, thanks
    It is claimed in a few of the sites i've been searching that the terms 'plantarflexion' and 'dorsiflexion' were coined so as to make the situation less ambiguous; we're cheating sort of, why don't we use the anatomically 'more correct' terms? Are there any joints whose sagittal plane motion is not described as flexion / extension?
    Survey (n=3, 1 email, 1 phone call and myself) reveal all three thought wrongly.
    Not helped by numerous references such as, "Dorsiflexion refers to flexion at the ankle.." and diagrams such as attached below
     

    Attached Files:

  6. markjohconley

    markjohconley Well-Known Member

    On another webpage, not in the same class as PA, it was claimed by a poster, "It's easy, where are the flexors and extensors of the foot and ankle" I replied that unfortunately the muscles labeled with 'Extensor' and 'Flexor' that cross both ankle and metatarsophalangeal joints have been termed, "Flexor (or Extensor) Digitorum (or Hallucis) Longus" NOT "Flexor (or Extensor) ANKLE and Digitorum (or Hallucis) Longus" and just because a muscle flexes a joint doesn't necessitate it flexing any other joint it crosses eg Rectus Femoris, Biceps Femoris

    .................................................................................Then I added, "Come on, get with the times baby, catch up with the rest of humanity; forget tendon pathologies and tissue stiffness this is cutting edge, it's Evolutionary Anatomy 101"
     
  7. Rob Kidd

    Rob Kidd Well-Known Member

    Answer and comment interleaved:


     
  8. Rob Kidd

    Rob Kidd Well-Known Member

    As I understand it - though this was about a century before I was born, in recognition of the very highly evolved state of the ankle foot complex - and also in recognition of the apparent flexure creases on both articular surfaces, it was decided to use a changed terminology. That is, it essentially flexed in both directions. However, this ignored its evolutionary past - back to the amphibian, emerging from the sea about 450ma: at that point the front and back limbs were essentially the same, and have evolved down different paths since. Thus they are no longer the same - though leave a very clear path of where they have come from. The example that really rings home, is to look at the comparative morphology of the lateral plantar and ulnar nerves - now look at their deep branches. That is, in evolutionary speak, the median and ulnar nerves between them, equal the tibial nerve. The obvious difference is that the split into (the equivalence of) medial and lateral plantar nerves, takes place right back at the plexus.
     
  9. Rob Kidd

    Rob Kidd Well-Known Member

    As I understand it - though this was about a century before I was born, in recognition of the very highly evolved state of the ankle foot complex - and also in recognition of the apparent flexure creases on both articular surfaces, it was decided to use a changed terminology. That is, it essentially flexed in both directions. However, this ignored its evolutionary past - back to the amphibian, emerging from the sea about 450ma: at that point the front and back limbs were essentially the same, and have evolved down different paths since. Thus they are no longer the same - though leave a very clear path of where they have come from. The example that really rings home, is to look at the comparative morphology of the lateral plantar and ulnar nerves - now look at their deep branches. That is, in evolutionary speak, the median and ulnar nerves between them, equal the tibial nerve. The obvious difference is that the split into (the equivalence of) medial and lateral plantar nerves, takes place right back at the plexus.
     
  10. Rob Kidd

    Rob Kidd Well-Known Member

    Apologies for duplication - no idea why
     
  11. markjohconley

    markjohconley Well-Known Member

    Exactly
     
  12. Rob Kidd

    Rob Kidd Well-Known Member

    But of course true in those thigh muscles you mention - the hamstrings both extend the hip and flex the knee; the rectus flexes the hip and extends the knee. This send physios into paroxisms as clearly the muscle must undergo concentric and eccentric contraction at the same time; their solution - may well be right, is to invoke "co-contraction" where different parts of the muscle are doing different things at different times - its fast aproaching the too clever basket for me - a simple evolutionary biologist.
     
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