Sinonasal Anatomy NOTHING TO DISCLOSE

Hillary R. Kelly, M.D. Massachusetts Eye and Ear Infirmary Massachusetts Eye and Ear Infirmary Massachusetts General Hospital Massachusetts General Hospital Harvard Medical School Harvard Medical School

Organization Anterior skull base Anatomy: • Anterior skull base • Crista galli • Olfactory groove • • Olfactory recess • Drainage pathways **Variants** • Cribriform plate • Sphenoethmoidal region – Medial lamella • and recess – Vertical lamella • Basal lamellae • Fovea ethmoidalis – Roof of the • • Ostiomeatal unit

Anterior skull base Anterior skull base Variants: Keros • Crista galli Classification • Olfactory groove • Olfactory recess • Cribriform plate – Medial lamella – Vertical lamella • Fovea ethmoidalis – Roof of the ethmoid sinus 1-3 mm 4-7 mm 8-16 mm Fovea ethmoidalis ≠ Cribriform plate!! Gauba V, Saleh GM, Dua G, et al. Radiological classification of anterior skull base anatomy prior to performing medial orbital wall decompression. Orbit. 2006;25 (2): 93-6. Anterior skull base Ethmoid roofs: symmetric? Variants: Keros Classification

1-3 mm 4-7 mm 8-16 mm

Keros P. On the practical value of differences in the level of the lamina cribrosa of the ethmoid. Z Laryngol Rhinol Otol. 1962;41:809-13.

Ethmoid roofs: intact? Lamina papyracea: intact?

Nasal cavity Nasal cavity Choanae Posterior boundary of nasal Pyriform aperture cavity Opening into nasopharynx

Anterior opening to nasal cavity

** width of < 11 mm in term infant is considered diagnostic of pyriform aperture stenosis** ** width of choanal airspace > 0.34 mm diagnostic of stenosis in newborn** ** vomer abnormal if > 0.23 mm**

Belden CJ et al: CT features of congenital nasal piriform aperture stenosis: initial experience. Radiology. 213(2):495-501, 1999 Slovis TL et al: Choanal atresia: precise CT evaluation. Radiology. 155(2):345-8, 1985 Nasal cavity Nasal cavity Nasal septum

Sedaghat AR, Kieff DA, Bergmark RW, Cunnane ME, Bus-aba NY. Radiographic evaluation of nasal septal deviationfrom computed tomography correlates poorly with physical exam findings. Int Forum Allergy Rhinol. 2015;5:258–262.

Nasal cavity Drainage pathways

• Superior meatus • Superior, middle and – Sphenoids via sphenoethmoidal recess inferior turbinates – Posterior ethmoids directly • Middle meatus • Superior, middle and inferior meati lateral and – Frontals via frontoethmoidal recesses inferior to the turbinates – Maxillary via infundibula – Ethmoids directly

Superior meatus: sphenoid and Superior meatus: sphenoid and posterior ethmoids posterior ethmoids Sphenoethmoidal variant Sphenoethmoidal variant

Sphenoid pneumatization Middle meatus: frontal recess

Delano M, Fun F, Zinreich SJ: Optic nerve relationship to the posterior : a CT anatomic study. AJNR Am J Neuroradiol. 1996;17:669-675

Middle meatus: frontal recess Middle meatus: frontal recess Frontal variant Frontoethmoidal variant

Supraorbital air cell

Middle meatus: anterior ethmoids Middle meatus: maxillary sinus

Maxillary sinus variant Inferior meatus: nasolacrimal duct

Infraorbital ethmoid air cell Middle turbinate Ostiomeatal Complex

2 attachments: ! Vertical ! Lateral (basal lamella)

Variants: Ostiomeatal Complex • Concha bullosa • Paradoxical turbinate • Septal spur • Infundibulum • Uncinate process • Middle meatus

Thank you!