▁the ▁mouth ▁is ▁the ▁first ▁portion ▁of ▁the ▁aliment ary ▁canal ▁that ▁receives ▁food ▁and ▁produces ▁sal iva . ▁The ▁or al ▁m uc osa ▁is ▁the ▁m uc ous ▁memb rane ▁ep ith el ium ▁l ining ▁the ▁inside ▁of ▁the ▁mouth . ▁ ▁In ▁addition ▁to ▁its ▁primary ▁role ▁as ▁the ▁beginning ▁of ▁the ▁dig est ive ▁system , ▁in ▁humans ▁the ▁mouth ▁also ▁plays ▁a ▁significant ▁role ▁in ▁communication . ▁While ▁primary ▁aspects ▁of ▁the ▁voice ▁are ▁produced ▁in ▁the ▁thro at , ▁the ▁tongue , ▁lips , ▁and ▁j aw ▁are ▁also ▁needed ▁to ▁produce ▁the ▁range ▁of ▁sounds ▁included ▁in ▁human ▁language . ▁ ▁The ▁mouth ▁consists ▁of ▁two ▁regions , ▁the ▁vest ib ule ▁and ▁the ▁or al ▁cav ity ▁proper . ▁The ▁mouth , ▁normally ▁mo ist , ▁is ▁l ined ▁with ▁a ▁m uc ous ▁memb rane , ▁and ▁contains ▁the ▁teeth . ▁ ▁The ▁lips ▁mark ▁the ▁transition ▁from ▁m uc ous ▁memb rane ▁to ▁skin , ▁which ▁covers ▁most ▁of ▁the ▁body . ▁ ▁Str ucture ▁ ▁Or al ▁cav ity ▁▁▁ ▁The ▁mouth ▁consists ▁of ▁ 2 ▁regions : ▁the ▁vest ib ule ▁and ▁the ▁or al ▁cav ity ▁proper . ▁The ▁vest ib ule ▁is ▁the ▁area ▁between ▁the ▁teeth , ▁lips ▁and ▁che eks . ▁The ▁or al ▁cav ity ▁is ▁bounded ▁at ▁the ▁sides ▁and ▁in ▁front ▁by ▁the ▁al ve olar ▁process ▁( cont aining ▁the ▁teeth ) ▁and ▁at ▁the ▁back ▁by ▁the ▁is th mus ▁of