Nasal Anatomy: Structure and Cartilages

External Nasal Anatomy: General Structure

• External nose is a pyramid with the root located superiorly and the apex inferiorly
• The root of the nose merges with the anterior surface of the head
• The dorsum is defined as the area between the root and the apex
• The nares (nostrils) are inferior to the apex and are openings to the nasal cavity
• The nasal septum separates the nares
• The ala nasi (wings of the nostrils) laterally bound the nares

Bony and Cartilaginous Components of External Nose

• Bones shape the nose root
• Nasal, maxillae, and frontal bones form the bony nasal root
• The external nose's cartilaginous part consists of several cartilages

Alar Cartilages

• Major alar cartilage forms the apex of the nose
• Minor alar cartilages support the ala nasi

Lateral and Septal Cartilages

• Lateral nasal cartilage forms the dorsum of the nose
• Septal cartilage bounds the nares medially

Nasal Cavity Anatomy

• Two nasal cavities are located within the external nose and the adjacent skull
• The structure of the nasal cavity is influenced by 12 cranial bones

Anterior and Posterior Openings

• Nares are the anterior openings
• Choanae are the posterior openings that communicate with the nasopharynx

Nasal Cavity Roof

• The ethmoid bone forms the roof of the nasal cavity

Lateral Walls: Nasal Conchae

• The nasal cavity consist of three bony shelves (inferior, middle, and superior nasal conchae)
• These are attached to the lateral walls and project into the nasal cavities
• These divide the nasal cavities into four air channels

Air Channels: Nasal Meatuses and Recess

• Inferior nasal meatus is located between the floor and inferior concha
• Middle nasal meatus is located between the inferior and middle concha
• Superior nasal meatus is located between the middle and superior concha
• Sphenoethmoidal recess is located between the superior concha and the nasal cavity roof
• Common nasal meatus is located between the conchae and nasal septum

Nasal Cavity Regions

• Three regions include the vestibule, olfactory region, and respiratory region

Vestibule

• Located just inside the anterior external opening of the nose
• Contains hair follicles

Olfactory Region

• Small area
• Located inside at the superior apex of the cavity
• Lined by olfactory epithelium

Respiratory Region

• Remainder of the nasal cavity
• Largest region
• Lined with respiratory epithelium

Paranasal Sinuses

• Four bony recesses communicate with the nasal cavities and are named after the bones they are located in
• The paranasal sinuses are covered by respiratory mucosa and innervated by the trigeminal nerve (Cranial Nerve V)
• Sphenoidal sinus, maxillary sinus, frontal sinus, and ethmoidal cells

Blood Supply

• Blood supply to the vestibule, respiratory portion, and external nose (apex and dorsum)

External Carotid Artery Branches

• Sphenopalatine artery
• Greater palatine artery
• Superior labial artery
• Lateral nasal artery

Blood Supply to Olfactory Region

• Blood supply to the olfactory region and surrounding external nose is provided by internal artery branches
• Anterior and posterior ethmoidal arteries

Nerve Supply of the Nasal Cavity

• Three cranial nerves innervate the nasal cavity

Olfactory Nerve (CN I)

• Olfactory function

Trigeminal Nerve (CN V)

• General sensation

CN VII - Parasympathetic Fibers

• Innervate serous glands in the nasal mucosa

Sympathetic Innervation

• T1 level of spinal cord regulates blood flow through nasal mucosa