The extremities of the ductus cochlearis are closed; the upper is termed the lagena and is attached to the cupula

Cochlear cupula

The cochlear cupula is a structure in the cochlea. It is the apex of the cochlea.The bony canal of the cochlea takes two and three-quarter turns around the modiolus. The modiolus is about 30 mm. in length, and diminishes gradually in diameter from the base to the summit, where it terminates in...

 at the upper part of the helicotrema

Helicotrema

The helicotrema is the part of the cochlear labyrinth where the scala tympani and the scala vestibuli meet. It is the main component of the cochlear apex. The hair cells in this area best detect low frequency sounds.-External links:* at Allegheny University of the Health Sciences* at IUPUI...

; the lower is lodged in the recessus cochlearis of the vestibule

Vestibule of the ear

-Definition:The vestibule is the central part of the osseous labyrinth, and is situated medial to the tympanic cavity, behind the cochlea, and in front of the semicircular canals.The etymology comes from the Latin vestibulum, literally an entrance hall....

.

In fish and amphibians

The lagena is part of the vestibular system

Vestibular system

The vestibular system, which contributes to balance in most mammals and to the sense of spatial orientation, is the sensory system that provides the leading contribution about movement and sense of balance. Together with the cochlea, a part of the auditory system, it constitutes the labyrinth of...

 in fish and amphibians. It contains the otolith

Otolith

An otolith, , also called statoconium or otoconium is a structure in the saccule or utricle of the inner ear, specifically in the vestibular labyrinth of vertebrates. The saccule and utricle, in turn, together make the otolith organs. They are sensitive to gravity and linear acceleration...

s asterisci. In fish, the lagena is implied in hearing and the registration of vertical linear acceleration, in amphibians in the latter only.