Anatomy of Nose & Paranasal Sinuses Dr. Vishal Sharma

Development of nose

Face develops from 5 projections: frontonasal process (ectoderm over forebrain) + 2 maxillary processes + 2 mandibular processes (1st arch) An ectodermal olfactory placode divides fronto-nasal process into medial nasal & lateral nasal process, which give rise to external nasal skeleton Olfactory placode deepens into olfactory pit & later olfactory sac which forms nasal cavities Nasal septum develops from mesodermal tecto-septal expansion from Rathke’s pouch

External Framework

External Framework Nasal Bone Frontal Process of Maxilla Upper Lateral Nasal Cartilage Lower Lateral Nasal (Alar) Cartilage Septal Cartilage Lesser Alar (Sesamoid) Cartilages

Internal Nose Openings: Anterior nares & posterior nares (Choanae). Vestibule of nose: lined by skin Nasal cavity proper:  Lateral Wall  Medial Wall (Septum)  Roof  Floor

Nasal Septum

Nasal Septum

Nasal Septum 1. Septal cartilage 7. Medial alar crus 2. Ethmoid plate 8. Upper lateral cartilage 3. Vomer 9. Nasal bone crest 4. Palatine crest 10. Frontal spine 5. Maxillary crest 11. Sphenoid rostrum 6. Vomeronasal 12. Membranous septum cartilage

Lateral Nasal Wall  3 - 4 bony conchae covered with mucosa to form turbinates. Space below & lateral to turbinate is called meatus.  Middle meatus contains a round bulla ethmoidalis separated from uncinate process by hiatus semilunaris that leads to a funnel shaped ethmoidal infundibulum.

Meatal Drainage 1. Inferior meatus: Nasolacrimal duct ( guarded at its end by a mucosal valve called HASNER’s valve ) 2. Middle meatus: a. Frontal b. Anterior ethmoid c. Maxillary (natural + accessory ostia) 3. Superior meatus: Posterior ethmoid 4. Spheno-ethmoidal recess: Sphenoid

Ostio-meatal Complex

Ostio-meatal Complex Complex micro-architectural pathway in ethmoid labyrinth that drains anterior group of paranasal sinuses. Consists of: frontal recess + ethmoid infundibulum + hiatus semilunaris + uncinate process + bulla ethmoidalis + middle meatus. O.M.C. pathology leads to infection of all anterior paranasal sinuses (Naumann).

Variants in O.M.C. Concha bullosa (pneumatized M.T.) Paradoxically curved middle turbinate Medially turned uncinate process Large bulla ethmoidalis Haller’s cell in orbital floor Agger nasi cell anterior to M.T. Onodi Cell with dehiscent Optic Nerve Mucosal pathology

Concha bullosa

Concha bullosa

Paradoxically curved M.T.

Paradoxically curved M.T.

Medialized Uncinate Process

Large bulla ethmoidalis

Haller cell

Agger nasi cell

Onodi cell with dehiscent optic nv

Mucosal disease

Blood Supply Sphenopalatine artery (main artery) Greater palatine artery Superior labial artery Anterior Ethmoidal artery Posterior Ethmoidal artery 1, 2, 3 & 4 form Kiesselbach’s plexus over Little’s area on anterior septum

Venous drainage Ethmoidal veins:  ophthalmic veins  cavernous sinus Sphenopalatine vein:  pterygoid plexus  maxillary vein  Woodruff’s venous plexus: present on lateral wall near posterior end of middle turbinate Retro-columellar vein: behind columella

Sensory Nerve Supply Long & short Nasopalatine nerves Greater palatine nerve Infra-orbital nerve branches Anterior ethmoidal nerve Olfactory nerve

Autonomic Nerve Supply Deep petrosal nerve (sympathetic) + greater superficial petrosal nerve (para-sympathetic)  vidian nerve  pterygo-palatine ganglion  nasal glands Sympathetic stimulation  vasoconstriction + ed nasal secretions Para-sympathetic stimulation  vasodilatation + ed nasal secretions

Lining Epithelium Skin: over nasal vestibule Olfactory epithelium: upper 1/3rd of nasal cavity above superior turbinate Respiratory epithelium (pseudo-stratified ciliated columnar): rest of nasal cavity + paranasal sinus

Lining Epithelium

Lymphatic Drainage 1. External nose & anterior nasal cavity  submandibular lymph nodes 2. Remaining nasal cavity  upper deep cervical lymph nodes 3. Nasal roof (dangerous area of nose)  subarachnoid space along olfactory nv 4. P.N.S.  retropharyngeal & J.D. node

Paranasal Sinuses Anterior group:  frontal  anterior ethmoidal  maxillary Posterior group:  posterior ethmoidal  sphenoid

First X-ray appearance Development of P.N.S. Appear first First X-ray appearance Reach adult size by Maxillary At birth 4 mth 15 yr Ethmoidal 1yr 12 yr Sphenoid 2 yr 4 yr 18 yr Frontal 6 yr

Sphenoid Sinus Relations

Muco-ciliary blanket Goblet cells in nasal mucosa secrete a mucous blanket; moved backwards like a conveyer belt into nasopharynx. Consists of:  Superficial mucous or gel layer  Deep serous or sol layer

Muco-ciliary blanket

Muco-ciliary blanket

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