3.2 Anatomy of the nasal cavity & paranasal sinuses

Question 1

NASAL SEPTUM
The nasal septum is partly bony and cartilaginous and separates the chamber of the nose into the left and right nasal cavities (lined by respiratory epithelium):

Bony part (immobile)

• Perpendicular plate of ethmoid bone: Superior part (descends from ______________)
• Vomer (thin flat bone): ____________ part Cartilaginous part (mobile)
• Septal cartilage: ____________ part (articulates with bony part)

Answer 1

cribriform plate;

Posteroinferior ;

Anterior

Question 2

NASAL CAVITY
The nasal cavity opens into the nostrils anteriorly and nasopharynx posteriorly (via __):
• Divided into the vestibule, respiratory region and olfactory area
• Each division of the nasal cavity is lined by a different type of epithelium/mucosa and serves different functions

Vestibule

• Lining: Skin (with fine hair)
• Filters inspired air (surrounds anterior external openings) → traps dirt

Rest of nasal cavity (lined by nasal mucosa firmly bound to periosteum and perichondrium of supporting bones/cartilages)

Respiratory region (atrium) (inferior 2/3)

• Respiratory epithelium (______________ epithelium with goblet cells): Allows passage of air and secretion of mucus (helps to trap pathogens and particulate matter)
• Olfactory area (apex): Olfactory cells with olfactory receptors, involved in olfaction (___________ of olfactory cells unite to form the nerve bundles of CN I → pass through the ________________ → olfactory bulb of brain)

Answer 2

choanae;

pseudostratified ciliated columnar;

central processes;

foramina of cribriform plate

Question 3

NASAL CONCHAE (TURBINATES)

The nasal conchae are curved shells of bone which project from the lateral wall of the nasal cavity, allowing for airflow through the cavity:
• Functions: increases surface area of the nasal cavity and slows down airflow for humidification of air before it enters the nasopharynx
• Superior and middle conchae from the ethmoid; inferior conchae are individual bones
• 3 pairs of conchae (superior, middle, inferior) → _______________ is the longest and broadest (covered by mucous membrane containing large vascular spaces)
• Divides the nasal cavity into 4 air passages: inferior meatus, middle meatus, superior meatus, ____________________ (posterosuperior to superior concha)
• Some people have an additional supreme meatus (above superior concha)

The middle meatus contains an elevation (bulla ethmoidalis) which contains the anterior ethmoidal air cells which open near/on it:
• Middle ethmoidal air cells open ________________ to the bulla ethmoidalis
• __________________ (contains opening of the maxillary sinuses) is found below the bulla → continues laterally as the ethmoidal diverticulum (opening of frontal sinuses)

Answer 3

inferior concha;

sphenoethmoidal recess;

on/superior;

Hiatus semilunaris

Question 4

VASCULATURE OF NASAL CAVITY
The nasal cavity receives a rich blood supply from the ICA and ECA which varies the humidity and temperature of inspired air:

Supply Branches/Tributaries

• Arterial ICA branches: ___________________* (branch of ophthalmic artery; descends via the cribriform plate)
• ECA branches: _______________* (branch of maxillary artery), ___________* (branch of maxillary artery), ______________ (from facial artery), lateral nasal branches of facial artery
• Kiesselbach’s (Little’s) area: anastomoses of arteries (especially in the anterior third of the nose) → common site of epistaxis (nosebleeds) especially in children

Venous
Rich venous plexus deep to the nasal mucosa (largely follows arterial supply):
• Drains into the ___________________
• Significant in exchanging heat/warming air before it enters lungs

Answer 4

anterior and posterior ethmoidal arteries;

sphenopalatine artery;

greater palatine artery;

superior labial artery;

sphenopalatine, facial, ophthalmic veins

Question 5

Epistaxis: Epistaxis: often occur in the often occur in the _______________ due to the due to the rich blood supplyrich blood supply of the mucosaof the mucosa
• Commonly occur due to trauma, nose nose picking (other causes: hypertension, infection)
• Usually not severe and resolves after a while (prolonged epistaxis may indicate and resolves after a while (prolonged epistaxis may indicate haemostatic defects)→ epistaxis in elderly ocepistaxis in elderly occurs commonly due to hypertension

Danger area of the face: veins draining the nose communicate with the _________________ (in (in the infratemporal fossa) → communicates with the cavernous sinus (via emissary veins)
•Infections of the nose may spread to the cavernous sinus → dural venous sinus thrombosis (DVST) → compression of _______________passing through the sinus

Answer 5

Kiesselbach’s area;

pterygoid plexus;

CN III, IV, V, VI

Question 6

INNERVATION OF NASAL CAVITY

The nasal cavity receives special sensory (smell), general sensory, secretomotor innervation:

