The Nose Vibrissae Naris Apex (tip) Root Ala Dorsum The external nose Columella = skin that seperates the naris

External Nose

Internal Nose Vestibule Nasal Cavity Proper Skin Very sensitive to pain Hair (Vibrissa) Limen nasi Mucosa - Respiratory and Olfactory Not so sensitive to pain

Nasal Cavity Piriform aperture Nasal septum divides to cavities Tear drop shaped boney opening to the nasal cavity Nasal septum divides to cavities

Bones that contribute to the nose and nasal cavity Frontal Maxilla Ethmoid Inferior Concha Sphenoid Palatine Vomer Lacrimal

Bones of the Nasal walls Roof of cavity is made up of four bones Anterior = frontal &nasal Middle = ethmoidal (cribriform plate) Posterior = Sphenoid Lateral Wall Superior and middle concha are ethmoidal bone Inferior concha is its own bone Small piece of lacrimal bone can be observed Floor Same bones as hard palate frontal

Bones of the Septum cartilage Ethmoid Vomer bone Palatine and Maxilla Septal cartilage extends into vestibule Vomeronasal cartilageif present extends off vomer bone Ethmoid Perpendicular plate extends down from cribriform plate Crista galli is a superior extension Vomer bone Triangle o f bone in inferior posterior nasal septum Palatine and Maxilla form ridges that extend up into nasal cavity Vomer bone slots into these crests

Nasal Concha There are three (sometimes four) turbinates on the lateral wall (called concha) Inferior,Middle, Superior and Supreme (if present) Concha are covered in respiratory epithelium (or olfactory epithelium near cribriform plate. Epithelium serves for heat exchange and to humidify air Bowman's glands secret mucus which coats epithelium Microvilli of epithelium beat down and back to move the mucus towards the nasopharynx. Spaces that allow air flow are meatus and named for the concha above them Note space superior and posterior to superior concha is the sphenoethmoidal recess Common meatus is the space between all concha and the septal wall Inferior meatus

Nasal Concha

Nasal Concha a) Superior concha b) Middle concha c) Inferior concha Superior meatus Middle meatus Common meatus Inferior meatus a 1 b 2 3 c 4

Nerves of the nasal cavity

Nerves Three major nerves Vestibule is the most sensitive CN I, V1, V2 Vestibule is the most sensitive Infraorbital and anterior ethmoidal nerves Nasal mucosa supplied primarily by V2 Anterior by V1 lateral nasal anterior ethmoidal Small part for alveolar

Nerve summery

Blood Supply to Nasal Cavity

Arterial and Venous supply Blood supplied from both internal and external carotid arteries Anterior and posterior ethmoidal come off the ophthalmic artery (from internal carotid) Maxillary branches off the external carotid Facial originates from external carotid Venous plexus of the lateral wall and septum Venous plexuses are important for heat exchange Plexuses can dilate and constrict controlling the aperture of the nasal meatus Venous pathways are roughly the same as the arteries Drainage occurs into the sphenopalatine, facial, or ophthalmic veins Ultimately the pharyngeal or pterygoid plexuses

Epistaxis Anterior nasal septum is the Kiesselbach area Plexus of all five arteries supplying the septum Epistaxis = nose bleed Generally minor nose bleeds are from arterial of venous plexus Spurting of blood likely larger artery (e.g.sphenopalitine)

Blood Summery

Sinuses Sinuses are air filled spaces extensions of the respiratory epithelium They are named for the bones that they are in: Frontal, Ethmoidal, Maxillary, Sphenoid. They serve to expand the surface area of the epithelium to increase heat exchange and aid in humidifying air They produce mucus which must drain into the nasal cavity through various openings to the nasal cavity. Because they are continuous with the nasal cavity infections in the nasal cavity often spread to the sinuses. Because of the small openings of the sinuses often times the they can become obstructed during infections.

Nasal Sinuses Sinuses continue to develop into adulthood Frontal Each grows in size taking over more of the bone Generally stops or decreases in speed around puberty Frontal Rarely symmetrical Innervated by supraorbital nerve (V1) Ethmoidal 20-24 individual cells Innervated by anterior and posterior ethmoidal nerves (V1) Sphenoid Derived from posterior ethmoidal sinus cells Develops after age of 2 Innervated by posterior ethmoidal nerve Maxillary Largest sinus Innervated by alveolar nerves

Sinus MRI Ethmoidal and Maxillary sinuses are obvious

Sinuses Ethmoidal and maxillary sinuses are visible Ethmoidal drainage through multiple ducts. Anteriorly into the ethmoidal infundibulm which leads to the middle meatus Middle directly into the middle meatus (are the air cells that make up the ethmoidal bulla) Posterior drain into the superior meatus Maxillary Sinus drains through the maxillary ostium through the semilunar hiatus and into the middle meatus

Sinus Drainage

Sinus Drainage

Sinus Drainage Note how Frontal and Maxillary Sinuses Drain Ethmoidal infundibulum leads to the middle meatus Semilunar hiatus leads to the middle meatus

Sinus drainage

Rhinitis Nasal mucosa becomes inflamed due to infection or allergic reaction Can be acute or chronic Sinusitis Sinus mucosa becomes inflamed due to infection generally for nasal cavity Nasal Polyps Noncancerous outgrowths of respiratory mucosa that can block airflow Deviated Septum Septal cartilage is deviated from the midline

Development