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The difference between claws and nails

Discussion in 'General Issues and Discussion Forum' started by scotfoot, Aug 25, 2016.

  1. scotfoot

    scotfoot Active Member


    Members do not see these Ads. Sign Up.
    So whats the main difference between claws and fingernails/toenails ?

    In my opinion animals which posses claws use then to interact directly with the environment . For example they may be used for catching prey ,fighting , opening flesh so that eating prey species is made easier ,climbing , grooming etc .

    Nails (fingernails and toenails ) ,which are believed to have evolved from claws ,act indirectly with the environment.

    They are located on the dorsal aspect of the distal sections of the digits and by providing counter pressure they improve proprioception and ,in my opinion ,alter tissue displacement patterns when the plantar pads of the digits are subjected to pressure .

    I would argue that proprioception in the toes would be of particular value in preventing injury to the unshod foot from sharp objects like thorns and indeed that toenails may have had at least as important a role to play in the evolution of Homo Sapiens as fingernails .

    Gerry
     
  2. Rob Kidd

    Rob Kidd Well-Known Member

    In order to look at this further you need to think fourth dimensionally: length - bread - height - and time. Yes claws are essentially a plantar - or sort of plantar structure, and yes, nails are a dorsal structure. However, if one follows the embryology of the nail you will find that it starts its life as a plantar structure and migrates dorsally . There is no doubt whatsoever that nails are modified claws. to look further one should use comparative anatomy within and without primates. hooved animals such as cows, horses etc have yet another example of "nail structure". Try "Functional anatomy of the Vertebrates: an Evolutionary Perspective", 2001 by Liem, Bemis, Walker & Grande as a starting point. Page 224 illustrates this issue. Digit nails are incredibly important in fine, tactile discriminations such as picking up and object, shirt buttons etc. However in the foot this function is lost in favour of the bipedal habit (we have been around this tree before). Some primates - the tarsier comes to mind, have a mix of nails and claws - the claw is highly modified for looking for and extracting grubs out of trees. For what it is worth, as I stated before, in hominids, toes nails are a vestigial structure, and like other vestiges, can be a pain in the nethers when they go wrong - eg the appendix. Rob
     
  3. Lab Guy

    Lab Guy Well-Known Member

    IMO, the main difference between claws and toenails is that claws are necessary and toenails are not. I believe we would be much better off not having toenails and it would curb healthcare spending. I have permanently removed complete toenails on gymnasts, ballet dancers, runners and never heard of any complaints in regards to lack of proprioception or increased sensitivity.

    Steven
     
  4. scotfoot

    scotfoot Active Member

    Hi Rob
    You are quite right that the appendix used to be regarded as vestigial and indeed that is what I was taught as and undergraduate . However things move on and the appendix is now regarded as an important part of the immune system .

    ABSTRACT

    The vermiform appendix: not a useless organ.
    Zahid A1.
    Author information
    Abstract
    The appendix has often been seen more as a nuisance rather than an important part of the human anatomy. Early misconceptions have led to the indiscriminate removal of the appendix from the body. Long thought to be an evolutionary remnant of little significance to normal physiology, the appendix has more recently been identified as an important component of mammalian mucosal immune function, particularly B-lymphocyte-mediated immune responses and extrathymically derived T-lymphocytes. This structure helps in the proper movement and removal of waste matter in the digestive system, contains lymphatic vessels that regulate pathogens, and lastly, might even produce early defences that prevent deadly diseases. The appendix is one of the guardians of the internal environment of the body from the hostile external environment.
    ------------

    It has been shown that the sensitivity of the pad of a human finger is increased in the presence of counter pressure provided by a finger nail and I should imagine that the same system would be of benefit to the pads of the toes .

    My understanding is that the soft tissues of the hallux extend about 5-7 mm beyond the distal end of the distal phalanx . With a toenail in place this tissue is not easily vertically displaced but surely in the absence of a toenail this unsupported piece of soft tissue would be easily displaced if pressure is applied to it .

    Hi Steven
    I am not sure what you mean by "permanently removed ".

