In the inner ear, the endolymphatic sac is located:
- A Within the petrous bone fully enclosed in bone
- B Partly in the vestibular aqueduct and partly between the layers of the posterior fossa dura ✓
- C Inside the cochlear aqueduct at the basal turn
- D Embedded in the modiolus adjacent to the spiral ganglion
Correct answer: B. Partly in the vestibular aqueduct and partly between the layers of the posterior fossa dura
Explanation
The endolymphatic duct runs through the vestibular aqueduct and terminates in the endolymphatic sac, which lies partly within the vestibular aqueduct and partly between the two layers of the dura of the posterior cranial fossa (extradural position on the posterior surface of the petrous bone). This anatomy is surgically important in endolymphatic sac decompression for Meniere's disease. The cochlear aqueduct carries perilymph, not endolymph.
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.