Anatomy - Week 3 - Nose

What structures form the uppermost part of the respiratory tract?

Nasal cavities

What special receptors are housed in the nasal cavities?

Olfactory receptors

What is the overall shape of the nasal cavities?

Elongated, wedge-shaped spaces

What forms the base of the nasal cavity?

Large inferior base

What forms the apex of the nasal cavity?

Narrow superior apex

What provides primary support for the nasal cavity walls?

Skeletal framework of bone and cartilage

What is the anterior aperture of the nasal cavity?

Nares (nostrils)

What is the posterior aperture of the nasal cavity?

Choanae

What structure separates right and left nasal cavities?

Midline nasal septum

What separates the nasal cavity from the oral cavity below?

Hard palate

What bones separate the nasal cavity from the cranial cavity above?

Frontal, ethmoid, and sphenoid bones

What structures are located lateral to the nasal cavities?

Orbits

How many walls does each nasal cavity have?

Four: roof, floor, medial wall, lateral wall

What are the bone shelves projecting medially from the lateral wall?

Nasal conchae

How many nasal conchae are there?

Three: superior, middle, and inferior conchae

What is the orientation of the nasal conchae?

Project medially and inferiorly

What edges of the nasal conchae are free?

Medial, anterior, and posterior margins

What is the functional purpose of nasal conchae?

Increase surface area for air contact with mucosa

What are the air channels created by the conchae called?

Meatuses

What air channel lies between the inferior concha and nasal floor?

Inferior nasal meatus

What air channel lies between the inferior and middle concha?

Middle nasal meatus

What air channel lies between the middle and superior concha?

Superior nasal meatus

What air channel lies between the superior concha and roof?

Spheno-ethmoidal recess

What openings are found on the lateral wall of the nasal cavity?

Paranasal sinuses and nasolacrimal duct

What is the function of paranasal sinus openings?

Communication between sinuses and nasal cavity

What is the function of the nasolacrimal duct?

Drainage of tears into nasal cavity

What are the three general regions of the nasal cavity?

Nasal vestibule, respiratory region, olfactory region

Where is the nasal vestibule located?

Just internal to the naris

What lines the nasal vestibule?

Skin with hair follicles

What is the function of nasal vestibule hairs?

Filter large particles from air

What is the largest region of the nasal cavity?

Respiratory region

What type of blood supply does the respiratory region have?

Rich neurovascular supply

What epithelium lines the respiratory region?

Respiratory epithelium (ciliated and mucous cells)

What is the main function of the respiratory region?

Warming, humidifying, and filtering inhaled air

What region is at the apex of the nasal cavity?

Olfactory region

What lines the olfactory region?

Olfactory epithelium

What special receptors are found in the olfactory region?

Olfactory receptors for smell

What function of nasal cavities relates to smell?

Housing olfactory receptors

What function of nasal cavities relates to air conditioning?

Adjusting temperature and humidity of respired air

How do nasal cavities adjust temperature and humidity?

Through rich blood supply

What function of nasal cavities relates to filtration?

Trapping and removing particulate matter

How does the nasal vestibule filter air?

By hair in the nasal vestibule

How does the respiratory region filter air?

By mucus capturing foreign material

How are trapped particles cleared from the nasal cavity?

Cilia move mucus posteriorly to be swallowed

Which three cranial nerves provide innervation to the nasal cavities?

Olfactory [I], Trigeminal [V], Facial [VII]

Which cranial nerve is responsible for olfaction in the nasal cavity?

Olfactory nerve [I]

Which cranial nerve provides general sensation to the nasal cavity?

Trigeminal nerve [V]

Which branch of trigeminal nerve supplies the anterior region of nasal cavity?

Ophthalmic nerve [V1]

Which branch of trigeminal nerve supplies the posterior region of nasal cavity?

Maxillary nerve [V2]

Which cranial nerve provides parasympathetic innervation (secretomotor) to nasal glands?

Facial nerve [VII] via greater petrosal nerve

Where do parasympathetic fibers of the nasal cavity synapse?

In the pterygopalatine ganglion

What is the spinal cord origin of sympathetic fibers to the nasal cavity?

T1 spinal cord level

Where do sympathetic fibers to the nasal cavity synapse?

