According to this the Core did proceed down to an antimatter souce.
Produced by Paramount from this illistrator.
Strictly speaking, it proceeded FROM an antimatter source. The top of the intermix--the impulse deflection crystal--is not a deuterium injector, it's a transfer point between the intermix chamber and the impulse engines. As Probert explained once, the entire purpose of the intermix chamber is to connect the matter/antimatter reactor to all the engine parts that will make use of its power. Those same schematics also show an auxiliary fusion generator on S-Deck (feeding into the intermix chamber incase the main reactor fails) and likewise show the reactor itself on U-Deck; THAT reactor at the bottom of the shaft IS the warp core. If you don't believe me, go to sheet nine and read the synopsis for U-Deck where it says:
U-Deck is also known as the reactor deck. The reactor bay holds the main matter/antimatter reactor, twenty four antimatter storage bottles, and the bottom of vertical intermix shaft Engineering Core. Aft of the reactor bay is the retractable tractor beam, flanked by two bussard collectors, which gather interstellar hydrogen, process it, and refil all internal hydrogen tanks.
Apart from basically placing the ramscoop in the main deflector dish (as I always thought it should be) this would also mean the ship's deuterium stores are small to non-existence since at warp speed the ship runs almost entirely on material gathered from the interstellar medium.
Come to think of it, CTM, that's a tricky choice to make once you get to work on the navigational deflector. Especially considering your designs are based on this blueprint, if you put the ramscoop in the deflector, you'd have to flesh out some kind of plumbing system in the front of the engineering hull to route deuterium to where it needs to go.
I've often wondered about this... the apparent lack of "TOS-ish" bussard collectors on the TMP ship nacelles may have been due to the determination that the deflector, on its own, was able to collect enough material to support the ship's needs.
For the TOS ship, I generally assume that the dish doesn't have any collection capabilities. For TNG-era ships, they've gone back to having a collector on each nacelle (excepting for one "First Contact Armada" ship which seems to have them on the main hull, albeit in line with the nacelles).
But the feasibility of having the deflector/collector be coaxial seems too obvious not to at least give a little attention to.
Perhaps the "ring of lights" around the dish on the TMP ship are actually the hydrogen intakes?
I just find the "black slat" front end of the TMP nacelles to be... well... disappointing and dull. Then again, I've never been a big fan of the TMP engines, so I'm a bit biased there.