Describe the anatomy of the nasal cavity and its lateral wall.

The External Nose and Nasal Vestibule

The Lateral Wall

• The lateral wall IS the most important single area IN rhinology, because everything drains onto it and all endoscopic surgery is performed there
• It bears three (sometimes four) turbinates (conchae), each overhanging a meatus into which structures open
• The inferior turbinate is a separate bone; the middle, superior and supreme turbinates are part of the ethmoid
• The inferior meatus receives only the nasolacrimal duct, guarded by the valve of HASNER, 3 cm behind the anterior end of the inferior turbinate. This is the site of antral puncture and of dacryocystorhinostomy
• The middle meatus is the drainage site of the anterior group of sinuses — the maxillary, anterior ethmoid and frontal — and is therefore the key area in sinus disease and in endoscopic sinus surgery
• The superior meatus receives the posterior ethmoid cells
• The sphenoethmoidal recess, above and behind the superior turbinate, receives the sphenoid sinus
• The simple rule that organises all OF this: everything drains into the middle meatus except the nasolacrimal duct (inferior meatus), the posterior ethmoids (superior meatus) and the sphenoid (sphenoethmoidal recess)
• The structures OF the middle meatus.
• The uncinate process — a sickle-shaped bony leaflet, and the first structure removed in endoscopic sinus surgery (uncinectomy)
• The hiatus semilunaris — the two-dimensional cleft between the uncinate process and the ethmoid bulla
• The ethmoid bulla — the largest and most constant anterior ethmoid air cell
• The infundibulum — the three-dimensional channel lateral to the uncinate, into which the maxillary and anterior ethmoid sinuses drain
• The frontal recess — the drainage pathway of the frontal sinus, anterosuperiorly
• The middle turbinate has a three-part attachment that is the key to safe surgery: anteriorly vertical to the cribriform plate, middle oblique (the basal or ground lamella) to the lamina papyracea, and posteriorly horizontal to the lamina papyracea
• The ground lamella is the surgical landmark dividing the anterior from the posterior ethmoid cells
• The vertical attachment reaches the cribriform plate — which is why excessive medial traction on the middle turbinate can fracture the cribriform plate and cause a CSF leak
• Anatomical variants that predispose to sinus disease — concha bullosa (a pneumatised middle turbinate); paradoxical middle turbinate, curving the wrong way; HALLER cells (infraorbital ethmoid cells narrowing the maxillary ostium); ONODI cells (posterior ethmoid cells extending over the sphenoid, intimately related to the optic nerve and a genuine hazard); and AGGER nasi cells, the most anterior ethmoid cells.
• Accessory maxillary ostia occur in a substantial proportion and may cause recirculation of mucus, which is a recognised cause of persistent symptoms after surgery
• The nasal valve is the narrowest part of the airway and contributes about half the total resistance, so small changes there matter greatly
• The vestibule is lined by skin, not mucosa, which is why furuncles and vestibulitis occur there and nowhere else in the nose
• The inferior turbinate is a separate bone; the middle, superior and supreme turbinates belong to the ethmoid
• The nasolacrimal duct is the only thing in the inferior meatus, which is why antral puncture and dacryocystorhinostomy are done there