Anatomy: Nasal Cavity & Paranasal Sinuses Flashcards
Nose features
- Pyramidal
- Root = upper end
- Apex = free tip
- Dorsum = extends from root to apex, in midline
- 2 inferior apertures, the nares/nostrils
- Each nostril is limited laterally by ala of nose
Supporting framework of nose is composed of what?
- Bone
- Hyaline cartilage
What does the bony framework support, and what does it consist of?
- Upper part of the nose
- Consists of nasal bones and frontal processes of maxillae
What does the cartilaginous framework support and consist of?
- Supports the lower part of the nose
- Consists of 3 major pieces:
- -1 Septal cartilage
- -2 Major alar cartilages
How are the cartilages connected to each other and bones?
By fibrous tissue
Forms anterior part of the nasal septum; has 2 lateral processes (triangular in shape, located below inferior border of nasal bones)
Septal cartilage
U-shaped; form lateral and medial borders of nostrils (lateral and medial crura, respectively)
Major Alar Cartilages
Chamber consisting of bony and cartilaginous walls, covered with mucosa
Nasal cavity
Parts of nasal cavity
- Floor
- Roof
- 2 lateral walls
- Midline partition (nasal septum)
- Opens anteriorly on face via nares/nostrils
- Vestibule
Functions of nasal cavity
- Olfaction (sense of smell)
- Conditioning of inspired air (filtration, humidification, warming) to the alveoli
- Reception of secretions from paranasal air sinuses and nasolacrimal duct
SUPERIOR Nasal cavity relationships
Anterior cranial fossa (separated by the cribriform plate)
LATERAL TO UPPER PART OF Nasal cavity relationships
- Ethmoidal air cells
- Orbit
LATERAL TO LOWER PART OF Nasal cavity relationships
Maxillary sinus
INFERIOR Nasal cavity relationships
Oral cavity (separated by hard palate)
POSTERIOR Nasal cavity relationships
Nasopharynx (communicates via choanae)
Composition of bony walls: FLOOR
-Hard palate
Palatine processes of maxillae and horizontal plates of palatine bones
Composition of bony walls: ROOF
(From anterior to posterior)
- Nasal bone
- Nasal spine of frontal bone
- Cribiform plate of ethmoid bone
- Anterior and Inferior aspects of body of sphenoid bone
Composition of bony walls: MEDIAL WALL (NASAL SEPTUM)
- Perpendicular plate of ethmoid bone
- Vomer
- Smaller contributions from sphenoid, maxilla, and palatine
Composition of bony walls: LATERAL WALL
- Maxilla
- Lacrimal bone
- Inferior nasal concha
- Ethmoidal labyrinth
- Perpendicular plate of palatine bone
- Medial pterygoid plate
- 3 nasal meatuses (spaces b/w each concha and lateral wall)
- -Superior
- -Middle
- -Inferior
Part of nasal cavity located above and behind superior nasal concha
Sphenoethmoidal recess
Communications of SUPERIOR NASAL MEATUS
Posterior ethmoidal air cells open via small orifices in its lateral wall
Communications of MIDDLE NASAL MEATUS
- Ethmoidal Bulla
- Semilunar hiatus
- Ostium (opening) of maxillary sinus located in lower part of semilunar hiatus
- Superior end of semilunar hiatus leads into a curved channel known as the infundibulum
Elevation in lateral wall of middle meatus caused by middle ethmoidal air cells
Ethmoidal Bulla
openings of middle ethmoidal air cells are found on ethmoidal bulla
Curved cleft anterior and inferior to ethmoidal bulla
Semilunar hiatus
Receives openings of anterior ethmoidal air cells; Superior end of semilunar hiatus leads into this curved channel
Infundibulum
In different individuals, what can the infundibulum also receive?
