Sat, 07 Oct 2006
The fibula is the small bone in the lower leg; it's named for the Latin fibula, which is a kind of Roman safety pin. The other leg bone, the tibia, is much bigger; that's the frame of the pin, and the fibula makes the thin sharp part.
"Pelvis" is Latin for "basin". The pelvis is made of four bones: the sacrum, the coccyx, and the left and right os innominata. Sacrum is short for os sacrum, "the sacred bone", but I don't know why it was called that. Coccyx is a cuckoo bird, because it looks like a cuckoo's beak. Os innominatum means "nameless bone": they gave up on the name because it doesn't look like anything. (See illustration to right.)
Some of the nondescriptive names are descriptive in Latin, but not in English. The vertebra in English are so called after Latin vertebra, which means the vertebra. But the Latin word is ultimately from the verb vertere, which means to turn. (Like in "avert" ("turn away") and "revert" ("turn back").) The jawbone, or "mandible", is so-called after mandibula, which means "mandible". But the Latin word is ultimately from mandere, which means to chew.
The cranium is Greek, not Latin; kranion (or κρανιον, I suppose) is Greek for "skull". Sternum, the breastbone, is Greek for "chest"; carpus, the wrist, is Greek for "wrist"; tarsus, the ankle, is Greek for "instep". The zygomatic bone of the face is yoke-shaped; ζυγος ("zugos") is Greek for "yoke".
The hyoid bone is the only bone that is not attached to any other bone. (It's located in the throat, and supports the base of the tongue.) It's called the "hyoid" bone because it's shaped like the letter "U". This used to puzzle me, but the way to understand this is to think of it as the "U-oid" bone, which makes sense, and then to remember two things. First, that classical words beginning in "u" often acquire an initial "h" when they come into English, as "humerus". And second, classical Greek "u" always turns into "y" in Latin. You can see this if you look at the shape of the Greek letter capital upsilon, which looks like this: Υ. Greek αβυσσος ("abussos" = "without a bottom") becomes English "abyss"; Greek ανωνυμος ("anonumos") becomes English "anonymous"; Greek υπος ("hupos"; there's supposed to be a diacritical mark on the υ indicating the "h-" sound, but I don't know how to type it) becomes "hypo-" in words like "hypothermia" and "hypodermic". So "U-oid" becomes "hy-oid".
(Other parts of the body named for letters of the alphabet are the sigmoid ("S-shaped") flexure of the colon and the deltoid ("Δ-shaped") muscle in the arm. The optic chiasm is the place in the head where the optic nerves cross; "chiasm" is Greek for a crossing-place, and is so-called after the Greek letter Χ.)
The German word for "auditory ossicles" is Gehörknöchelchen. Gehör is "for hearing". Knöchen is "bones"; Knöchelchen is "little bones". So the German word, like the Latin phrase "auditory ossicles", means "little bones for hearing".