  Motivated by recent theoretical and experimental interest in the spin and
orbital angular momenta of elastic waves, we revisit canonical wave momentum,
spin, and orbital angular momentum in isotropic elastic media. We show that
these quantities are described by simple universal expressions, which differ
from the results of [G. J. Chaplain et al., Phys. Rev. Lett. 128, 064301
(2022)] and do not require separation of the longitudinal and transverse parts
of the wavefield. For cylindrical elastic modes, the normalized z-component of
the total (spin+orbital) angular momentum is quantized and equals the azimuthal
quantum number of the mode, while the orbital and spin parts are not quantized
due to the spin-orbit geometric-phase effects. In contrast to the claims of the
above article, longitudinal, transverse, and `hybrid' contributions to the
angular momenta are equally important and cannot be neglected. As another
application of the general formalism, we calculate the transverse spin angular
momentum of a surface Rayleigh wave.
