Rav Yehudah said: Two small ramps branched off from the main ramp, by which one (on the west side) turned to the base and one (on the east side) to the ledge, and these were also separated from the altar by a hairsbreadth, because it is written: around.
HaRav Dovid Meyers, author of the fabulous sefer on the construction of the Mishkan, Meleches HaMishkan V’Kailav, notes: This is referring to the altar in the Beis HaMikdash. It is logical to assume that there would also be one to the ledge in the Mishkan if the ledge in the Mishkan was for the Kohanim to walk upon. According to Rashi in Chumash there was no ledge for the Kohanim to walk on in the Mishkan, so there was no need for a small ramp to the ledge. There are commentators that maintain that there was a ledge for the Kohanim to walk on in the Mishkan (page 234), so according to them there was a need for a small ramp to the ledge.
Regarding if in the Mishkan there was a small ramp to the base, according to what Shitah Mekubetzes (letter 12) that the purpose of the small ramp to the base was because if the Kohen would have to go down the ramp and then go to the base, the blood might coagulate and become unfit for sprinkling, it would seem that there should also be one in the Mishkan. Even though it would seem that the ramp in the Mishkan was a little shorter than the ramp in the Beis HaMikdash, it is not logical to say that since the ramp in the Mishkan was a few amos shorter than the ramp in the Beis HaMikdash, there would be no concern that the blood would coagulate. According to what we have written, it seems that there was only one small ramp in the Mishkan,