Nasal And Paranasal Physiology And Anatomy

Paranasal Sinus Anatomy

Lateral Nasal Wall (Fig. 1-1)

• Uncinate Process: sickle-shaped thin bone part of the ethmoid bone, covered by mucoperiosteum, medial to the ethmoid infundibulum and lateral to the middle turbinate (derived from the second ethmoidal turbinal)

• Ethmoid Infundibulum: pyramidal space that houses opening to the maxillary and anterior ethmoid sinuses; superior attachment determines spatial relationship of frontal sinus drainage (80% attach to the lamina papyracea resulting in frontal sinus drainage medial to the uncinate, 20% attach to the skull base or middle turbinate resulting in frontal sinus drainage lateral to the uncinate and into the infundibulum)

• Semilunar Hiatus: gap that empties the ethmoid infundibulum, located between the uncinate process and the ethmoid bulla

• Sphenopalatine Foramen: posterior to inferior attachment of the middle turbinate, contains sphenopalatine artery, sensory nerve fibers, and secretomotor fibers (parasympathetic fibers from vidian nerve to pterygopalatine ganglion)

• Concha Bullosa: an aerated middle turbinate, may result in nasal obstruction

• Osteomeatal Complex: region referring to the anterior ethmoids containing the ostia of the maxillary, frontal, and ethmoid sinuses, lateral to the middle turbinate

Frontal Sinus

• Embryology: does not appear until 5—6 years old

• Volume at Adult: 4-7 ml by 12-20 years old (5-10% underdeveloped)

• Drainage: frontal recess in anterior middle meatus either medial or lateral to the uncinate (posterior and medial to agar nasi cells), may also be lateral to agar nasi cells

• Vasculature: supraorbital and supratrochlear arteries, ophthalmic (cavernous sinus) and supraorbital (anterior facial) veins

• Innervation: supraorbital and supratrochlear nerves (V1)

• Plain Film: lateral and Caldwell view

• Foramina of Breschet: small venules that drain the sinus mucosa into the dural veins

Frontal sinus

Ant. ethmoid artery

Agger nasi

Uncinate process

Cut edge of inferior turbinate

Ostium of nasosolacrimal duct

Post. ethmoid artery

Frontal sinus

Ant. ethmoid artery

Agger nasi

Uncinate process

Post. ethmoid artery

Cut edge of inferior turbinate

Ostium of nasosolacrimal duct

Maxillary Crest Sphenopalatine Artery

Sphenopalatine foramen

Sphenoid sinus

Sphenopalatine artery

Ethmoidal bulla

Incisive Semilunaris Greater Greater canal hiatus palatine artery palatine foramen

FIGURE 1—1. Anatomy of the lateral nasal wall including vascular supply.

Orifice of sphenoidal sinus

Sella turcica

Sphenopalatine foramen

Sphenoid sinus

Sphenopalatine artery

Ethmoidal bulla

Incisive Semilunaris Greater Greater canal hiatus palatine artery palatine foramen

FIGURE 1—1. Anatomy of the lateral nasal wall including vascular supply.

Maxillary Sinus

• Embryology: first to develop in utero, biphasic growth at 3 and 7—18 years old

• Volume at Adult: typically 15 ml (largest paranasal sinus)

• Drainage: ethmoid infundibulum (middle meatus, 10—30% have accessory ostium)

• Vasculature: maxillary and facial artery, maxillary vein

• Innervation: infraorbital nerve (V2)

• Adjacent Structures: lateral nasal wall, alveolar process of maxilla (contains second bicuspid and first and second molars), orbital floor, posterior maxillary wall (contains pterygopalatine fossa housing the maxillary artery, pterygopalatine ganglion, and branches of the trigeminal nerve)

Ethmoid Sinus

• Embryology: 3—4 cells at birth (most developed paranasal sinus at birth), formed from 5 ethmoid turbinals (1. agar nasi, 2. uncinate, 3. ethmoid bulla, 4. ground lamella, 5. posterior wall of the most posterior ethmoid cell)

• Volume at Adult: 10—15 aerated cells, total volume of 2—3 ml (adult size at 12—15 years old)

• Drainage: anterior cells drain into the ethmoid infundibulum, posterior cells drain into the spheno-ethmoid recess (superior meatus)

• Vasculature: anterior and posterior ethmoid arteries (from ophthalmic artery), maxillary and ethmoid veins (cavernous sinus)

• Innervation: anterior and posterior ethmoidal nerves (from nasociliary nerve, V1)

• Plain Film: lateral and Caldwell view

• Adjacent Structures: skull base, anterior ethmoid artery (roof of anterior ethmoid cells), nasal cavity, orbit

• Agger Nasi Cells: most anterior of anterior ethmoid cells

• Ground (Basal) Lamella: posterior bony insertion of the middle turbinate which separates anterior and posterior ethmoid cells; posterior extension of the middle turbinate

