\item$V$ is the potential relative to the ECM $[mV]$
\item$a$ is the cable radius \todo{units}
\item$c_m$ is the {specific membrane capacitance}, approximately the same for all neurons $\approx10~nF/mm^2$. Related to \emph{membrane capacitance}$C_m$ by the relationship $C_m=c_{m}A$, where $A$ is the surface area of the cell.
\item$i_m$ is the membrane current \todo{units}
\item$r_L$ is intracellular resistivity, typical value $1~k\Omega$