- In some individuals, it also receives openings of frontal sinus
- In others, it has superior blind end, and the frontal sinus opens directly into anterior part of middle nasal meatus
Communications of INFERIOR NASAL MEATUS
Opening of nasolacrimal duct is located in anterior part of its lateral wall
Communications of SPHENOETHMOIDAL RECESS
Opening of sphenoidal sinus
Lines entire nasal cavity, except vestibule
Nasal mucosa
Firmly bound to periosteum and perichondrium of supporting structures
Nasal mucosa
Continuous with lining of nasopharynx, paranasal air sinuses, and nasolacrimal duct
Nasal mucosa
Types of mucosa
- Olfactory mucosa
- Respiratory mucosa
Type of mucosa that lines the highest part of the roof and adjacent parts of the septum and lateral wall; contains olfactory receptor cells
Olfactory mucosa
Type of mucosa that lines the rest of the nasal cavity [respiratory epithelium (ciliated, pseudostratified, columnar epithelium)]
Respiratory mucosa
The general sensory nerve supply of the nasal cavity is derived from what?
- Branches of the ophthalmic nerve (V1)
- Branches of the maxillary nerve (V2)
General sensory nerves of the nasal cavity
- Anterior ethmoidal nerve
- Nasal branches of infraorbital nerve
- Nasal branches of anterior superior alveolar nerve
- Posterolateral nasal branches
- Nasopalatine nerve
The Anterior Ethmoidal Nerve is a branch of what?
Of the nasociliary nerve (from the ophthalmic nerve [V1])
Path of anterior ethmoidal nerve
- Passes from orbit to anterior cranial fossa via anterior ethmoidal foramen
- Runs forward on cribriform plate
- Leave anterior cranial fossa
- Enters nasal cavity via small slit at side of crista galli
- Divides into 2 branches (internal and external nasal branches)
What are the two branches the anterior ethmoidal nerve branches into?
- Internal Nasal Branch
- External Nasal Branch
What does the internal branch of the anterior ethmoidal nerve supply?
Mucosa of anterior parts of septum and lateral wall
What does the external nasal branch of the anterior ethmoidal nerve supply?
Skin of lower part of nose
What does the NASAL BRANCH OF INFRAORBITAL NERVE of the general nerve supply of the nasal cavity supply?
Skin of vestibule
What does the NASAL BRANCH OF THE ANTERIOR SUPERIOR ALVEOLAR NERVE of the general nerve supply of the nasal cavity supply?
Mucosa of anterior part of inferior meatus
Where do the POSTEROLATERAL NASAL BRANCHES of the general sensory nerve supply of the nasal cavity originate and what do they supply?
- Originate from pterygopalatine ganglion or greater palatine nerve
- Supply mucosa of posterior part of lateral wall
What does the NASOPALATINE NERVE of the general nerve supply of the nasal cavity supply?
Mucosa of posterior part of nasal septum
Special sensory nerve supply of the nasal cavity
- Olfactory receptor cells are bipolar neurons located in olfactory mucosa
- Peripheral processes (dendrites) reach mucosal surface and give rise to nonmotile cilia, which spread over mucosal surface
- Central processes (axons) join to form olfactory nerves
What is the path for the central processes (axons) joining to form the olfactory nerves?
- Pass through the openings of the cribriform plate
- End in olfactory bulb
Main arterial sources in the nasal cavity
- Sphenopalatine artery
- Anterior ethmoidal artery
Minor arterial sources of the nasal cavity
- Posterior ethmoidal artery
- Superior labial artery (branch of facial artery [CN VII])
- Greater palatine artery
Site at which the septal branches of sphenopalatine, greater palatine, anterior ethmoidal, and superior labial arteries anastomose
Kiesselbach’s area
Common site of epistaxis (nosebleeds)
Kiesselbach’s area
Kiesselbach’s area is the site where which arteries anastomose?
