ABTU KUB LURDER KHO NTXHAIS

Voj voog: Ib qho ntawm cov kev tshwm sim feem ntau, nrog txoj kab uas hla feem ntau yog li 5 hli txog 50 hli. Qhov puab ntawm cov roj hmab taw tuaj yeem faib cov nyiaj siab thiab haum rau ntau cov khoom siv nrog cov khoom siv hluav taws xob kom ruaj khov thiab cov rooj zaum hauv qab thiab cov khoom siv hauv tsev.

Xwm fab xwm meem: Sab ntev feem pua ​​feem pua ​​feem pua ​​ntawm 10 hli mus rau 100 hli. Vim tias nws cov ces kaum, thaum siv nyob rau hauv qab ntawm qee rooj tog uas yuav tsum muaj rau kev sib koom tes,

Xws li cov rooj kas fes thiab cov tub ceev, nws tuaj yeem ua kom tiav cov duab xwm txheej ntawm cov rooj tog zaum ntawm cov rooj tog zaum thiab txhim kho cov kev ua kom zoo nkauj tag nrho.
Semicircular:Feem ntau siv nyob rau hauv qee cov khoom lag luam nrog cov qauv tsim tshwj xeeb uas yuav tsum muaj rau cov tsos, nrog lub vojvoog feem ntau yog kwv yees li 5 hli mus rau 30 hli. Nws cov qauv tshwj xeeb tuaj yeem ntxiv cov txiaj ntsig zoo nkauj rau cov khoom yam tsis muaj kev cuam tshuam nws txoj haujlwm. Piv txwv li, nws yog siv rau hauv qab ntawm qee yam khoom vaj tswv tsev.