Unit 3 Flashcards
what 2 things make up the external nose?
bone and hyaline cartilage
The lateral boundary of the external nasal aperture (naris) is formed by……… posteriorly and the major ……..e anteriorly.
The lateral boundary of the external nasal aperture (naris) is formed by fibrofatty tissue posteriorly and the major alar cartilage anteriorly.
whats the vestibule of the nose?
The hairy skin of the external nose extends into the nasal cavity for a short distance and is known as the vestibule of the nose.
describe how the nasal cavity is divided into 2
The nasal cavity is divided into left and right halves by the nasal septum, which forms its medial walls.
The septum is formed by the perpendicular plate of the ethmoid superiorly, by the vomer posteriorly and by cartilage anteriorly.
describe the roof of the nasal cavity
The roof is arched, and is formed anteriorly by the nasal bones, in the middle by the cribriform plate of the ethmoid, and posteriorly by the inferior surface of the body of the sphenoid
Olfactory nerves pass through the ……to reach the olfactory bulb.
Olfactory nerves pass through the cribriform plate to reach the olfactory bulb.
describe the floor of the nasal cavity
The floor consists of the palatine processes of the maxillae anteriorly, and the horizontal plates of the palatine bones posteriorly.
describe the lateral walls of the nasal cavity
The lateral wall is formed mainly by the maxilla and three conchae. The superior and middle conchae are part of the ethmoid, while the inferior concha is a separate bone.
what are the conchae
The conchae are large, medially-directed bony elements covered by highly vascular mucous membranes. Air is heated and humidified as it is drawn past the conchae during breathing. Beneath each shelf-like concha is a meatus into which the paranasal sinuses open
what are paranasal sinuses?
Paranasal sinuses are a group of four paired air-filled spaces that surround the nasal cavity.
lateral wall of the nasal cavity
does the nosa have a very rich blood supply?
yep
which carotid artery does the nose recieve blood from?
BOTh internal and external
main blood supply for the nasal cavity comes from
a branch of the maxillary artery, the sphenopalatine artery.
The other arteries that contribute are the anterior ethmoidal branch of the ophthalmic artery and the labial branch of the facial artery.
describe venous drainage from the nasal cavity
Venous blood leaves the region in veins that course alongside the arteries, and drain into the facial, ophthalmic, and sphenopalatine veins.
The latter form part of the pterygoid plexus of veins in the infratemporal fossa.
describe the mucous membrane present in the nasal cavity
The olfactory part, which is responsible for smell, is in the roof and adjacent parts of the medial and lateral walls, and is covered by columnar epithelium.
The rest is respiratory epithelium, except for the vestibule, which is lined with stratified squamous epithelium.
describe where olfactory axons originate
Olfactory nerves come from cell bodies in the olfactory mucous membrane, and pass through openings in the cribriform plate of the ethmoid bone
what maintains general sensation of the nasal cavity
General sensation is mediated by branches of the ophthalmic and maxillary divisions of the trigeminal nerve which accompany the vascular supply.
describe the nervous supply to the mucous glands
Parasympathetic secretomotor supply to the mucous glands is mediated by postganglionic fibres from the pterygopalatine ganglion.
The preganglionic fibres are carried by the greater petrosal nerve, a branch of the facial nerve.
innervation of the external skin of the nose?
nnervation to the external skin of the nose is supplied by the trigeminal nerve.
whats anosmia
loss of sense of smell
problems of a cribriform plate fracture
what are paranasal sinuses (U3 definintion)
These are a series of membrane-lined cavities within the facial bones.
each paranasal sinus is lined by?
Each sinus is lined with ciliated mucous columnar epithelium
describe how liliary curretns are directed out of the paranasal sinuses
The ciliary currents are directed spirally towards the openings of the sinuses. Each sinus is named by the bone in which it lies.
functions of paranasal sinuses
They are centered on the nasal cavity and have various functions, including lightening the weight of the head, humidifying and heating inhaled air, increasing the resonance of speech, and serving as a crumple zone to protect vital structures in the event of facial trauma.
describe the frontal sinus
This lies above the orbit and can be quite extensive. It communicates with the nasal cavity by an opening in the anterior end of the middle meatus.
green on image
how does the frontal sinus drain?
via the frontonasal duct, which opens into the hiatus semilunaris, within the middle meatus of the nasal cavity.
what supplies sensation to the frontal sinus
Sensation is supplied by the supraorbital nerve (a branch of the ophthalmic nerve)
arterial supply of the frontal sinus
arterial supply is via the anterior ethmoidal artery (a branch of the internal carotid).(and wiki syas the anterior ethmoidal artery)
where does the maxillary sinus lie?
It lies lateral to the nasal cavity, above the upper molar teeth.