A recording console has two types of signal source. One is from the microphone and line inputs. The other is from the already-recorded signals on the multitrack tape. To record overdubs, these must be mixed together for the monitor mix and headphone foldback.
An inline monitoring console incorporates the return signals from the multitrack within the channel modules.
Therefore each channel will have a mic/line input, and an input for one track of the multitrack. These signal paths are separate. The input signal will go to a small fader where its level is controlled for sending to the multitrack. The monitor signal from the multitrack will go to the large fader to create a monitor mix.
It is important to realize that you might be using channel 17 to record a vocal overdub to track 4 of the multitrack. The monitor signal would come back to the monitor section of channel 4.
Usually, the channel's facilities such as EQ, dynamics, aux sends etc. can be shared between the input signal path and the monitor signal path.