saccule
noun
sac·cule ˈsa-(ˌ)kyül 
: a little sac
specifically : the smaller chamber of the membranous labyrinth of the ear
Example Sentences
Recent Examples on the Web In those individuals, Balaban says, further tests implicated damage to the ear's otolith organs, the utricle and the saccule, key to sensing gravity. 
Richard Stone, Science | AAAS, 20 June 2018
Richard Stone, Science | AAAS, 20 June 2018 Word History
Etymology
New Latin sacculus, from Latin, diminutive of saccus bag — more at sack
First Known Use
circa 1839, in the meaning defined above
Medical Definition
saccule
noun
sac·cule ˈsak-(ˌ)yü(ə)l
: a little sac
specifically : the smaller chamber of the membranous labyrinth of the ear that contains the macula sacculi