Septal branches of:
- Sphenopalatine
- Greater palatine
- Anterior ethmoidal
- Superior labial arteries anastomose
Forms a rich plexus in the submucosa
Veins of the nasal cavity
Places of venous drainage
- Into pterygoid venous plexus (via sphenopalatine vein)
- Into facial vein
- Into superior ophthalmic vein (via anterior and posterior ethmoidal veins)
Air spaces in frontal, maxilla, ethmoid, and sphenoid bones, lined by a mucous membrane continuous with that of nasal cavity
Paranasal sinuses
How do sinuses develop?
- As evaginations of nasal mucosa
- Mucosa invades bones surrounding nasal cavity, with secondary bone resorption around invading mucosal sacs
What are sinuses like at birth?
- Sinuses are rudimentary (baby’s don’t have them)
- There’s a slow, continuous growth during childhood and a rapid growth during adolescence
- Sinuses attain maximum size in adult
Functions of paranasal sinuses
- Resonating chambers for voice
- Lighten skull bones
Largest of paranasal sinuses
Maxillary sinus
Where does the maxillary sinus lie?
Within the body of the maxilla
Shape of the maxillary sinus
- Roughly pyramidal shape
- Base: directed medially, toward nasal cavity
- Apex: directed laterally, toward zygomatic bone
SUPERIOR Relationship of the Maxillary Sinus
Orbit and its contents (infraorbital canal runs along superior wall of sinus and creates a bony ridge)
MEDIAL Relationship of the Maxillary Sinus
Nasal cavity (maxillary ostium/opening located high in medial wall, poor drainage in erect posture)
INFERIOR Relationship of the Maxillary Sinus
- Maxillary alveolar process
- Roots of maxillary teeth (molar roots are closer to maxillary sinus than incisor roots)
What does the maxillary sinus communicate with?
Middle nasal meatus
What is the middle nasal meatus
-Opening located in lower part of semilunar hiatus
Nerve supply for the maxillary sinus
Superior alveolar nerves (from V2)
Blood supply for maxillary sinus
Superior alveolar arteries (branches of maxillary and infraorbital arteries)
Sinus that is located within the frontal bone, behind the superciliary arches; Vary in size and are rarely symmetrical
Frontal sinus
Path of frontal sinus
- Usually extend superiorly into frontal squama and posteriorly into orbital plates (roof of orbit)
- Open into middle nasal meatus
Nerve supply for the frontal sinuses
Supraorbital nerve (branch of frontal nerve, from V1)
Blood supply for the frontal sinuses
Supraorbital artery (branch of ophthalmic artery)
Thin-walled spaces within ethmoidal labyrinths; Number of cells varies from 3 to 18; “Bubbly, crunchy, air-filled cells”
Ethmoidal Air Cells
Where do the ANTERIOR ethmoidal air cells open into?
Infundibulum of middle nasal meatus
Where do the MIDDLE ethmoidal air cells open into?
On surface of ethmoidal bulla of middle nasal meatus
Where do the POSTERIOR ethmoidal air cells open into?
Into superior nasal meatus
Nerve supply for the ethmoidal air cells
Anterior and posterior ethmoidal nerves (branches of nasociliary nerve, from V1)
Blood supply for the ethmoidal air cells
Anterior and posterior ethmoidal arteries (branches of ophthalmic artery)
Sinus located posterior to the upper part of the nasal cavity, within the body of the sphenoid bone; Vary in size and are rarely symmetrical
Sphenoidal sinus
Where are the sphenoidal sinuses related to SUPERIORLY?
- Pituitary gland
- Optic chiasm
What are the sphenoidal sinuses related to LATERALLY?
- Cavernous sinus
- Internal carotid artery
What do the sphenoidal sinuses open into?
Corresponding sphenoethmoidal recess
Nerve supply for the sphenoidal sinus
- Posterior ethmoidal nerve (branch of nasociliary nerve, from V1)
- Pharyngeal nerve (from pterygopalatine ganglion, contains V2 sensory fibers)
Blood supply for the sphenoidal sinus
- Posterior ethmoidal artery (branch of ophthalmic artery)
- Pharyngeal branch of maxillary artery
