Otolaryngologic Anatomy Flashcards

Where does the nasolacrimal duct open into the nasal cavity?

Answer: Inferior meatus

The nasolacrimal duct opens into the inferior meatus under the inferior turbinate, and Hasner's valve guards the opening.

The sphenoid sinus ostium drains into which area?

Answer: Sphenoethmoidal recess

The sphenoid sinus drains into the sphenoethmoidal recess, which lies medial to the superior turbinate and above it.

Which artery is the main source of posterior epistaxis?

Answer: Sphenopalatine artery

Posterior epistaxis usually comes from branches of the sphenopalatine artery, which is why endoscopic sphenopalatine artery ligation is a standard treatment.

A posterior ethmoid cell that pneumatizes lateral to the sphenoid sinus and above it puts which structure at risk during surgery?

Answer: Optic nerve

An Onodi (sphenoethmoidal) cell can surround the optic nerve, so the nerve is at risk during posterior ethmoidectomy.

An ethmoid cell that pneumatizes along the medial orbital floor and can narrow the ethmoid infundibulum is called:

Answer: Haller cell

Haller (infraorbital ethmoid) cells lie under the orbit and can block maxillary sinus drainage.

Which structure divides the anterior ethmoid cells from the posterior ethmoid cells?

Answer: Basal (ground) lamella of the middle turbinate

The basal lamella of the middle turbinate attaches laterally to the lamina papyracea and separates the anterior ethmoid cells from the posterior ones.

The Keros classification on preoperative CT measures what?

Answer: Height of the lateral lamella of the cribriform plate (olfactory fossa depth)

The Keros classification grades olfactory fossa depth (type I 1-3 mm, type II 4-7 mm, type III 8-16 mm); deeper fossae carry a higher risk of skull base injury.