TEN BY THREE

There are only ten body parts with three letters:

1 leg
2 ear
3 rib
4 arm
5 hip
6 gum
7 eye
8 jaw
9 toe
10 lip

Of course, there are many slang ones too, and ones that are not really body 'parts', eg gut, fat. There are contractions (eg lid) and pedantic obscurities (eg rods in the eye), but it's more or less just the ten. A quiz night favourite (see also: what's on the obverse of a two pence piece; in which town is St Edmund buried; which Scottish football team is mentioned in the Bible etc).