Perilymph within the scala tympani communicates directly with cerebrospinal fluid through which channel?
- A The vestibular aqueduct, extending from the utricle to the posterior cranial fossa
- B The cochlear aqueduct, extending from the basal turn to the subarachnoid space ✓
- C The petrotympanic fissure, connecting the middle ear to the infratemporal fossa
- D The hiatus of the facial canal, connecting the scala tympani to the geniculate ganglion
Correct answer: B. The cochlear aqueduct, extending from the basal turn to the subarachnoid space
Explanation
The cochlear aqueduct runs from the scala tympani near the round window to the subarachnoid space of the posterior cranial fossa, allowing free communication between perilymph and CSF. Clinically it explains perilymph gusher during stapes surgery and CSF leakage into the middle ear. The vestibular aqueduct carries the endolymphatic duct and sac and concerns endolymph, not perilymph, which eliminates the strongest distractor.
Reference: Cummings Otolaryngology Head and Neck Surgery, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.