<prompt> Crus commune is a part of:CochleaMiddle earSemicircular canalVestibule  <response>: c Semicircular canalRef Shambaugh, 6th ed., page 42The posterior and superior semicircular canals fuse together to form a common crus called as crus commune which opens into the utricle. Because of this the three semicircular canals open into utricle by five openings instead of six. 