  An analysis of the angular distribution of the decay $\Lambda_b^0 \rightarrow
\Lambda \mu^{+} \mu^{-}$ is presented, using data collected with the LHCb
detector between 2011 and 2016 and corresponding to an integrated luminosity of
approximately $5\,fb^{-1}$. Angular observables are determined using a moment
analysis of the angular distribution at low hadronic recoil, corresponding to
the dimuon invariant mass squared range $15 < q^{2} < 20\, GeV^2/c^4$. The full
basis of observables is measured for the first time. The lepton-side,
hadron-side and combined forward-backward asymmetries of the decay are
determined to be \begin{align} A_{FB}^{l} & = -0.39 \pm 0.04\,\rm{stat} \pm
0.01\, \rm{syst}, \nonumber\\ A_{FB}^{h} & = -0.30 \pm 0.05\,\rm{stat} \pm
0.02\, \rm{syst}, \nonumber\\ A_{FB}^{lh} & = +0.25 \pm 0.04\,\rm{stat} \pm
0.01\, \rm{syst}. \nonumber \end{align} The measurements are consistent with
Standard Model predictions.
