Anatomy of the Nose Flashcards
What makes up the skeleton of the external nose?
Mainly cartilaginous
Where is the dorsum of the external nose located?
Extends from root of the nose to its tip
What are the nares?
Nostrils = bound laterally by alae of nose, pierce inferior surface of nose
What is different about the skin over the nasal cartilage?
Thicker than skin over nasal bone and contains sebaceous glands
What are vibrissae?
Stiff hairs of the nasal vestibule = usually moist, filter dust particles form air entering the nasal cavity
Where is the junction of the skin and the mucous membrane of the external nose?
Junction is beyond the hair bearing area of the vestibule
What are the cartilaginous components of the external nose?
Two lateral cartilages, two alar cartilages, one septal cartilage
What are the alar cartilages of the external nose?
U shaped, free and moveable cartilage = dilate or constrict nares when nasal muscles contract
What does the nasal septum do?
Divides the chamber of the nose into two cavities = has bony part and soft mobile cartilaginous parts
What are the main components of the nasal septum?
Perpendicular plate of the ethmoid bone, vomer, septal cartilage
What part of the nasal septum does the perpendicular plate of the ethmoid bone form?
Forms superior part of septum (thin plate) = descends from cribriform plate
What is the perpendicular plate of the ethmoid bone continued superiorly as?
The crista galli
What part of the septum does the vomer make?
Postero-inferior part (thin flat bone)
What structures contribute to the vomer?
The nasal crest of the maxillary and palatine bones
What kind of articulation does the septal cartilage have with the bony cartilage of the nasal septum?
Tongue-and-groove articulation
What is the anterior entrance to the nasal cavity?
The nares
What is the posterior opening of the nasal cavity into the nasopharynx?
Enters through the chonae
What lines the nasal cavity?
Mucosa = exception is vestibule, which is lined by skin
What is the mucosa of the nasal cavity bound to?
Firmly bound to the periosteum and perichondrium of the supporting bones and cartilages of the nose
What are the structures that the nasal cavity communicates with?
Nasopharynx posteriorly, paranasal sinuses superiorly and laterally, lacrimal sac and conjunctiva superiorly
How is the mucosa of the nasal cavity divided?
Inferior 2/3 of mucosa is the respiratory area, superior 1/3 is olfactory area
What is the function of the respiratory area of the nasal cavity mucosa?
Warms and moistens air
What are the features of the roof of the nasal cavity?
Curved and narrow (except at posterior sphenoidal end), has three parts named for the bone that forms each
What are the parts of the roof of the nasal cavity?
Frontonasal, ethmoidal, sphenoidal
What forms the floor of the nasal cavity?
Palatine process of the maxilla and the horizontal plates of the palatine bone (floor is wider than roof)
Why are the lateral walls of the nasal cavity irregular?
They have three nasal conchae projecting inferiorly
How many nasal conchae are there?
Three = superior, middle and inferior
What advantages do the nasal conchae convey in thermoregulation?
Offer vast surface area for heat exchange = curve inferomedially and hang like curtains
Where is the superior nasal conchae located?
Anterior to the sphenoidal sinus
What are some features of the middle nasal conchae?
Has angled inferior border and ends inferior to the sphenoidal sinus
Where is the sphenoidal sinus located?
Occupies the body of the sphenoid bone
Where does the sphenoid sinus open into?
Its orifice (superior to middle of its anterior wall) opens into the spheno-ethmoidal recess
Where do the posterior, middle and anterior ethmoidal cells open into?
The superior meatus, middle meatus and semilunar hiatus respectively
Where does the inferior nasal concha end?
Inferior to the middle concha about 1cm anterior to the orifice of the Eustachian tube
What underlies each nasal conchae?
A nasal meatus
What passages are present in the nasal cavity?
Spheno-ethmoidal recess posterosuperiorly, three nasal meatus, common nasal meatus medially
What is the common site of opening of the spheno-ethmoidal recess and the three nasal meatus?
The common nasal meatus
Where is the spheno-ethmoidal recess located?
Superoposterior to the superior nasal concha
What opens into the spheno-ethmoidal recess?
The sphenoid sinus = air filled cavity in body of sphenoid
Where does the posterior ethmoid sinuses open into?
The superior nasal meatus
How does the middle nasal meatus communicate with the frontal sinus?
Through the ethmoidal infundibulum
What is the frontonasal duct?
Passage leading inferiorly from each frontal sinus to the infundibulum
What is the semilunar hiatus?
Semi-circular groove into which the frontal sinus opens into
What is the ethmoidal bulla?
Rounded elevation located superior to the semilunar hiatus = visible when middle nasal concha is removed
What forms the ethmoid bulla?