• Onodi Cells: ethmoid cells that pneumatize lateral or posterior to anterior wall of the sphenoid, commonly mistaken as a sphenoid cell, optic nerve may indent into the lateral wall

• Haller Cells: ethmoid cells that extend into maxillary sinus above the ostium, pneumatize the medial and inferior orbital walls

• Lamina Papyracea: lateral thin bony wall of the ethmoid sinus, separates orbit from ethmoid cells as a part of the medial orbital wall

• Fovea Ethmoidalis: roof of ethmoid sinus

Sphenoid Sinus

• Embryology: evagination of nasal mucosa into sphenoid bone

• Volume at Adult: 0.5-8 ml (adult size at 12-18 years old)

• Drainage: sphenoethmoid recess in the superior meatus

• Vasculature: sphenopalatine artery (from maxillary artery), maxillary vein (pterygoid plexus)

• Innervation: sphenopalatine nerve (parasympathetic fibers and V2)

• Plain Film: lateral and submentovertex (basal)

• Adjacent Structures: pons, pituitary (sella turcica), carotid artery (lateral wall), optic nerve (lateral wall), cavernous sinus (laterally), maxillary and abducens nerves, clivus

Anatomical Relationships of the Sphenoid Ostium

• adjacent to posterior border of nasal septum

• 6-8 cm posterior to the anterior nasal spine

• typically 1.5 cm above the choanal floor

• 1/3 up from the choana to the base of skull

Nasal Anatomy

Nasal Cartilage

• Upper Lateral Cartilage

• Lower Lateral (Alar) Cartilage: paired cartilage, composed of lateral and medial crura

• Sesamoid Cartilage

• Lesser Alar Cartilage

Septal Anatomy (Fig. 1-2)

• Quadrangular Cartilage: septal cartilage

• Perpendicular Plate of the Ethmoid: projects from cribiform plate to septal cartilage

• Vomer: posterior and inferior to perpendicular plate

• Maxillary Crest (Palatine Bone): trough of bone that supports the septal cartilage

• Anterior Nasal Spine: bony projection anterior to pyriform aperture

Frontal sinus

Septal branch of anterior ethmoid artery

Nasal bone

Kiesselbach's plexus

Quadrangular cartilage

Anterior nasal spine

Septal branch of superior labial artery Greater palatine artery

Perpendicular plate of ethmoid bone

Frontal sinus

Septal branch of anterior ethmoid artery

Nasal bone

Perpendicular plate of ethmoid bone

Kiesselbach's plexus

Anterior Ethmoidal Nerve

Post. ethmoid artery

Sella turcica

Sphenoid sinus

Anterior nasal spine

Nasal crest of the palatine bone

Post. ethmoid artery

Sella turcica

Sphenoid sinus

Medial plate of the pterygoid process (sphenoid bone)

Perpendicular plate of the palatine bone

Pterygoid hamulus

Nasal crest of the palatine bone

FIGURE 1-2. Anatomy of the septum including blood supply.

Sensory Innervation External Innervation

• Supratrochlear and Infratrochlear Nerves (CN Vi): nasal dorsum

• External Nasal Branch of Anterior Ethmoid (CN V1): nasal tip

• Infraorbital Nerve (CN V2): malar, lateral nose, and subnasal regions

Internal Innervation

• Internal Nasal Branch of Anterior Ethmoid (CN V1): anterosuperior nasal cavity

• Posterior Ethmoid Nerve (CN Vi): posterior nasal cavity

• Sphenopalatine Nerve (CN V2): posterior and inferior nasal cavity

• Superior Alveolar Nerves (CN V2)

Vascular Anatomy (Fig. 1-1 and 1-2) External Carotid Artery Branches Internal Maxillary Artery

• descending palatine artery ^ greater palatine and lesser palatine arteries

• sphenopalatine artery ^ sphenopalatine foramen (posterior to the middle turbinate) ^ medial (nasoseptal) and lateral nasal artery (middle and inferior turbinates)

Facial Artery

• superior labial artery ^ nasal septum and alar branches

• lateral nasal artery

• angular artery

Internal Carotid Artery Branches (branches of ophthalmic artery)

• anterior ethmoid artery (larger than the posterior ethmoid artery) ^ lateral nasal wall and septum

• posterior ethmoidal artery ^ superior concha and septum

• dorsal nasal artery ^ external nose

Venous System

• greater palatine vein drains into posterior facial vein (external jugular vein) and cavernous sinus

• septal vein drains into anterior facial vein (internal jugular vein)

• sphenopalatine vein drains into cavernous sinus and maxillary vein (internal jugular vein)

• anterior and posterior ethmoidal veins drain into ophthalmic veins (cavernous sinus)

• angular vein drains into anterior facial vein (internal jugular vein)

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