How to compare multiple polynomials in MATLAB?
Based on what you share, this is the best answer I can give.
I see two methods:

Method #1,

Instead of making N polynomials (if N is the number of ribs), you could fit a curve for all the ribs at once. Of course, for that, you will need to have a common (0,0) coordinate, in other word, stack them one over the other on your image. Since you are able to make a distinction between the ribs, that means that you can already isolate them, so that shouldn't be an issue. 

Or if you prefer, you can generate a new cloud of points with the polynomials you already found. 

coeffs = [0.0010126, -1.5981, 1074.8; 0.0024871, -3.3327, 1866.3];
x = linspace(0,1000,1000); % fictives points
merged_x = [x x];
merged_y = [ polyval(coeffs(1,:), x), polyval(coeffs(2,:),x)];
coeffs_final = polyfit(merged_x, merged_y, 2);
figure
hold on
plot(polyval(coeffs(1,:), x), 'red')
plot(polyval(coeffs(2,:), x), 'blue')
plot(polyval(coeffs_final, x), 'black')




Method #2

You could fit 3 polynomials to find the values of the coefficient you already have found. If we take the first polynomial you provided, then 
$a_2=0.0010126$ $a_1=-1.5981$ $a_0=1074.8$

You could fit a curve that would follow all $a_2$, another for all $a_1$, and same for all $a_0$. This would yield 9 new coefficients (3 polynomials) that will allow you to find your polynomials based on the rib position.

Here's an example

coeffs = [ 0.0010126     -1.5981       1074.8;
    0.0024871     -3.3327       1866.3;
 0.002662      -3.7067       1631.4;
 0.0025574     -4.5129       2148.4;
 0.002114      -3.3457       2195.6;
 0.0015383     -2.6023       1682.9 ];

x = linspace(0,1000,1000); %fictive value
ribs_count = size(coeffs, 1);
a2 = polyfit(1:ribs_count, coeffs(:,1)', 2); % careful to the ' symbol that transpose the column into a row
a1 = polyfit(1:ribs_count, coeffs(:,2)', 2);
a0 = polyfit(1:ribs_count, coeffs(:,3)', 2);

figure
for rib=1:ribs_count
    subplot(6,1,rib);
    hold on
    new_coeffs = [polyval(a2,rib), polyval(a1,rib), polyval(a0,rib)];
    plot(x, polyval(new_coeffs, x), 'red')
    plot(x, polyval(coeffs(rib,:), x), 'blue')
end