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Anatomy of the Nose - Complete Reference

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Overview

1. External nose - the visible projecting structure on the face
2. Internal nose (nasal cavity) - a passage approximately 6-7 cm long running above the roof of the mouth

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1. EMBRYOLOGY

• Neural crest cells proliferate to form nasal placodes
• Medial and lateral nasal processes develop adjacent to the placodes
• Medial nasal processes fuse with the frontal prominence to form: nasal bones, frontal bones, cartilaginous nose, ethmoid bones, central incisors, and hard palate
• Nasobuccal membrane ruptures by week 10, opening communication between nose and nasopharynx
• Nasal septum develops as a downgrowth from the merged medial nasal processes; fuses with the palatine processes anteriorly at week 9, completed posteriorly by week 12

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2. EXTERNAL NOSE ANATOMY

2a. Surface Landmarks

2b. Nasal Skeleton

• Nasal bones (paired) - form the bony bridge; articulate superiorly with the nasal process of the frontal bone, laterally with the frontal process of the maxilla
• Pyriform aperture - the bony opening into the nasal cavity, bounded superiorly by the caudal margin of nasal bones, inferiorly by the alveolar process of maxilla, laterally by the frontal process of maxilla, medially by the nasal septum

• Upper Lateral Cartilage (ULC)
  • Attached superiorly to nasal bones
  • Articulates inferiorly with the cephalic margin of the lower lateral cartilage (LLC), often forming an interlocking scroll
  • Thickens medially, becoming continuous with the quadrangular (septal) cartilage, forming the cartilaginous dorsum
• Lower Lateral Cartilage (LLC)
  • Provides shape of the nasal tip
  • Composed of medial and lateral crura
• Sesamoid cartilages - small cartilages lateral to the lateral crus

2c. Subcutaneous Layers

2d. Nasal Musculature

• Procerus, levator labii superioris alaeque nasi, anomalous nasi

• Alar nasalis, depressor septi, compressor narium minor

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3. NASAL SEPTUM

• Quadrangular cartilage - the main component, forms the anterior portion

• Perpendicular plate of the ethmoid (posterosuperior)
• Vomer (posteroinferior)
• Crest of the maxillary bone
• Crest of the palatine bone
• Minor contributions: crest of sphenoid bone, nasal spine of frontal bone

• Membranous (mobile) septum - cartilage-deficient membrane adjoining the columella to the caudal septum; site of hemitransfixion/transfixion incision
• Keystone area - convergence of the caudal margin of nasal bone, perpendicular plate of ethmoid, cephalic margin of ULC, and cartilaginous septum; failure to preserve this during surgery causes nasal collapse
• Vomeronasal organ (Jacobsen's organ) - auxiliary olfactory organ (largely regresses in utero); identified as a groove in the anterior-inferior nasal septum

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4. NASAL CAVITY

4a. Boundaries

4b. Divisions of the Nasal Cavity

1. Vestibule - entrance lined by hair-bearing skin, sebaceous and sweat glands
   • Boundaries: medially = nasal septum; superior/lateral = LLC; inferior = alveolar process of maxilla; posterior = limen nasi (caudal margin of ULC)
   • The limen nasi marks the transition from skin to pseudostratified ciliated columnar epithelium (respiratory mucosa)
2. Olfactory region - superior, adjacent to the cribriform plate; lined with specialized olfactory epithelium
3. Respiratory region - the majority of the cavity; lined with pseudostratified ciliated columnar epithelium (respiratory mucosa) with goblet cells

4c. Lateral Wall and Turbinates

1. Frontal process of maxilla
2. Lacrimal bone
3. Medial maxillary wall inferiorly / lamina papyracea (LP) superiorly
4. Perpendicular plate of the palatine bone
5. Medial pterygoid plate of the sphenoid bone (the latter two form the sphenopalatine foramen)

4d. Meatuses and Sinus Drainage

4e. Nasal Valves

• Bounded by: nasal septum, caudal edge of ULC, anterior face of inferior turbinate
• Forms a 10-15 degree nasal valve angle
• Narrowest cross-sectional area of the nasal cavity
• Site of greatest nasal airflow resistance
• Does NOT change dimension during inspiration

• Bounded by: nasal ala laterally, nasal septum and columella medially
• Situated caudal to the internal nasal valve
• Normally dilates during inspiration

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5. BLOOD SUPPLY

External Carotid Artery (via maxillary artery):

• Sphenopalatine artery - enters through the sphenopalatine foramen; the dominant supply to the posterior nasal cavity
• Greater palatine artery - supplies the anteroinferior septum via the incisive canal

Internal Carotid Artery (via ophthalmic artery):

• Anterior ethmoidal artery - supplies the anterosuperior nasal cavity
• Posterior ethmoidal artery - supplies the posterosuperior area

Kiesselbach's Plexus (Little's area)

Venous Drainage:

• Via ophthalmic and facial veins and the pterygoid and pharyngeal plexuses
• Intracranial drainage via the cavernous sinus through the ophthalmic vein - clinically important because of potential intracranial spread of nasal sepsis

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6. NERVE SUPPLY

Sensory Innervation:

Autonomic Innervation:

• Parasympathetic (secretomotor to glands, vasodilatory): postganglionic fibers from the pterygopalatine ganglion (synapse of greater petrosal nerve + deep petrosal nerve = Vidian nerve)
• Sympathetic (vasoconstrictive): postganglionic fibers from the superior cervical ganglion, traveling along the deep petrosal nerve

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7. LYMPHATIC DRAINAGE

• Anterior nose: drains to submandibular lymph nodes
• Posterior nose: drains to retropharyngeal and upper deep cervical lymph nodes

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8. PARANASAL SINUSES (Summary)

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9. NASAL FUNCTIONS

1. Airway - filters, warms, and humidifies inspired air
2. Olfaction - olfactory epithelium in the superior nasal cavity detects odors
3. Immunologic - mucociliary clearance removes pathogens and particles
4. Resonance - contributes to voice quality and speech
5. Nasolacrimal drainage - inferior meatus receives lacrimal secretions

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References