The utriculosaccular duct is a part of the

membranous labyrinth The membranous labyrinth is a collection of fluid filled tubes and chambers in the inner ear The inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for soun ...

of the

inner ear The inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for sound detection and balance. In mammals, it consists of the bony labyrinth, a hollow cavity in the ...

which connects the two parts of the vestibule, the utricle and the

saccule The saccule (Latin: sacculus) is a bed of sensory cells in the inner ear that detects linear acceleration and head tilting in the vertical plane, and converts these vibrations into electrical impulses to be interpreted by the brain. When the he ...

. It continues to the

endolymphatic duct From the posterior wall of the saccule a canal, the endolymphatic duct, is given off; this duct is joined by the ductus utriculosaccularis, and then passes along the aquaeductus vestibuli and ends in a blind pouch ( endolymphatic sac) on the pos ...

and ends in the endolymphatic sac.

Importance

This structure plays an important role as a duct that serves as a conduit for endolymph between these structures, maintaining proper fluid dynamics essential for vestibular function. Specifically because the utriculosaccular duct carries the endolymphatic fluid to the endolymphatic sac, where it is drained. This system of the endolymphatic fluid prevents excessive fluid build-up in the inner ear, a condition also known as endolymphatic hydrops, which is associated with Ménière´s disease and others vestibular disorders. Further evidence for this physiological drainage mechanism can be seen in contrast-enhanced

MRI Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and rad ...

, where the post-contrast visibility of endolymphatic sac and duct is inversely correlated to the amount of endolymphatic hydrops, independent of clinical diagnosis.J. Gerb, E. Kierig, V. Kirsch, Sandra Becker‐Bense, Rainer Boegle, Thomas Brandt, Marianne Dieterich: ''Contrast Agent Uptake in Endolymphatic Sac and Duct: Inverse Relation to Endolymphatic Hydrops.'' In: ''The Laryngoscope.'' 2025 .

References

Ear {{anatomy-stub