That's a good question. There's other pressure points as well
that should work just as well. For me, massaging between the
thumb/finger worked just as well and it's more accessible.
But yeah, that's a very good question. I mean you *should* be
able to access the muscle to get the knot out ; maybe you could
go at it from the opposite:
push your chest forward and shoulders back. then pull your
elbows straight down as if you were trying to shoot an aircraft
out of the sky with your chest.
[best way I can think of to describe the movement]
It's a stretch that seems to unravel the knot in that muscle
spot, at least for me.