AN37.1-3 | Cavity of Nose — Gate Quiz

Correct. The nasolacrimal duct opens into the inferior meatus, approximately 1.5 cm posterior to the anterior end of the inferior turbinate. This is clinically important — excessive tearing (epiphora) can result from blockage of this duct, and nasal packing can compress this opening.

The nasolacrimal duct opens into the inferior meatus. The middle meatus receives the maxillary, frontal, and anterior ethmoidal sinuses. The superior meatus receives posterior ethmoidal sinuses. The sphenoethmoidal recess receives the sphenoidal sinus.

Correct. Kiesselbach's plexus receives contributions from 5 arteries: (1) anterior ethmoidal artery (from ophthalmic/ICA), (2) posterior ethmoidal artery (from ophthalmic/ICA), (3) sphenopalatine artery (from maxillary/ECA), (4) greater palatine artery (from maxillary/ECA), and (5) superior labial artery (from facial/ECA). This rich anastomosis makes it the most common site of epistaxis.

Kiesselbach's plexus = 5 arteries: anterior ethmoidal + posterior ethmoidal + sphenopalatine + greater palatine + superior labial (septal branch). This makes Little's area an anastomosis between ICA (ethmoidal) and ECA (sphenopalatine, greater palatine, superior labial) territories.

Correct. The sphenopalatine artery (branch of the maxillary artery) is the main supply to the posterior nasal cavity and inferior turbinate. Posterior epistaxis is typically from this vessel. It is accessed via endoscopic sphenopalatine artery ligation at the sphenopalatine foramen (behind the posterior end of the middle turbinate).

The sphenopalatine artery (from the maxillary artery, ECA) is the largest blood vessel of the nasal cavity and the main source of posterior epistaxis. Anterior epistaxis (90%) is from Kiesselbach's plexus. Posterior epistaxis (10%) is typically from the sphenopalatine artery and is treated by endoscopic ligation or embolisation.

Correct. The maxillary sinus drains via its ostium into the middle meatus, specifically through the hiatus semilunaris (part of the ostiomeatal complex). The frontal sinus and anterior ethmoidal cells also drain here. This common drainage pathway means blockage of the OMC causes multi-sinus sinusitis.

Middle meatus (hiatus semilunaris/ostiomeatal complex) drains the maxillary, frontal, and anterior ethmoidal sinuses. The inferior meatus receives the nasolacrimal duct. The superior meatus receives the posterior ethmoidal sinuses. The sphenoethmoidal recess receives the sphenoidal sinus.

Correct. Rhinocerebral mucormycosis is a rapidly progressive and life-threatening fungal infection caused by Mucor/Rhizopus species in diabetics (especially poorly controlled) and immunocompromised patients. The black eschar (from vascular invasion and tissue necrosis — the fungus invades blood vessel walls) on the nasal mucosa, combined with proptosis and ophthalmoplegia in a diabetic, is pathognomonic. It spreads from the nasal cavity and sinuses via the lamina papyracea to the orbit and via the cribriform plate to the brain.

Black eschar on nasal mucosa + proptosis + ophthalmoplegia in a diabetic = rhinocerebral mucormycosis until proven otherwise. The fungus invades blood vessel walls → ischaemia + necrosis → black eschar. It spreads rapidly from the sinuses to the orbit (via lamina papyracea) and intracranially (via cribriform plate). Treatment: urgent surgical debridement + liposomal amphotericin B.

Correct. The maxillary sinus ostium opens high on the medial wall (near the sinus roof) into the middle meatus. Since the floor of the sinus is below the level of the ostium, secretions accumulate at the floor and cannot drain by gravity in any normal head position. Ciliary transport must actively move secretions uphill to the ostium, making the maxillary sinus particularly susceptible to retention of secretions and chronic infection.

The high position of the maxillary ostium (near the roof of the sinus on the medial wall) is the key anatomical reason for poor drainage. Gravity works against drainage in the upright position — secretions pool at the floor, far below the ostium. This is an anatomical 'design flaw' that makes the maxillary sinus the most commonly involved sinus in sinusitis.

Correct. Infrastructure tumours (below Ohngren's line) are anteroinferior — they involve the alveolus, hard palate, and anterior wall. These produce early symptoms (loose teeth, palatal swelling, cheek lump) allowing earlier detection. Suprastructure tumours (above Ohngren's line) involve the orbit, pterygoid plates, infratemporal fossa, and skull base — they present late, are harder to resect completely, and have a worse prognosis.

Ohngren's line from medial canthus to angle of mandible: below = infrastructure (better prognosis: involves alveolus, palate; earlier symptoms); above = suprastructure (worse prognosis: involves orbit, pterygoids, skull base). The prognosis difference is primarily related to resectability, not histology.

Correct. The lamina papyracea (orbital plate of the ethmoid) is the paper-thin lateral wall of the ethmoid labyrinth, immediately medial to the orbital fat and extraocular muscles. Breach during FESS or due to ethmoidal sinusitis can cause orbital fat herniation, intraorbital haematoma, or injury to the medial rectus muscle.

The lamina papyracea separates the ethmoid labyrinth from the orbit. "Lamina papyracea" literally means "paper layer" — a reminder that it is extremely thin. Ethmoidal sinusitis is the most common cause of orbital cellulitis in children for this reason.

Correct. The floor of the maxillary sinus is formed by the alveolar process of the maxilla. The roots of the upper molars (particularly the first molar and second premolar) are very close to the sinus floor, and in some individuals the root apices project into the sinus with only a thin layer of mucosa between them. Extraction of these teeth can create an oro-antral communication (fistula).

The floor of the maxillary sinus overlies the roots of the upper molar teeth. In many people the root apices of the first molar (and second premolar) project into the sinus floor. Extraction creates an oro-antral communication — patient notices fluid entering nose when drinking, nasal regurgitation.

Correct. The pituitary gland sits in the sella turcica (a bony saddle on the superior surface of the sphenoid body). The sphenoidal sinus is directly below the sella. A surgeon can enter through the nasal cavity → sphenoidal sinus → remove the roof of the sinus (sellar floor) → reach the pituitary gland — a minimally invasive approach that avoids opening the skull.

The pituitary gland is in the sella turcica on the superior surface of the sphenoid body. The sphenoidal sinus pneumatises the body of the sphenoid, placing the sella as the roof of the sinus. Transsphenoidal surgery (endoscopic or microscopic) traverses the nasal cavity, sphenoidal sinus, and the thin sellar floor to reach the pituitary with minimal morbidity.