By the middle ethmoid cells that form the ethmoid sinuses
What does the nasolacrimal duct drain?
Drains tears from the lacrimal gland
Where does the nasolacrimal duct open into?
The anterior part of the inferior nasal meatus
Where is the common nasal meatus located?
Medial part of nasal cavity between the conchae and nasal septum
Where is the submucosal venous plexus located?
Deep to nasal mucosa of the nasal cavity
What veins drain into the submucosal venous plexus?
Sphenopalatine, facial and ophthalmic veins
What is the function of the submucosal venous plexus?
Exchanges heat and warms air before it enters the lungs
Where does venous blood from the external nose drain into?
Mostly into the facial vein via the angular and lateral nasal veins
What is the innervation of the postero-inferior portion of the nasal mucosa?
Mainly by maxillary nerve (CN V2)
What nerve innervates the mucosa of the nasal septum?
Nasopalatine nerve
What nerves supply the mucosa of the lateral walls of the nasal cavity
Posterior superior lateral nasal and inferior lateral nasal branches of the greater palatine nerve
What nerve supplies the anterosuperior portion of the nasal mucosa?
Mainly from the ophthalmic nerve (CN V1) = anterior and posterior ethmoidal nerves
What nerve are the anterior and posterior ethmoidal nerves branches of?
The nasociliary nerve
What nerve supplies the dorsum and apex of the external nose?
CN V1 = infratrochlear nerve and external nasal branch of the anterior ethmoidal nerve
What nerve supplies the alae of the nose?
Nasal branches of the infra-orbital nerve (CN V2)
Where do the olfactory nerves arise from?
The olfactory epithelium in the superior part of the lateral and septal walls of the nasal cavity
What forms the olfactory nerve?
The central processes of olfactory cells = pass through cribriform plate and end in the olfactory bulb
What is the olfactory bulb?
Rostral expansion of the olfactory tract
What are the paranasal sinuses?
Air filled extensions of the respiratory part of the nasal cavity
Where are the frontal sinuses located?
Right and left sinuses are between the outer and inner tables of the frontal bone, posterior to the superciliary arches and the roof of the nose
Where do the frontal sinuses drain into?
Each drain through the frontonasal duct into the ethmoidal infundibulum (which opens into the semilunar hiatus)
What innervates the frontal sinuses?
Branches of the supra-orbital nerves (CN V1)
What are the two parts of the frontal sinus?
Vertical part in squamous part of frontal bone and horizontal part in orbital part of frontal bone
What are the ethmoidal cells?
Small invaginations of the mucous membranes of the middle and superior meatus
Where do the anterior ethmoidal cells drain into?
Drain into middle meatus through the ethmoidal infundibulum
Where do the middle ethmoidal cells open into?
Open directly into middle meatus
What do the middle ethmoidal cells form?
The ethmoid bulla = are sometimes called bullar cells
Where do the posterior ethmoidal cells drain into?
Open directly into the superior nasal meatus
What is the innervation of the ethmoidal cells?
Anterior and posterior ethmoidal branches of the nasociliary nerves (CN V1)
Why is the body of the sphenoid bone fragile?
It is extensively pneumatised
Where are the sphenoidal sinuses located?
In the body of the sphenoid but may extend to wings = unevenly divided and separated by a bony septum
What separates the sphenoid sinuses from important structures?
Thin plates = optic nerves and chiasms, pituitary gland, internal carotid arteries, cavernous sinuses
What are the sphenoidal sinuses derived from?
Derived from the posterior ethmoidal cell that begins to invade the sphenoid bone at age 2
What supplies the sphenoidal sinuses?
Posterior ethmoidal arteries and nerves
What are the largest paranasal sinuses?
The maxillary sinuses = paired pyramidal sinuses
What drains the maxillary sinus?
Drained via the maxillary ostium into the ethmoidal infundibulum, then through the semilunar hiatus into the middle nasal meatus
What is the arterial supply to maxillary sinus?
Superior anterior, middle and posterior alveolar arteries, infra-orbital artery, greater palatine artery
What nerves provide sensory innervation to the maxillary sinuses?
Posterior superior, middle superior and anterior superior alveolar nerves, infra-orbital nerve
Where is the opening to the sphenoidal sinus?
In the sphenoidal recess
What structure do the posterior ethmoidal sinuses open in to?
The superior meatus
Which meatus does does the nasolacrimal duct open in to?
Anterior part of the inferior meatus
Where does the apex of the maxillary sinus extend to?
The zygomatic bone
What is the maxillary ostium?
Opening of the maxillary sinus into the semilunar hiatus (then opens into middle meatus)
