Taking symbolic variables out of txt file and making a matrix

I have a txt file containing following characters.

theta1 , l1 and others are symbolic variables.( Don't mind about it)

 M=[theta1 + (l1^2*m1)/4 + l1^2*m2 (l1*l2*m2*cos(fi1 - fi2))/2 ; 
     (l1*l2*m2*cos(fi1 - fi2))/2 theta2 + (l2^2*m2)/4 ]

I need to take it out and make it a symbolic matrix. As you can see txt file is already fine for making matrix but I don't want to copy paste the whole thing to script, I rather want to do it automatically.

fid = fopen('a.txt');
    MMatrix=textscan(fid,'%s');
    fclose(fid);

I tried the code above but it turn out to be not useful. What do you think is the way to copy the whole thing and use it for matrix making?