  The KASCADE-Grande Muon Tracking Detector enables with high accuracy the
measurement of directions of EAS muons with energy above 0.8 GeV and up to 700
m distance from the shower centre. Reconstructed muon tracks are used to
investigate muon pseudorapidity (eta) distributions. These distributions are
nearly identical to the pseudorapidity distributions of their parent mesons
produced in hadronic interactions. Comparison of the eta distributions from
measured and simulated showers can be used to test the quality of the high
energy hadronic interaction models. In this context a comparison of the
QGSJet-II-2 and QGSJet-II-4 model will be shown. The pseudorapidity
distributions reflect the longitudinal development of EAS and, as such, are
sensitive to the mass of the cosmic rays primary particles. With various
parameters of the eta distribution, obtained from the MTD data, it is possible
to calculate the mean logarithmic mass of CRs. The results of the <lnA>
analysis in the primary energy range 10^{16} eV - 10^{17} eV with the 1st
quartile (Q1) of eta distribution will be presented.