Superior cervical sympathetic ganglion

By which routes do postganglionic sympathetic fibers reach the nasal cavity?

Along blood vessels or by joining maxillary nerve [V2] in the pterygopalatine fossa

Which arteries supply the nasal cavity?

Terminal branches of maxillary & facial arteries, and ethmoidal branches of ophthalmic artery

Which major artery gives rise to maxillary and facial arteries?

External carotid artery

Which major artery gives rise to ethmoidal branches?

Internal carotid artery

What type of bones contribute to the nasal skeletal framework?

Unpaired and paired bones

Which unpaired bones form part of the nasal framework?

Ethmoid, sphenoid, frontal, vomer

Which paired bones form part of the nasal framework?

Nasal, maxillary, palatine, lacrimal, and inferior conchae

What is the key bone of the nasal skeletal framework?

Ethmoid bone

What is the general nature of the ethmoid bone?

Single, complex cuboidal bone

Which walls of the nasal cavity does the ethmoid bone contribute to?

Medial wall, lateral wall, and roof

Which paranasal sinuses are contained within the ethmoid bone?

Ethmoidal cells (air cells)

What shape does the ethmoid bone have overall?

Cuboidal

What are the rectangular box-like structures in the ethmoid bone called?

Ethmoidal labyrinths

How many ethmoidal labyrinths are there?

Two, one on each side

What are ethmoidal labyrinths made of?

Two delicate sheets of bone sandwiching ethmoidal cells

What is the lateral sheet of the ethmoidal labyrinth called?

Orbital plate

What does the orbital plate form?

Part of the medial wall of the orbit

What does the medial sheet of the ethmoidal labyrinth form?

Upper part of the lateral wall of the nasal cavity

What shelves project from the medial sheet of ethmoid?

Superior and middle conchae

What direction do the superior and middle conchae curve?

Downward, with free medial margins

What structure forms a prominent bulge inferior to the middle concha origin?

Ethmoidal bulla

What causes the ethmoidal bulla?

Middle ethmoidal cells

What groove extends anterosuperiorly from under the ethmoidal bulla?

Ethmoidal infundibulum

What duct continues through the ethmoidal infundibulum into the frontal sinus?

Frontonasal duct

What perforated sheet unites the two ethmoidal labyrinths superiorly?

Cribriform plate

What is the location of the cribriform plate?

At the apex of the nasal cavities, filling the ethmoidal notch in the frontal bone

What does the cribriform plate separate?

Nasal cavity below from cranial cavity above

What passes through the perforations of the cribriform plate?

Olfactory nerve fibers [I]

What large triangular process rises from the superior surface of the cribriform plate?

Crista galli

What is the function of the crista galli?

Anchors the falx cerebri

What vertical sheet descends from the cribriform plate?

Perpendicular plate of the ethmoid

What is the shape of the perpendicular plate?

Quadrangular

What does the perpendicular plate form?

Upper part of the nasal septum

Which bone does the perpendicular plate articulate with posteriorly?

Sphenoid bone (sphenoidal crest)

Which bones does the perpendicular plate articulate with anteriorly?

Frontal bone (nasal spine) and nasal bones

What cartilage does the perpendicular plate articulate with inferiorly/anteriorly?

Septal cartilage

Which bone does the perpendicular plate articulate with posteriorly at its inferior end?

Vomer

What bone does the superior surface of the ethmoidal labyrinth articulate with?

Frontal bone

What bones does the anterior surface of the ethmoidal labyrinth articulate with?

Frontal process of maxilla and lacrimal bone

What bone does the inferior surface of the ethmoidal labyrinth articulate with?

Upper medial margin of the maxilla

What delicate projection extends from the anterior-inferior ethmoidal labyrinth?

Uncinate process

With which structure does the uncinate process articulate?

Inferior concha across the maxillary hiatus

What is the main function of the external nose?

Extends nasal cavities onto the face and positions nares downward

What is the overall shape of the external nose?

Pyramidal with the apex anterior

What structure is continuous with the upper angle of the external nose?

Forehead (between orbital openings)

What holds the anterior nasal cavities open?

Skeletal framework

Which bones form the bony part of the external nose?

Nasal bones, parts of maxillae, and frontal bones