The endolymphatic sac is located in which anatomical compartment and is responsible for endolymph resorption. Dysfunction of this structure is implicated in the pathogenesis of which condition?

• A Posterior cranial fossa dural folds; Meniere's disease ✓
• B Petrous apex air cells; otosclerosis
• C Internal auditory canal; acoustic neuroma
• D Mastoid air cell system; BPPV

Explanation

The endolymphatic sac lies in a fold of dura in the posterior cranial fossa between the layers of the dura mater on the posterior surface of the petrous temporal bone. It is the primary site of endolymph resorption and immune function. Obstruction or dysfunction of the endolymphatic duct-sac system leads to endolymphatic hydrops — distension of the membranous labyrinth — which is the pathophysiological basis of Meniere's disease. Surgical procedures such as endolymphatic sac decompression or shunting target this structure. Otosclerosis involves the bony labyrinth capsule; BPPV involves otolith displacement into the semicircular canals.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.