TBL26 - Nose and Nasal Cavity

Question 1

What does the septal nasal cartilage divide the nose into? Skin covering the cartilaginous skeleton extends into where and is continuous with what posteriorly? In the nasal cavity, what contributes to formation of the nasal septum and what does this septum separate?

Answer 1

1) The septal nasal cartilage divides the nose into right and left halves
2) Skin covering the cartilaginous skeleton extends into the nose, which is continuous posteriorly with the nasal cavity
3) In the nasal cavity, the septal nasal cartilage contributes to formation of the nasal septum that separates the right and left cavities

Question 2

What are the lateral walls of the nasal cavity formed from anterior to posterior by? What are two bony processes of the ethmoid bone? Is the inferior concha an independent bone?

Answer 2

1) The lateral walls of the nasal cavity are formed from anterior to posterior by the maxilla, ethmoid bone, and vertical plate of the palatine bone
2) The superior and middle conchae are bony processes of the ethmoid bone
3) The inferior concha is an independent bone

Question 3

What do the conchae hang like and from where in the nasal cavity? What underlies the respective superior, middle, and inferior conchae? What lies posterior to the superior concha?

Answer 3

1) The conchae hang like louvers (blinds) from the lateral walls of the nasal cavity
2) The superior, middle, and inferior nasal meatuses underlie the respective conchae
3) Posterior to the superior concha, observe the sphenoethmoidal recess

Question 4

What are the ethmoid bone and the middle concha hollowed out by? Locate the inferior concha. What is the inferior portion of the nasal septum attached to?

Answer 4

1) The ethmoid bone and the middle concha are hollowed out by ethmoidal air cells
2) The inferior portion of the nasal septum is attached to the hard palate

Question 5

What is the anterior portion of the nasal septum formed by? Posteriorly, what is the septum formed by?

Answer 5

1) The anterior portion of the nasal septum is formed by the septal cartilage
2) Posteriorly, the septum is formed by the perpendicular plate of the ethmoid bone and the vomer bone

Question 6

What lines the nasal cavity and nasal septum? What moves filtrates from inspired air toward the pharynx?

Answer 6

1) Respiratory mucosa lines the nasal cavity and nasal septum
2) Mucociliary flow moves filtrates from inspired air toward the pharynx

Question 7

What are paranasal sinuses? What do ostia in the lateral walls of the nasal cavity permit? How much mucus do the mucosae of the nasal cavity and paranasal sinuses produce per day? What drains the sinuses into the nasal cavity?

Answer 7

1) Paranasal sinuses are air-filled cavities in cranial bones associated with the nasal cavity
2) Ostia in the lateral walls of the nasal cavity permit invaginations of the nasal mucosa to enter and line the paranasal sinuses
3) Mucosae of the nasal cavity and paranasal sinuses produce 750 ml mucus/day
4) Mucociliary flow drains the sinuses into the nasal cavity

Question 8

What subdivides the ethmoidal sinus? How many chambers do the frontal, sphenoidal, and maxillary sinuses contain? What do the sinuses do in relation to maintaining the head in the upright position?

Answer 8

1) Ethmoidal cells subdivide the ethmoidal sinus
2) The frontal, sphenoidal, and maxillary sinuses are single-chambered
3) The sinuses reduce the muscular workload required to maintain the head in the upright position

Question 9

Where do the frontal sinus, maxillary sinus, and anterior and middle ethmoidal cells drain into? Where do the posterior ethmoidal cells and sphenoidal sinus drain into? (Where is the sphenoethmoidal recess?)

Answer 9

1) The frontal sinus, maxillary sinus, and anterior and middle ethmoidal cells drain into the middle meatus
2) The posterior ethmoidal cells drain into the superior meatus
3) The sphenoidal sinus drains into the sphenoethmoidal recess

Question 10

How can severe infections of the ethmoidal cells cause blindness?

Answer 10

1) If nasal drainage is blocked, infections of the ethmoidal cells may break through the fragile medial wall of the orbit
2) Severe infections from this source may cause blindness because some posterior ethmoidal cells lie close to the optic canal, which gives passage to the optic nerve and ophthalmic artery

Question 11

Why do sinus infections most commonly occur in the maxillary sinuses and how are they cannulated for draining?

Answer 11

1) The maxillary sinuses are the most commonly infected, probably because their ostia (openings) are commonly small and are located high on their superomedial walls
2) When the mucous membrane of the sinus is congested, the maxillary ostia are often obstructed
3) Because of the high location of the ostia, when the head is erect it is impossible for the sinuses to drain until they are full
4) Because the ostia of the right and left sinuses lie on the medial sides (i.e., are directed toward each other), when lying on one’s side only the upper sinus (e.g., the right sinus if lying on the left side) drains. A cold or allergy involving both sinuses can result in nights of rolling from side to side in an attempt to keep the sinuses drained
5) A maxillary sinus can be cannulated and drained by passing a cannula from the naris through the maxillary ostium into the sinus

Question 12

Where does the maxillary artery reside in? What is the terminal branch of the maxillary artery? After reaching the nasal cavity, what supplies the nasal mucosa?

Answer 12

1) The maxillary artery resides in the infratemporal fossa
2) The sphenopalatine artery is its terminal branch
3) After reaching the nasal cavity, the sphenopalatine artery supplies the nasal mucosa

Question 13

In the anterior nasal septum, what is the Kiesselbach area?

Answer 13

In the anterior nasal septum, the Kiesselbach area is an anastomotic site for branches of the sphenopalatine artery with multiple arteries (ignore their names)

Question 14

Why is epistaxis relatively common?

Answer 14

1) Epistaxis (nosebleed) is relatively common because of the rich blood supply to the nasal mucosa
2) In most cases, the cause is trauma and the bleeding is from an area in the anterior third of the nose (Kiesselbach area)

Question 15

What nerves supply the mucosae of the nasal septum and lateral walls of the nasal cavity?

Answer 15

Sensory branches (assessed below) from CN V1 and CN V2 supply the mucosae of the nasal septum and lateral walls of the nasal cavity

Question 16

Where does olfactory mucosa reside and what is this structure formed by?

Answer 16

Olfactory mucosa resides on the roof of the nasal cavity, which is formed by the cribriform plate of the ethmoid bone, the superior aspect of the nasal septum, and the superior nasal conchae

Question 17

What type of neurons are olfactory cells? What are their dendritic cilia activated by? What do axons of the bipolar neurons traverse and synapse with?

Answer 17

1) Olfactory cells are bipolar neurons
2) Their dendritic cilia are activated by odoriferous substances
3) Axons of the bipolar neurons traverse tiny foramina in the cribriform plate of the ethmoid bone and synapse with sensory neurons whose central axons form olfactory tracts of the olfactory nerve (CN I) that terminate in the brain

Question 18

How can anosmia serve as a clue to fracture of the cranial base and rhinorrhea?

Answer 18

1) In severe head injuries, the olfactory bulbs may be torn away from the olfactory nerves, or some olfactory nerve fibers may be torn as they pass through a fractured cribriform plate
2) If all the nerve bundles on one side are torn, a complete loss of smell will occur on that side; consequently, anosmia may be a clue to a fracture of the cranial base and cerebrospinal fluid rhinorrhea (leakage of the fluid through the nose)