Extended quark distribution functions are presented obtained by fitting a large amount of experi-mental data of the ι-A DIS process on the basis of an improved nuclear density model. The experimental data of ι-A DIS processes with A≥ 3 in the region 0.0010 ≤ x ≤ 0.9500 are quite satisfactorily described by using the extended formulae. Our knowledge of the influence of nuclear matter on the quark distributions is deepened.