Special sensory (smell): Olfactory nerve (CN I)
Axons of olfactory receptors pass through the foramina in the \_\_\_\_\_\_\_\_\_\_\_ to the olfactory bulb:
• Olfactory bulb (part of brain) lies on the superior surface of the cribriform plate above the nasal cavity 

General sensory
- supplies the nasal septum and lateral walls: ______________, _______________
- Supplies the external skin (V1 and V2 branches): ______________
• Sneeze reflex is mediated by CN V2

Secremotor: Facial nerve (CN VII)
- Arises from the ______________ → ______________ → synapses in the pterygopalatine ganglion → joins the branches of _______________

Cribriform plate fractures: may occur due to nose trauma (damaging nasal
- Irreversible damage to olfactory bulb loss of smell (anosmia)
- Penetrates the meningeal linings of the brain → CSF leakage results in infection
(meningitis, encephalitis,

Answer 6

cribriform plate;

Nasopalatine nerve (CNV2), Nasociliary nerve (CNV1);

Trigeminal nerve

superior salivatory nucleus; greater petrosal nerve; maxillary nerve (CN V2)

Question 7

PARANASAL SINUSES
There are 4 paired paranasal sinuses (named according to the cranial bone in which they are located), which are air-filled extensions of the respiratory part of nasal cavity:
• Lined by respiratory mucosa (_______________ epithelium) → cilia beat towards the nasal cavity
• Present by birth (except frontal); develops further during childhood by the nasal cavity eroding into surrounding bone
• Continuous with the nasal cavity through various openings (outgrowths of nasal cavity) → secretions drain back into nasal cavity via openings in roof and lateral walls
• Sinuses drain fluids into the nose during infections/inflammations (e.g. colds, responses to allergens, polyps, nasal tumours)
• Functions: increases resonance of voice (think of putting a speaker in a cup), variation of temperature (increases/decreases blood supply → main function)

Sinusitis: inflammation of mucosa lining the paranasal sinuses due to spread of URTIs to the sinuses (accompanied by pain and
swelling )
- Tenderness/pain when pressure is applied to the face
- Common symptoms include thick nasal mucus , nasal
congestion , facial pain , fever, headaches, poor sense of smell, cough
- May occur due to obstruction of drainage –> most common in the ______________ as it is the most inferior air sinus (cilia needs to beat against gravity to drain secretions)

Answer 7

pseudostratified ciliated columnar;

maxillary sinus

Question 8

FRONTAL SINUSES
The frontal sinuses are the most superior paranasal sinuses found under the forehead and are triangular in shape → develops after 2 years of age:
• Drains into the nasal cavity via the __________ into the _______________ (at the ethmoidal diverticulum along the hiatus semilunaris)
• Innervation: _________________

Answer 8

frontonasal duct; middle meatus;

supraorbital nerves (CN V1)

Question 9

ETHMOIDAL SINUSES
The ethmoidal sinuses are found in the lateral part of the ethmoid bone (between the nasal cavity and orbit) → infections may spread to the orbit (only separated by thin bone):
• Possesses 13 – 18 cavities (ethmoidal cells) on each side
• Innervation: _______________

Cells Drainage

• Middle meatus: ___________________
• Superior meatus: _______________

Answer 9

anterior & posterior ethmoidal branches of nasociliary nerves (CN V1);

Anterior ethmoidal, Middle ethmoidal ;

Posterior ethmoidal

Question 10

SPHENOID SINUSES
The sphenoid sinuses are relatively superior at the level of sphenoethmoidal recess:
• Unevenly divided by the bony septum in the body of sphenoid (fragile sphenoid bone)
• Thin plates of bone separate these sinuses from the optic nerves and chiasm, pituitary gland/fossa, internal carotid arteries, cavernous sinuses
• Drains into the roof of the nasal cavity (sphenoethmoidal recess) → _______________
• Innervation: ___________________

Answer 10

superior meatus ;

posterior ethmoidal branch of nasociliary nerves (CN V1)

Question 11

MAXILLARY SINUSES
The maxillary sinuses are the largest paranasal sinuses and form the pyramidal cavities in the body of the maxillae:
• Drain via the semilunar hiatus into the middle meatus • Innervation: _________________ → mucous membrane of sinus has the same nerve supply as the maxillary teeth (sinusitis → toothache)

Relation
- Medial: ______________(underneath frontal sinus opening); Maxillary sinusitis (most commonly infected out of all sinuses) → fluid from frontal sinuses can drain into maxillary sinuses (route for infection)

• Superior: Bony orbit
• Inferior: Oral cavity, maxillary molar teeth
  • Fractures in maxilla: affects the sinuses (route for infection)
  • Fractures of root (during removal of maxillary molar teeth): not properly retrieved → driven superiorly into the maxillary sinus (provides passageway between the mouth and sinus for infection)

Answer 11

alveolar nerves (branches of CN V2);

Nasal cavities;