Then there's flexion, where the fetal chin presses against its chest as its head meets resistance from the pelvic floor.

接着是俯屈，颏贴近胸壁，因他头遇到盆肌阻力。

Its location is the infection of submandibular space, which is divided into two compartments by mylohyoid muscle, sublingual compartment (above muscle) , submaxillary and submental compartment (below muscle) .

其颌下腔感染，颌下腔被下颌舌骨肌、舌下腔室（肌上）、上颌下腔室和颏下腔室（肌下）分两个腔室。