2006-09-02 02:05:39 · 18 answers · asked by Anonymous in Science & Mathematics ➔ Biology
because the top jaw is connected to your skull, the bottom jaw has kind of like hinges. Same reason why a cabinet door will swing open and the cabinet not move.
2006-09-02 02:08:59 · answer #1 · answered by mixemup 6 · 1⤊ 0⤋
It kind of does:
your bottom jaw moves down, but only in relation to the rest of your skull. If your bottom jaw and top jaw moved in the same direction, you'd just look down, and your mouth would stay closed.
It is possible to open your mouth keeping your jaw and neck in the same place relative to eachother, tilting your head back slightly, like a PEZ dispenser.
2006-09-04 01:17:15 · answer #2 · answered by ewanspewan 4 · 0⤊ 0⤋
Because the top jaw is fixed, attached to the skull and incapable of moving independently.
2006-09-05 23:50:23 · answer #3 · answered by a_phantoms_rose 7 · 0⤊ 0⤋
Well if your top jaw moved your whole head would have to move to, it's easier just to move the bottom jaw.
2006-09-02 02:07:58 · answer #4 · answered by Anonymous · 0⤊ 0⤋
As far as I know you only have one jaw, and thats the thing that moves up and down when you open and close your mouth, the part that it is hinged to is your skull. If your jaw didn`t move you would be nodding. :o)
2006-09-02 02:14:01 · answer #5 · answered by Spanner 6 · 0⤊ 0⤋
If your top jaw moved then your brain would slide down the back of your throat!
2006-09-04 06:29:34 · answer #6 · answered by [deleted] 2 · 0⤊ 0⤋
The upper jaw and skull are kept steady so that whilst eating the approach of any other predators can be observed.
2006-09-02 07:16:53 · answer #7 · answered by InnerGuard 2 · 0⤊ 0⤋
Because your bottom jaw is hinged to the top one.
2006-09-02 02:21:57 · answer #8 · answered by xxsnsxx@verizon.net 2 · 0⤊ 0⤋
it is one of the impotant traits developed during the evolution of man and also the earth, even in most of the animals, the lower jaw is movable. the answer surprisingly lies in physics. on account of gravity, all the matter tends to be attracted towards the earth...vertically down, to be precise. irrespective of the gravity, we have evolved with most of our moable parts grown away from gravity (for eg. legs are primary parts oriented away from the direction of gravity). similarly, for food to be properly disintegrated, it was imperative for that jaw to be movable which was oriented away from the gravity, as a general rule. the lower jaw, thus designated itself as more compatible for the purpose.
2006-09-02 02:19:01 · answer #9 · answered by Anonymous · 0⤊ 0⤋
cuz of the whole "top jaw connected to the skull" thingy
2006-09-02 02:12:07 · answer #10 · answered by the greg 5 · 0⤊ 0⤋