    Gerry
     
  5. Rob Kidd

    Rob Kidd Well-Known Member



    Would you care to quote the journal in which this was published? How it was referreed etc? Let us not forget that that the often claimed fact that the appendix has a perfectly
    formed mesentary (which may be important in the immuno process), merely says that the vestigial appendix has a vestigial mesentary.

    I await your reply re the journal, Rob
     
  6. scotfoot

    scotfoot Active Member

    Hi Robb
    This is the most recent paper I could find on the subject and ,as a review of the literature, is probably better informed than the paper I quoted previously .

    ABSTRACT

    Clin Exp Immunol. 2016 Jun 7. doi: 10.1111/cei.12821. [Epub ahead of print]



    The immunology of the vermiform appendix: a review of the literature.

    Kooij IA1, Sahami S2, Meijer SL3, Buskens CJ1, Te Velde AA1.



    Author information





    Abstract

    This literature review assesses the current knowledge about the immunological aspects of the vermiform appendix in health and disease. An essential part of its immunological function is the interaction with the intestinal bacteria, a trait shown to be preserved during its evolution. The existence of the appendiceal biofilm in particular has proved to have a beneficial effect for the entire gut. In assessing the influence of acute appendicitis and the importance of a normally functioning gut flora, however, multiple immunological aspects point towards the appendix as a priming site for ulcerative colitis. Describing the immunological and microbiotical changes in the appendix during acute and chronic inflammation of the appendix, this review suggests that this association becomes increasingly plausible. Sustained by the distinct composition of cells, molecules and microbiota, as well as by the ever more likely negative correlation between the appendix and ulcerative colitis, the idea of the appendix being a vestigial organ should therefore be discarded.

    ? 2016 British Society for Immunology.




    Gerry
     
  7. Lab Guy

    Lab Guy Well-Known Member

    "I am not sure what you mean by "permanently removed ".

    Gerry,

    It means the total nail plates are removed so they never grow back (most commonly the great toenails). The skin overlying the nail bed becomes thicker and almost resembles a nail. I have never heard or read that absence of toenails affect athletic performance in any way.

    Steven
     
  8. scotfoot

    scotfoot Active Member

    Hi Steven
    I wasn't sure whether you meant the removal of the nail or the nail and the germinal matrix . Thanks for the clarification .

    I have never seen a toe like this before but it is interesting that you describe the bodies reaction to this procedure as being one were "the skin overlying the nail bed becomes thicker and almost resembles a nail " .

    This would suggest to me that in the absence of a toenail the body tries to compensate for the nails loss in other ways which perhaps demonstrates the importance of the original nail .

    Gerry
     
  9. Rob Kidd

    Rob Kidd Well-Known Member

    But if removed the subject does not seem to come to harm - mind you, the same can be said about the spleen. It is certainly true that vestigial organs may resin some function. What is meant by the term is their original function has gone - such as the with the nictitating (?sp) eye lid. Rob
     
  10. wdd

    wdd Well-Known Member

    Dear Scotfoot 124,

    If proprioception is concerned with knowledge of where parts of the body are, relative to one another, in space and is facilitated by proprioceptors in muscles, tendons and joint capsules then it would seem to me that proprioception is of almost no value in avoiding standing on a thorn.

    To avoid standing on a thorn you would need to know that it's there before hand. This knowledge is most likely to come from your eyes and if you see it you don't need proprioception to avoid standing on it. You can just keep looking at the relationship of your foot to the thorn as you try to avoid it.

    Isn't that what people with tabes dorsalis do, ie watch where their feet are when walking, to avoid standing on things or tripping over things apart, of course, from lifting their feet too high and stamping?

    Apart from that nails would only come into play as ground contact is made and as far as proprioception and avoiding anything on the ground is concerned, to quote Carol King (I think), it's too late baby, yes it's too late.....

    Bill
     
  11. scotfoot

    scotfoot Active Member

    Hi Bill
    My user name is Scotfoot and I wondered where the 124 component came from ?

    My understanding is that proprioception has a cutaneous component .

    Re the Carol King quote you seem to me to be implying that an unshod foot with neuropathy is no more at risk of injury from sharp objects than a foot without neuropathy (which of course is not true ) .

    I note that you are a retired lecturer and accept that you are far more knowledgeable on the subject of podiatry than I am . I would be interested therefore to know if you regard the toenail as vestigial .

