  We present a detailed study of the lowest-lying ${\frac{1}{2}}^-$ and
${\frac{3}{2}}^-$ $\Lambda_{Q}$ resonances both in the heavy quark (bottom and
charm) and the strange sectors. We have paid special attention to the interplay
between the constituent quark-model and chiral baryon-meson degrees of freedom,
which are coupled using a unitarized scheme consistent with leading-order heavy
quark symmetries. We show that the $\Lambda_b(5912)$ [$J^P=1/2^-$],
$\Lambda_b(5920)$ [$J^P=3/2^-$] and the $\Lambda_c(2625)$ [$J^P=3/2^-$], and
the $\Lambda(1520)$ [$J^P=3/2^-$] admitting larger breaking corrections, are
heavy-quark spin-flavor siblings. They can be seen as dressed quark-model
states with $\Sigma_{Q}^{(*)}\pi$ molecular components of the order of 30\%.
The ${J^P=\frac{1}{2}}^-$ $\Lambda_c(2595)$ has, however, a higher molecular
probability of at least $50$\%, and even values greater than 70\% can be easily
accommodated. This is because it is located almost on top of the threshold of
the $\Sigma_c\pi$ pair, which largely influences its properties. Although the
light degrees of freedom in this resonance would be coupled to spin-parity
$1^-$ as in the $\Lambda_b(5912)$, $\Lambda_b(5920)$ and $\Lambda_c(2625)$, the
$\Lambda_c(2595)$ should not be considered as a heavy-quark spin-flavor partner
of the former ones. We also show that the $\Lambda(1405)$ chiral two-pole
pattern does not have analogs in the $\frac{1}{2}^-$ charmed and bottomed
sectors, because the $ND^{(*)}$ and $N\overline{B}{}^{(*)} $ channels do not
play for heavy quarks the decisive role that the $N \overline{K}$ does in the
strange sector, and the notable influence of the bare quark-model states for
the charm and bottom resonances. Finally, we predict the existence of two
$\Lambda_b(6070)$ and two $\Lambda_c(2765)$ heavy-quark spin and flavor sibling
odd parity states.
