Conformation Showing > Mr. Donald asked me a difficult question (115 replies)
by Ibrahim on 15 June 2012 - 11:14
|Let us pay a closer look at the shoulder itself|
Any triangle has a sum of 180 degree, this is a mathmetical rule.
The line you see seperating the big shoulder triangle into 2 smaller triangles is the horizontal. Where it meets the imaginary vertical (the 27.25 cm line) it makes an angle of 90 degrees up and 90 degreed down, this is also a mathematical rule ( angle between the horizontal and the vertical is 90 degrees.
Looking at top small triangle and since we're assuming the shoulder angle to be 45 degrees then the remaining third angle (top one) is = 180 - (90 + 45) = 45 degrees.
Looking at bottom triangle and since we're assuming the front upper arm is 45 degrees then the remaining third angle (the bottom one) is= 180 - (90 + 45) = 45 degrees.
After drawing the two 45 degree angles the software (autocad) gives us the shoulder length and front upper arm length to be equal and each 19.2687 cms in this dog's case (65 cms high and chest depth 45% from total height at withers, imaginary vertical line connection the mid point of top of shoulder blade and elbow joint where front upper arm rests in the cavity at top of front leg.)
This (the two lengths being equal is correct and a rule in a triangle of two 45 degree angles and third one 90 degrees.
For more details of properties of this angle see herehttp://www.mathopenref.com/triangle454590.html
by Ibrahim on 15 June 2012 - 11:24
|The sum of shoulder bones in this case is 38.5374 cms and the sum of shoulder angles is 90 degrees and its corresponding reach is 44.37 cms|
by Ibrahim on 15 June 2012 - 11:27
|Let us look at the more real ideal shoulder of 45 degree shoulder and 53 degree front upper arm angle|
by Ibrahim on 15 June 2012 - 11:36
|Let us have a closer look at the shoulder itself|
As we did before and after setting the sfront upper arm angle at 53 degrees the thirs (bottom) angle is calculated too be 37 degrees, actually the software (autocad gives it or makes it automatically). Please note as the front upper arm angle becomes bigger this third angle (in this case 37 degrees) becomes smaller causing the direction that front upper arm goes from elbow joint towards the shoulder joint steeper. Just to give you a smile in the beginnings when a member said a dog had a steeper front upper arm I was confused what that exactly meant, well to those who are still confused at this term that is what it actually means, bottom angle lesser more steep the front upper arm is, lol.
by Ibrahim on 15 June 2012 - 11:46
|The sum of shoulder bones in this case is 36 cms, a decrease of 1.5 cms or 3.9%, |
And here is the corresponding reach 43.2 cms, with a decrease of 1.17 or 2.8%. Maybe that is why some are still longing for the 90 degree shoulder!!!!!!!!
by Ibrahim on 15 June 2012 - 11:58
|What do we learn from the above, ( but not final till we see more examples and more shoulder angles and lengths combinations):|
The bigger the front upper arm angle
1. The shorter is the shoulder blade
2. The bigger is the sum of total shoulder angle
2. The shorter is the front reach
3. The steeper is the front upper arm
4. The less is the sum of shoulder bones, and therefore the less is the sum of front assembly bones
by Ibrahim on 15 June 2012 - 12:06
|Also we learn as long as the shoulder blade remains at good angle of 45 degrees, the longer the shoulder blade is the better (less angle) angle we get in the front upper arm, but let us wait till all possible combinations in the shoulder are demonstrated to see if this hold correct and upto which point.|
by Ibrahim on 15 June 2012 - 12:17
|Also we learn from these two cases that the increase of front reach is due to the increase in the length of the shoulder blade (in the first case of 45 degrees of shoulder blade and front upper arm) because when the front upper arm angle got bigger, 53 degrees, the front upper arm length got slightly bigger. So what really matterred is the increase of shoulder blade length.|
But again let's wait and see the other combinations and what holds true for all demos.
by Ibrahim on 15 June 2012 - 12:20
|Also we learn that the longer the sum of shoulder bones the better the front reach,|
Also we learn the less the sum of shoulder angles the better the reach is,
again we'll see other combinations and decide.
by Ibrahim on 15 June 2012 - 12:48
|Ah, one more point we learn here, you see in case of 45 degrees both the shoulder and front upper arm angles the shoulder blade and front upper length lengths are equal and the proportion is 1:1, so we learn that the less the proportion the better is the front reach, but again let us wait and see if this hold true in other shoulder combinations.|
by Ibrahim on 15 June 2012 - 12:54
|Let us see this theoretical combination where the shoulder blade is less than 45 degrees and front upper arm angle remains the same.|
Dog in standing, shoulder angle is 35 (maybe not possible in reality but for learning purpose).
by Ibrahim on 15 June 2012 - 13:05
|Let us look closely at the shoulder of this case, shoulder angle 35 degrees and compare the outcome to the ideal case of shoulder angles 45 and 53 degrees.|
Now the sum of angles of shoulder angles is 88 degrees. The sum of bone lengths is 38.7215 cms with an increase of 2.7 cms or 7.5%, also front upper arm length got bigger and shoulder blade length got a little smaller.
by Ibrahim on 15 June 2012 - 13:08
|Let us see what happens to the reach, it got better 44.94 cms with an increase of 1.7 cms or 3.9%.|
by Ibrahim on 15 June 2012 - 13:18
|What still hold correct|
As the shoulder angle gets smaller, front upper arm remaining at ideal of 53 degrees, the sum of shoulder angles becomes less, the shoulder blade length gets very slightly shorter, front upper arm length increases valuably, sum of shoulder bones increase valuably, the front reach increases valuably.
Proportion of shoulder blade length to front upper arm length is 1:1.36, we notice that the proportion increased while still the front reach incresed so the assuption or deduction that the less the proportion the better the front reach is wrong.
Still holds correct
Less shoulder angle better reach
Less shoulder sum of angles better reach
Less shoulder angles more sum of bone lengths
More shoulder bone lengths, more bone lengths of front assembly, better front reach
by Ibrahim on 15 June 2012 - 13:31
|I see it is too difficult for me to deal with various analysis elements, so I will only comment on the most important effects and later make charts of results for each element of interest and see the common relation (trend).|
by Ibrahim on 16 June 2012 - 18:14
|Let us see what happens when the shoulder angle increases.|
Standing, shoulder angle 50, front upper arm remaining 53
by Ibrahim on 16 June 2012 - 18:15
|Let us look closely at the shoulder|
by Ibrahim on 16 June 2012 - 18:15
by Ibrahim on 16 June 2012 - 18:23
|Looking at the shoulder the sum of shoulder bones is 34.7557 with a decrease of 1.244 cms or 3.45% , comparing to the ideal shoulder where the shoulder angle is 45 and front upper arm angle is 53 degrees, the sum of shoulder angles is 103. The ratio between the length of shoulder blade to the front upper arm length is 1: 1.06.|
The front reach decreased 0.95 cm or 2.2%.
by Ibrahim on 16 June 2012 - 18:31
|Let us see what happens when the shoulder angle is bigger|
Standing, shoulder angle 55, front upper arm angle remaining 53 degree