Endolymph produced by the stria vascularis must be resorbed to maintain labyrinthine fluid balance. Which structure performs this absorptive function?

• A Vestibular aqueduct epithelium alone, independent of any terminal sac
• B Spiral ganglion
• C Basilar membrane
• D Endolymphatic sac ✓

Explanation

Endolymph flows along the endolymphatic duct through the vestibular aqueduct to the endolymphatic sac, which lies between the two layers of dura mater on the posterior surface of the petrous temporal bone. Its epithelium absorbs endolymph and its macrophages clear debris. Distension of this system is implicated in Meniere disease, where surgical decompression of the sac was historically attempted. The spiral ganglion houses auditory neurons and the basilar membrane is mechanical, neither participates in fluid resorption.

Reference: Gray's Anatomy, 42nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.