Basic Sciences for ENT: Anatomy, Physiology, Pathology, Pharmacology
Scope
Basic sciences questions test temporal bone anatomy, laryngeal innervation, sinus drainage, cochlear and vestibular physiology, pathology, and pharmacology relevant to ENT practice. These facts support clinical decisions across all domains.
Core rules
- Facial nerve segments: labyrinthine, tympanic, mastoid, and extratemporal. The geniculate ganglion is the first major landmark after the labyrinthine segment.
- Recurrent laryngeal nerve runs in the tracheoesophageal groove; the external branch of the superior laryngeal nerve supplies the cricothyroid muscle. Injury changes pitch and airway protection.
- Sinus drainage: the ostiomeatal complex drains into the middle meatus. The sphenoid and posterior ethmoid sinuses drain into the superior meatus.
- Cochlear physiology depends on endolymph and perilymph; outer hair cells amplify, inner hair cells transduce. Vestibular hair cells detect head motion.
- Aminoglycosides cause hair cell toxicity, with potential hearing loss and vertigo. Steroids reduce inflammation and edema. Lidocaine with epinephrine prolongs anesthesia and limits bleeding.
- Pathology: HPV is linked to oropharyngeal carcinoma; EBV is linked to nasopharyngeal carcinoma.
Worked example
A patient receiving gentamicin develops disequilibrium and high-frequency hearing loss. The mechanism is aminoglycoside toxicity to vestibular and cochlear hair cells. Stop the drug, obtain audiometry and vestibular assessment, and monitor renal function.
Traps
Confusing recurrent laryngeal and superior laryngeal nerve function; assuming all antibiotics are otologically safe; missing the ostiomeatal complex; and ignoring HPV and EBV associations in head and neck cancer.