017 the nose and air sinuses Flashcards
what bones form the nasal cavity?
ethmoid
frontal
nasal
sphenoid
maxilla
palatines
inferior nasal concha
vomer
lacrimal
what are the nasal conchae?
- 3 bony shelves in the nasal cavity
- superior, middle and inferior concha
- contains openings for access to the frontal, sphenoid and maxillary sinus as well as the lacrimal duct
what is a?
frontal bone
what is b?
frontal sinus
what is c?
nasal bone
what is d?
septal cartilage
what is e?
palatine process of maxilla
what is f?
horizontal plate of palatine bone
what is g?
sphenoid bone
what is h?
vomer bone
what is I?
nasal septum : perpendicular plate of ethmoid bone
what is j?
sphenoid sinus
what is k?
crista galli
what bones make up the nasal conchae?
superior and middle = ethmoid bone
inferior = separate own bone
beneath each concha is a meatus ( a pocket)
what are the paranasal air sinuses?
- frontal sinus, ethmoid air cells, sphenoid sinus, maxillary sinus
- due to bones of the facial skull being pneumatised (contain air sinuses)
- can be very irregular in shape
- drain into the nasal cavity
where do the paranasal air sinuses drain into?
the nasal cavity
why is the sphenoid air sinus clinically important?
- it is a surgical access for the pituitary fossa/ sella tercica
describe some features of the maxillary sinus
- largest of all sinus
- between the floor of the orbit and the alveolar bone of the maxilla
- walls are paper thin
- tooth roots sometimes protrude into the sinus space
- drainage is in a superior position on the sinus cavity
describe the mucosa lining the air sinuses
- respiratory mucous membrane
- rich in mucous and serous glands
- mucous traps dust, bacteria and other particles
- nasal vestibule is lined with squamous epithelial mucous membrane
- past the vestibule it is lined with ciliated respiratory epithelium
- highly vascularised and innervated
where does the sphenoid sinus drain to?
- towards superior meatus
2 - two openings into the spheno-ethmoidal recess
where do the posterior ethmoidal air cells drain to?
-towards superior meatus
3 - superior nasal meatus
where does the frontal sinus drain to?
- towards middle meatus
1 - via infundibulum to the front of semilunar hiatus, anterior to superior concha
where do the middle ethmoidal air cells drain to?
- towards middle meatus
open onto the ethmoidal bulla
where do the anterior ethmoidal air cells drain to?
- towards middle meatus
4 - into the ethmoidal infundibulum or frontonasal duct
where does the maxillary sinus drain to?
- towards middle meatus
5 - via ostium to the semilunar hiatus
where does the nasolacrimal duct drain to?
- towards the inferior meatus
6
what is a?
ethmoid bulla
- opening of the middle ethmoid sinus
what is b?
opening of sphenoid sinus
what is c?
opening of eustachian tube
what is d?
opening of nasolacrimal duct
what is e?
semilunar hiatus
- openings of frontal, maxillary and anterior ethmoidal sinuses
what is sinusitis?
inflammation/infection of the air sinuses
- common complication following upper respiratory tract infections
- mucous of lining gets inflamed and swells up, blocking the drainage of the sinus space
- this builds up pressure and can become painful
which air sinus do tumours most often occur
- maxillary sinus
what causes tumours in air sinuses?
- smoking
- air pollution
- carpenters/builders exposure to chemicals and irritants
describe the blood supply to the paranasal sinuses
- superior half = internal carotid artery –> ophthalmic artery –> ethmoidal arteries
- inferior half = external carotid artery –> maxillary artery –> sphenopalatine arteries
- both anastomose at the anterior part of nose
describe the blood drainage of the paranasal sinuses
- superior half = ethmoidal veins –> ophthalmic veins –> cavernous sinus and internal jugular vein
- inferior half = sphenopalatine veins –> maxillary vein –> retromandibular and internal and external jugular veins
+ facial vein
what is epistaxis?
nosebleeds
what causes epistaxis/nosebleeds?
- high blood pressure can burst the plexus’ in the nose
- anterior = Kisselbach’s plexus between the ethmoid and sphenopalatine arteries
- posterior = Woodruff’s plexus on the posterior part of the inferior meatus (more serious, harder to control)
describe the lymph drainage of the nasal cavity
- posterior = drainage to the retropharyngeal nodes
- anterior drainage to the upper cervical or submandibular nodes
- both end up draining to the deep cervical nodes
what is the nasal vestibule?
small dilated space just inside the nasal openings lined by skin and hair follicles
what are the respiratory regions of the nose?
largest part of the nasal cavity
- rich neurovascular supply
- lined by respiratory epithelium
middle concha and below
what are the olfactory regions of the nose?
apex of nasal cavity
- superior concha
- lined by olfactory epithelium and receptors
what are the 3 cranial nerves that innervate the nasal cavity?
- olfactory CNI
- trigeminal CNV (i and ii)
- facial CNVII
what does the ophthalmic division of the trigeminal nerve supply in the nasal cavity?
- the nasociliary nerve of the ophthalmic division supplies the outer skin of the back of the nose via the anterior ethmoid nerve
- anterior ethmoid nerve also supplies the mucous membrane of the anterior (vestibular) part of the nose
- the posterior ethmoid nerve (branch of nasociliary) supplies the mucous membrane of the sphenoid and frontal sinus and upper anterior part of nasal mucousa
what does the maxillary division of the trigeminal nerve supply in the nasal cavity?
- nasopalatine nerve via the sphenopalatine foramen supplies the roof and lateral wall of the nose
- superior alveolar nerves supply mucousa of posterior nasal cavity and septum, palate, maxillary sinus and gingiva of the maxilla
- infraorbital nerve supplies the skin of lateral part of nose
- posterior nasal nerves
- originate in pterygopalatine fossa
what does the facial nerve supply in the nasal cavity?
- innervates muscles that move the nose
- greater petrosal nerve branch supplies lacrimal gland and mucous glands of nose and palate
- fibres join with maxillary division in the pterygopalatine fossa at the pterygo-palatal ganglion
what does the olfactory nerve supply in the nasal cavity?
- sense of smell
- based on chemoreception
- volatile odorants are trapped in mucous on the nasal conchae surface and interact with chemoreceptors
- highly regenerative neurons
- olfactory bulb sits above cribriform plate of ethmoid bone and branches go down into nasal cavity
what is the pterygomaxillary fissure?
- the slit between the sphenoid and maxilla where bones do not meet
- deep within this fissure is palatine bone
- deepest part of fissure called pterygopalatine fossa
- contains many nerves and blood vessels to the nose
where is the ostium/opening of the maxillary sinus?
- high on lateral wall of nose beneath the middle concha at the front of the hiatus semilunaris
- the hiatus runs around base of swellings formed by bulging of some ethmoidal air cells (ethmoidal bulla)
what is the roof of the nasal cavity?
frontal, nasal and ethmoid bone (cribriform plate) anteriorly and sphenoid bone posteriorly
what is the floor of the nasal cavity?
palatine bone of the maxilla
horizontal plate of palatine bone
what forms the walls of the nasal cavity?
nasal septum = ethmoid perpendicular plate dividing the 2 nostrils
vomer bone = beneath ethmoid plate
lacrimal bone
maxilla
perpendicular plate of palatine bone
septal and alar cartilage on tip of nose
concha