    Gerry

    Gerrard Farrell

    Glasgow
     
    Last edited: Aug 28, 2016
  12. wdd

    wdd Well-Known Member

     
  13. scotfoot

    scotfoot Active Member

    Hi Bill

    There can be a fair amount of cross over in the perception of afferent information from mechanoreceptors with large amounts of pressure at a point registering as pain but I can understand your objections to the example of the thorn .

    Would you accept that toenails help to provide information on the state of the unshod foot/substrate interaction and that this falls squarely into the bracket of proprioception ?

    For example if the forefoot of a running individual loses grip and begins to slide ,might the toenail by, applying counterpressure , aid the mechanorecptors in recognizing the pressure changes produced in the pulp of the toes .

    Intriguingly , you name " one of the important functions of finger nails " as being about attraction .

    Does that mean you know of others ? Please tell !

    Regards

    Gerry
     
  14. wdd

    wdd Well-Known Member

     
  15. Dieter Fellner

    Dieter Fellner Well-Known Member

    OMG! You're the one ... there are some individuals very unhappy about having nails removed and are clambering for a 'new' nail. Should we be more sensitive to this issue?

    This blog attracted almost 54,000 views.

    Is there a surgical procedure to replace damaged/missing toenails?


    https://podiatry.com/etalk/index.php?topicid=793#-1
     
  16. scotfoot

    scotfoot Active Member

    Hi Bill
    If you close your eyes and put your finger on the end of your nose then you know exactly where your finger is in relation to your nose through touch . This is not proprioception as I understand it .
    If you bite down hard on something then the amount of force being used will be sensed by the periodontal ligament . This is proprioception .

    Similarly the pressure change being sensed within the toe pulp during a slip is proprioceptive . The pressure within the toe pulp is an internal measurement .

    Gerry
     
  17. wdd

    wdd Well-Known Member

    Hi Gerry,

    At least one part of the difficulty here is that we are each using the word proprioception in a different way.

    I gave my definition in my first post, ie. knowledge of the position of parts of the body relative to one another.

    If you could give me your definition of proprioception we would at least be on the same page.

     
  18. scotfoot

    scotfoot Active Member

    Hi Bill


    My definition of proprioception is that it is primarily about knowledge of position in space but also includes knowledge of pressure being applied .

    For example a child suffering from proprioceptive deficits might continually break toys ,or snap crayons without meaning to .

    Gerry
     
  19. wdd

    wdd Well-Known Member

    Hi Gerry,

    I've just updated my knowledge and understanding of proprioception and without negating my own definition I need to add on a skin contribution and a sense of force and effort. I now see where you are coming from and agree with you.

    Plantar sensation does contribute to proprioception and to the extent that nail plates increase that sensitivity they contribute to proprioception.

    Bill

    PS I wrote the above before reading your last post. I think we are now on the same page.
     
  20. wdd

    wdd Well-Known Member

    [QUOTE


    Intriguingly , you name " one of the important functions of finger nails " as being about attraction .

    Does that mean you know of others ? Please tell !QUOTE]

    The attraction thing included toe nails. Finger nails as a first check and toe nails as final check. In retrospect I think that's worth two?

    I was basing my second major function on something I read within the last twenty years. I am sure it was online and I am pretty sure it was a PhD thesis. I've tried to find it again online within the last couple of days but without success. At the time I dismissed it as nonsense but now that I've updated my knowledge and understanding of proprioception and the skins contribution it doesn't seem so far fetched, in fact it almost seems like genius.

    As I remember it (I only read the summary) the central idea was that the toenail sulcii contained an iron composite particle that acted as a magnet and was influenced by the earth's magnetic field. The toe nail sulcii somehow created a line of these magnetic particles allowing a 'fine tuning' of not only the relative position of parts of the body to one another but also to the earth. The sensitivity of the system was determined by the direction and presence of the toe nail. I think the implication was that it was the presence of the toe nail that attracted the magnetite and the direction of the lateral borders of the nail that lined up the particles.

