Nasal Cavities

Which bone forms the roof of the nasal cavity, and what passes through it?

Cribriform plate of the ethmoid; olfactory nerves (CN I)

Which bones form the floor of the nasal cavity?

Palatine process of the maxilla and horizontal plate of the palatine bone (the hard palate)

Which part of the septum is formed by the perpendicular plate of the ethmoid?

The superior/anterior bony part

Which part of the septum is formed by the vomer?

The posterior-inferior bony part

Which part of the septum is formed by septal cartilage?

The anterior (flexible) part

Mnemonic for the nasal septum

Perpendicular plate + Vomer + Cartilage (+ small maxillary and palatine crests along the floor)

Which nasal concha is a separate bone, not part of the ethmoid?

Inferior nasal concha

Causes of a deviated septum

Congenital or nasal trauma

Why can a deviated septum cause sinus infections?

It can block sinus drainage

Why do the turbinates increase surface area?

To warm, humidify, and filter inspired air

What forms the ethmoid bulla?

Middle ethmoidal air cells

What opens into the semilunar hiatus?

The frontonasal duct (anteriorly), anterior ethmoidal cells, and the maxillary ostium (posteriorly)

What is the osteomeatal complex, and why does it matter?

The semilunar hiatus/ethmoidal infundibulum region; a blockage here can cause multi-sinus infection

Where does the auditory (pharyngotympanic) tube open?

Lateral wall of the nasopharynx

How do upper respiratory infections reach the middle ear?

Through the auditory tube, causing otitis media

How can enlarged adenoids affect the ear?

They can block the opening of the auditory tube

General sensation to the anterior/superior septum

Medial internal nasal n. (from the anterior ethmoidal n., V1)

General sensation to the anterior/superior lateral wall

Lateral internal nasal n. (from the anterior ethmoidal n., V1)

General sensation to the posterior/inferior septum

Nasopalatine n. (V2)

Function of the parasympathetic fibers to the nasal mucosa

Mucous secretion

Function of the sympathetic fibers to the nasal mucosa

Vasoconstriction

Only preganglionic parasympathetics (greater petrosal) synapse; sympathetic (already postganglionic) and V2 sensory fibers pass through

Which fibers synapse in the pterygopalatine ganglion, and which pass through?

Sphenopalatine foramen

Through what opening do PPG branches enter the nasal cavity?

What can a cribriform plate fracture cause?

Anosmia (torn olfactory filaments) and possibly CSF rhinorrhea

Besides fractures, what else impairs smell?

Inflammation of the nasal mucosa (lateral wall or septum)

Which artery supplies most of the nasal cavity?

Sphenopalatine artery (terminal branch of the maxillary a., from the external carotid)

3 overall arterial sources of the nasal cavity

Sphenopalatine a. (maxillary, ECA), ethmoidal aa. (ophthalmic, ICA), and facial a. (ECA)

4 arteries that anastomose at Kiesselbach's area

Sphenopalatine, anterior ethmoidal, septal branch of the superior labial (facial), and greater palatine

Purpose of Kiesselbach's dense vascular plexus

Cartilage health and warming inhaled air

Anterior epistaxis: source, frequency, treatment

Kiesselbach's area; most common; usually controlled with external pressure

Posterior epistaxis: frequency and treatment

Less common, more blood, harder to stop; usually needs packing

Where does blood from a posterior nosebleed go?

Down the throat (nasopharynx -> oropharynx -> laryngopharynx), where it's swallowed or aspirated

2 functions of the paranasal sinuses

Lighten the skull and provide voice/sound resonance

Memory aid for what drains into the middle meatus

FAMM: Frontal, Anterior ethmoid, Middle ethmoid, Maxillary

Drainage map: superior meatus, sphenoethmoidal recess, inferior meatus

Superior meatus: posterior ethmoidal cells; sphenoethmoidal recess: sphenoid sinus; inferior meatus: nasolacrimal duct

Why does the maxillary sinus drain poorly?

Its ostium is high on the medial wall, so gravity doesn't help

Which sinuses does V1 supply?

