25 - Nasal cavity Flashcards
Describe the overall structure of the nasal cavity.
- paired structure with right and left cavities separated by the septum
- separated form the oral cavity by the hard palate
What is the function of the nasal cavity?
- contain olfactory receptor for smell
- filters and humidifies air for respiration
What bones make up the external nose?
- nasal
- frontal process of maxilla
What cartilages make up the external nose?
- septal
- major and minor alar
What muscles make up the external nose?
- nasalis
- depressor septi nasi
- Levator labii superioris alequae nasi
What bone forms the floor of the nasal cavity?
- palatine process of maxillae
- horizontal plate of palatine bones
What are the key features of the floor of the nasal cavity?
- nares
- incisive canals
- nasal crest
What are the nares?
Anterior opening of the nasal cavity (nostrils)
What is the nasal crest?
Attachment of the vomer in the nasal septum
What makes up the nasal septum?
- septal cartilage
- perpendicular plate of ethmoid bone
- vomer
What problems can a deviated septum present?
- can be a birth defect or caused by injury
- snoring
- nosebleeds
- difficulty bleeding
What makes up the roof of the nasal cavity?
- cribriform plate of ethmoid
- nasal bones (anteriorly)
- nasal spine of frontal bone (anteriorly)
- sphenoid bone (posteriorly)
What is the cribriform plate’s relationship to the nasal cavity?
Has many holes to allow the passage of the olfactory nerves to the nasal cavity
What bones make up the lateral wall of the nasal cavity?
- nasal
- ethmoid (superior and middle conchae)
- lacrimal
- maxilla
- inferior concha
- palatine
- sphenoid
What is the ethmoidal labyrinth?
- projects 2 of the 3 conchae in the nose
- middle and superior
- lateral walls of the labyrinth form part of the orbit
- increases surface area for warming and humidification
What is the function of the conchae?
Increase surface area for warming and humidification of the air
What are the meatus in the nasal cavity?
- area under the conchae
- named respectively
Describe the pattern of innervation of the nasal cavity.
- olfactory nerve (CN I) innervates the area over the superior concha
- CN V1 innervates the upper/anterior portion of the lateral wall and septum
- CN V2 innervates the lower/posterior portion of the lateral wall and septum
What branches of CN V1 innervate the nasal cavity?
Anterior ethmoidal (branch of infratrochlear)
What branches of CN V2 innervate the nasal cavity?
- anterior superior alveolar nerve (nasal branch)
- infraorbital nerve (nasal branch)
- nasopalatine nerve
- lateral nasal nerves (posterior inferior and posterior superior)
What nerve supplies the Ala of the nose?
Infraorbital nerve
Describe the arterial supply of the nasal cavity.
ECA
- sphenopalatine (maxillary)
- greater palatine (maxillary, from oral cavity)
- superior labial (facial)
- lateral nasal (facial)
ICA (ophthalmic)
- anterior ethmoidal
- posterior ethmoidal
Describe the venous drainage of the nasal cavity.
- veins that follow the maxillary artery drain into the pterygoid plexus
- veins that follow the facial artery drain into the facial vein
- veins that follow the ethmoidal arteries drain into the cavernous sinus
Name the paranasal sinuses.
- frontal
- ethmoidal cells
- sphenoid
- maxillary
What are paranasal sinuses?
Hollow cavity in bone within the skull that are lined by respiratory epithelium and open into the nasal cavity
Describe the drainage of the ethmoidal cells.
- anterior cells drain into the infundibulum in middle meatus
- middle cells drain into middle meatus at the ethmoidal bulla
- posterior cells drain into superior meatus
Describe the drainage of the maxillary sinus.
Drains into the middle meatus at the semilunar hiatus
Describe the drainage of the frontal sinus.
Drains into the infundibulum in the middle meatus
Describe the drainage of the sphenoid sinus.
Drains into the sphenoethmoidal recess in the superior, posterior aspect of the nasal cavity
Why does infection in the sinuses mimc toothache?
- similar innervation
- build up of infected material (pus), cannot drain as exit is superior
