Commentary for Bekhorot 7:4

גופו גדול מיבריו – the measurement of his body is larger than appropriate according to the measurement of the remainder of his limbs, as for example, his hands, and his feet and his legs.

One whose eyes are as large as a calf's or as small as those of a goose;
Or whose body is [unduly] large for his limbs, [unduly] small for his limbs; or whose nose is [unduly] large for his limbs, or whose nose is [unduly] small for his limbs;
A tzimem and a zimea. What is tzimea? One whose ears are very small. What is tzimem? One whose ears resemble a sponge.
If some of a person’s limbs, nose or ears are either too large or too small, the person cannot serve as a priest. Basically, we can summarize that the rabbis thought the priest should look normal and have normal proportions.
I might want to add at this point, that in the ancient world it was thought that a strange outer appearance reflects a problematic inner self, perhaps lack of morality or lack of intelligence. While today we know that this is often, and perhaps usually not so, we should, I believe, acknowledge, that it is sometimes so, and that sometimes, mental problems accompany physical defects. It is not surprising that people in the pre-modern world, including rabbis, took this as the rule. Thankfully, though, we now understand better that, as they say, “one should not judge a book by its cover.”
The mishnah is pretty straightforward, so I will explain only where I feel necessary.
Section three: The only section that probably needs explanation is the “tzimem” whose ears resemble a sponge. According to Rashi, this means that they are shrunken and closed. Maimonides interprets it to mean large and swollen. In either case, they are deformed.

חוטמו גדול – the measurement of his nose is like the measurement of a small finger of his hand. But if it was long than this or shorter than this, it is a blemish.

דומות לספוג – shrunk and closed up.