Frontal sinus and ethmoid air cells (via anterior and posterior ethmoidal nn.)

Which sinuses does V2 supply?

Maxillary sinus (superior alveolar nn., infraorbital n.) and sphenoid sinus

What is sinusitis, and what causes it?

Inflammation of the sinus mucosa; caused by unresolved rhinitis (colds, allergies) or obstruction (polyps, deviated septum)

Why can maxillary sinusitis mimic a maxillary toothache?

The maxillary sinus and maxillary teeth share V2 innervation (superior alveolar nerves), so pain is referred

Where is frontal or ethmoid sinus pain felt?

Forehead and orbit region (V1)

What is the transsphenoidal approach?

A route through the nasal cavity and sphenoid sinus to reach the pituitary (sella turcica), usually to remove pituitary adenomas

• Beginning of the airway

• Smell

• Filtration

• Humidification and warming inspired air

• Decreasing weight of skull (sinuses)

Function of the Nose, Nasal Cavity and Sinuses:

Nasal bones

Identify the structure at #1

Anterior nasal spine

Identify the structure at #2

Nasal aperture

Identify the structure at #3

Fibroareolar tissue

Identify the structure:

Lateral

Identify the type of cartilage at #1

Alar

Identify the type of cartilage at #2

Septal

Identify the type of cartilage at #3

Vibrissae

Identify the structure:

Root of nose

Identify the structure at #1

Dorsum of nose

Identify the structure at #2

Apex of nose

Identify the structure at #3

Naris (nostril) of nose

Identify the structure at #4

Nasal septum

Identify the structure at #5

Ala of nose (wing)

Identify the structure at #6

Open at nares

Anterior boundary of nasal cavity

Choanae open to nasopharynx

Posterior boundary of nasal cavity

Many bones with conchae

Lateral wall of nasal cavity

Hard palate

Floor of nasal cavity

roof of nasal cavity

separates nasal cavity from anterior cranial fossa

hard palate

separates nasal cavity from oral cavity

Superior, middle and inferior nasal conchae

Identify the structures

Choanae

Identify the structure

Meatus

Space below each concha is called a...

superior nasal turbinate

identify the structure:

middle nasal turbinate

identify the structure:

inferior nasal turbinate

identify the structure:

Middle meatus

Identify the structure at #1

Superior ethmoidal recess

Identify the structure at #2

Olfactory mucosa

Identify the structure at #1

superior ethmoidal recess

space above superior conchae

Turbinate

Concha lined with mucosa

The ethmoidal portion of the roof, where it is olfactory mucosa

Nasal cavity is lined with respiratory mucosa, except in...

middle turbinate

which turbinate is a part of the ethmoid bone?

nasal septum

divides nasal cavity into right and left nasal cavities

Bone and cartilage covered by mucosa

The nasal septum consists of...

Deviated septum

Identify the pathology in the image on the left:

Deviated septum

Identify the pathology:

Difficulty breathing, nose bleeds

If a deviated septum is severe, what can it cause?

• Air filled-spaces lined with respiratory mucosa

• Drain into nasal cavity

• Named for the bone they are in

What are paranasal sinuses?

superior turbinate

which turbinate is the smallest?

Middle concha (cut)

Identify the structure at #1

Semilunar hiatus

Identify the structure at #2

Middle meatus

Identify the structure at #3

Opening of lacrimal duct

Identify the structure at #4

Inferior meatus

Identify the structure at #5

Inferior concha (cut)

Identify the structure at #6

Superior concha (cut)

Identify the structure at #7

Superior meatus

Identify the structure at #8

Sphenoethmoidal recess

Identify the structure at #9

Ethmoid bulla

Identify the structure at #10

In sphenoid ostia

Where is the probe?

Frontal sinus

Identify the structure at #1

Ethmoid cells

Identify the structure at #2

Maxillary sinus

Identify the structure at #3

Sphenoid sinus

Identify the structure at #4

ethmoidal air cells (sinus)

what sinuses sit directly medially to the orbit?

maxillary sinus

what sinuses sit inferiorly to the orbit?