I was interested to see the plural of scrotum as scrota. Not surprised, as this is the usual plural form for many words (singular) ending in -um. I have a medical history but had never heard the word used. Possibly, because I generally only ever dealt with one scrotum at a time!!!
So, scrota is a common word (is it?), but, two other medical terms come to mind that are classed rare, namely, medial (toward the middle or medial ligament) and atrial (of the atria or atrial fibrillation). It seems to me that the latter two words are probably more used than the scrota. How many sports identities suffer a medial ligament tear or how many millions of individuals, literally, are treated for atrial fibrillation? Therefore, should not (if I'm correct) both medial and atrial be deemed common?