    I'd heard about this in birds and some animals but I thought that the magnetoreceptors had to be situated in the brain or the eye. Now, given the skins association with proprioception I can see how this system could work. That is it might feedback into the proprioceptors in muscles in a similar way to skin. It could almost mean that we contain our own gps system? The Mind boggles. I've no idea how being cover with socks and shoes, etc would affect it but it certainly elevates the function of the humble toe nail to a new level.

    I think there was also some suggestion that this feature was not shared with finger nails because the rapid and large changes in orientation of the hand would have required too much computing power.

    Maybe someone else out there can add something to this?

    Bill
     
  21. wdd

    wdd Well-Known Member

    That negates a large part of the value of podiatry? You are spending a lot of your energy on something that has 'no' intrinsic value. If you could somehow incorporate that idea into a religious philosophy backed up by a health warning, think foreskins, I would imagine that it might be possible to create a world where toe nails were removed at birth. In fact why not go for a job lot and go for toe nails, foreskin, appendix, tonsils, adenoids, spleen, ?etc all at the same time. That would reduce the burden on the NHS.

    Have I not read somewhere that we Only use ten percent of our brains?

    "Off with ninety percent of his head".

    Seriously, the difference in proprioception with or without toe nail is likely to be shrinkingly small and would be unlikely to create any conscious recognition of loss of proprioception.

    One possible way to measure the effects of the removal of nail plate/s with matrix sterilisation on performance (dance, athletic, etc) but one that would require big numbers of participants is to compare ultimate levels of performance between the two groups, that is between those who have had toe nail removal and matrix sterilisation and those who haven't. In fact you might want to include a third group, those who had nail plate removal without matrix sterilisation. There we go, that's a lifetimes work for someone!

    I wonder if I might change the direction of this thread a little but without moving too far off topic.

    In thickened human toe nails we are told that they grow more slowly and I for one have accepted that without thought because it's obvious that they advance more slowly and require cutting less frequently but that's only a three dimensional measure of their growth.

    In terms of volume, is there a volume rate of production difference between unthickened and thickened toe nails, ie are the changes largely/totally of the relationship of one cell to another rather than in the rate of cell production and the number of cells produced?

    Bill
     
  22. scotfoot

    scotfoot Active Member

    Quote -
    "Seriously, the difference in proprioception with or without toe nail is likely to be shrinkingly small and would be unlikely to create any conscious recognition of loss of proprioception. "

    And yet Bill, fingernails have been shown to create a conscious effect on the recognition of proprioception so why not toenails .

    The cutaneous component of the forefoot area is packed with sensory nerve endings so why not potentiate them ?

    Re volume I am afraid I can contribute nothing in this area .
    Gerry
     
  23. wdd

    wdd Well-Known Member

    Hi Gerry,

    You're right. I might be manifesting the same thing I am arguing against. I am arguing against the idea of the toe nail having no value and here I am minimising its value when I have absolutely no idea of the size of the effect.

    I introduced the thickened toe nail because I often think that more and more mental effort is put into the esoteric while none is put into the stuff of everyday podiatric life, such as the thickened toe nail.

    When I ask myself why the thickened toe nail grows the way it does my answer is no more detailed than, damage to the matrix. I have no mental picture of what's going on say at the microscopic level.

    I asked myself if there is even any sense in the idea of selective matrix destruction to produce a thinner but possibly slower growing nail but my lack of knowledge of the details of the dynamics of growth of the naile plate in health and disease means that I haven't the faintest idea and the cynic in me thinks that there must be something fundamentally wrong with a profession which cannot answer or whose focus is so strongly diverted away from its central activities. Wow, that must be the longest sentence I have ever written!

    Bill
     
  24. scotfoot

    scotfoot Active Member

    Hi Bill
    I have been trying to find a study that looks into changes in plantar pressure distribution, that occur during gait , following the complete permanent removal of the nail from the hallux , but cannot find any specific information .
    Since removing the nail would remove a source of counter pressure I feel it might produce significant plantar pressure distribution changes .
    Are you aware of any relevant studies ?

    Kind regards

    Gerry
     
  25. efuller

    efuller MVP

    The difference between the toe with, and a toe without the nail would be the weight of the toenail. (A very small amount of force compared to the forces seen acting on the toe.) The nail does not apply counter pressure because it is attached to the toe. What creates ground reaction force on the toe is the weight of the body and structures that create a plantar flexion moment on the bones of the toe. (plantar fascia, long and short flexor tendons.)

