Maseches Tamid, chapter 4, describes how the lamb offered each morning as a korban tamid was butchered. It says:
He arrived at the left side.… The spine was with it and the spleen was suspended from it. It was large, but they called the right [side] "large" because the liver was suspended from it.
Note that the Rosh clarifies that the left side was larger because it included the spine.
Why did the liver made them call the small (right) side "large"?
I've found two answers to my question above. However, I'm unsatisfied with each of them, as I'll explain. I seek alternatives to the following answers and/or solutions to the problems I have with them.
The commentary printed with the Bavli explains that "the left side was heavier [than the right], but they called the right [side] 'large' because the liver was suspended from it and the liver is not part of the side. Since something not part of the side was suspended from it, it was called 'large'."
Makes sense to me, but: Is the spleen a part of the side more than the liver is a part of the side? (I can't find good pictures online.) If not, how do we understand this commentary?
The Raavad explains that the right side was in fact heavier, because the liver was heavier than the spine and spleen combined.
But: What, then, does the mishna mean when it says the left side was large?