traj{1} %that's your first matrix
traj{2} %that's your 2nd matrix, etc....
Since each matrix is the same size (4x4), if you wanted to combine the matrices stored in each element of the cell array into one big matrix, you could concatenate them horizontally
cell2mat(traj) %assumes traj has size 1 x n
or concatenate them vertically
cell2mat(traj') %assumes traj has size 1 x n
or you could conver them to a 4 x 4 x 10 array
reshape(cell2mat(traj),4,4,10) %assumes traj has size 1 x n
or it might be best to just leave them in the cell array depending on how you will be using those data.