    Eric
     
  26. scotfoot

    scotfoot Active Member

    Hi Eric
    Just came across a related paper from which the following quote is taken .

    "Toenails contribute to pedal biomechanics. During daily life, nails are constantly exposed to physical stimuli such as counter pressure and shear force. These mechanical forces may therefore play a marked role in nail configuration and participate in the development of nail deformities."

    Here is a link to the paper --
    Foot loading is different in people with and without pincer nails: a case ...

    https://www.ncbi.nlm.nih.gov › NCBI › Literature › PubMed Central (PMC)
    by H Sano - ‎2015 - ‎Cited by 1 - ‎Related articles
    Published online 2015 Aug 19. doi: 10.1186/s13047-015-0100-y ... In total, 12 bilateral pincer nailcases (24 affected feet) and 12 age- and ... daily life, nails are constantly exposed to physical stimuli such as counter pressure and shear force.
     
  27. wdd

    wdd Well-Known Member

    Hi Eric,

    I think Gerry is focusing on the possible effects, on plantar pressure, resulting from the propreoceptive feedback differences between an absent and present toe nail on those "structures that create plantar flexion moment on the bones of the foot" and possibly other structures?

    Bill
     
  28. scotfoot

    scotfoot Active Member

    Hi Bill
    It has been suggested that the counter pressure which toenails provide not only improves proprioception but also alters tissue displacement patterns when the plantar pads of the digits are subjected to pressure .

    A fairly recent paper , Lopez et al 2015 (1 ) discusses toenail function and anatomy in detail and I have include some quotes from this below .
    Quotes -
    "Namely ,the nail is functionally integrated with the musculoskeletal system "

    "The most important function of the toe nail is in its propriocepive role .its protection of the digit ,and in the control of the toe pulp "

    I have been trying to find information on what happens to proprioception and pulpal control after the nail of a hallux has been completely and permanently removed .

    ( 1)

    Anatomic relationship of the proximal nail matrix to the extensor ... - NCBI


    https://www.ncbi.nlm.nih.gov/pubmed/25807869
    by LP Palomo - ‎2015 - ‎Related articles
    23 Mar 2015 - Anatomic relationship of the proximal nail matrix to the extensorhallucis longus tendon insertion. Palomo López P(1), Becerro de Bengoa ...
     
  29. scotfoot

    scotfoot Active Member

    Hi Bill
    Bringing further grist to the mill ,this -

    Plast Reconstr Surg Glob Open. 2015 Mar 6;3(2):e311. doi: 10.1097/GOX.0000000000000220. eCollection 2015.
    A novel nonsurgical treatment for pincer nail that involves mechanical force control.

    Sano H1, Ogawa R1.
    Author information

    Abstract


    We hypothesize that nails have an automatic curvature feature and that their flat shape is maintained by the daily upward mechanical forces from the finger/toe pad. Thus, nail deformities, such as pincer nail, spoon nail, and koilonychias, may be caused by an imbalance between these forces and can be treated by controlling these forces. Here, we report the case of a 55-year-old man whose severe pincer nail was effectively treated by thinning the nail, which reduced the automatic curvature force. This is the first report to show that pincer nail can be treated by a nonsurgical method that reduces the automatic curvature force, thus obviating the need for surgery. This supports the notion that mechanical stimulus-based treatments have high therapeutic potential for nail deformities.
     
  30. efuller

    efuller MVP

    If pincer nails are caused by lack of pressure on pads of fingers/ toes, you would expect a lot more pincer fingers than toes. The pressures on fingers are less frequent, and my sense is less force than on the toes.

    Eric
     
  31. scotfoot

    scotfoot Active Member

    Hi Eric
    In the study above (Lopez et al 2015 (1 ) ) , it was found that the anatomy around and securing the toenail was different than that found in around the finger nail . I would hazard a guess that these anatomical differences may have evolved to cope with the additional tissue pressures generated by bipedalism on the digits of the lower extremity .
    Perhaps because of the anatomical differences , the fingernails need less pressure to maintain a healthy shape than the toenails do .

    Gerry
     
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