Let the point \( P \) of the focal chord \( PQ \) of the parabola \( y^{2}=16x \) be \( (1,-4) \). If the focus of the parabola divides the chord \( PQ \) in the ratio \( m:n \), \( \gcd(m,n)=1 \), then \( m^{2}+n^{2} \) is equal to:
\( 17 \)
\( 37 \)
\( 10 \)
\( 26 \)