The Nose & Paranasal Sinuses Flashcards
Describe the external nose
- Made up of two parts:
- Nasal bones
- Nasal (alar) cartilages
- Naris = external nasal aperture
NB: hairy skin extends into the nasal cavity a short distance - this is the vestibule of the nose
Describe the nasal bones
- Superiorly: meet in the midline
- There is an opening inferior to the bones (between the maxillae)
- Maxillae meet inferiorly to form the lower boundary of the opening
Describe the nasal cartilages
- Hyaline cartilage
- Attach to the edge of the nasal opening
- Major alar cartilages form lateral boundary of the naris anteriorly
- Fibrofatty tissue forms it posteriorly
- Form anterior septum
What forms the medial walls of the nasal cavity?
- Nasal septum - divides cavity in two formed by:
- Perpendicular plate of the ethmoid superiorly
- Cartilage anteriorly
- Vomer posteriorly
Little’s area = highly vascularised area in anterior nasal septum, inflammation causes epistaxis (nosebleeds)
Describe the roof of the nasal cavity
- The roof is arched, formed from:
- Nasal bones anteriorly
- Cribriform plate in the middle
- Inferior surface of sphenoid (body) posteriorly
What forms the floor of the nasal cavity?
- Palatine processes of the maxillae anteriorly
- Horizontal plate of the palatine bones posteriorly
(i.e. the hard palate)
What forms the lateral walls of the nasal cavity?
Maxilla & three concha
Discuss the nasal conchae
- Large, medially-directed bony elements
- Covered in highly vascular mucous membranes
- Warm & humidify air as it’s drawn past
- Shelf-like, beneath each is a meatus
NB: superior/middle are part of ethmoid, inferior is a separate bone
Where does the sphenoid sinus open into the nasal cavity?
Sphenoethmoidal recess
What opens into the superior meatus?
Posterior ethmoidal air cells
What opens into the middle meatus?
- Anterior & middle ethmoidal air cells
- Frontal sinus
- Maxillary sinus
What opens into the inferior meatus?
Nasolacrimal duct
Discuss the blood supply to the nasal cavity
Three sources:
- Sphenopalatine branch of the maxillary artery (predominant)
- Anterior ethmoidal branch of ophthalmic artery
- Labial branch of the facial artery
Venous drainage of the nasal cavity
Veins follow artery to drain to:
- Facial vein
- Ophthalmic vein
- Sphenopalatine vein - part of pterygoid plexus
Discuss the mucous membrane of the nasal cavity
- Olfactory part: roof and adjacent part of walls
- Vestibule: stratified squamous
- Rest: respiratory epithelium
Discuss the nerve supply to the nasal cavity
- Olfactory n. from olfactory mucous membrane
- Pass through cribriform plate
- General sensation: branches of Va & Vb
- Accompany vasculature
- Parasymp secretomotor: from PPG
- Pregang to PPG by greater petrosal n. (VII)
Describe the paranasal sinuses
- Series of membrane-lined cavities of facial bones
- Ciliated mucous columnar epithelium
- Currents directly spirally → openings
- For resonance (speech) & lighten the bones
Describe the frontal sinus
Lies about the orbit, can be quite extensive
Describe the maxillary sinus
- Large: occupies most of the maxilla
- Lies lateral to nasal cavity
NB: opening above floor of sinus
Describe the ethmoidal air sinuses
- Small, interconnected air cells between nose & orbit
- Middle sinus in the bulla of the ethmoid
- Hiatus semilunaris curved opening beneath bulla
- Openings of frontal, maxillary & anterior ethmoidal
Describe the sphenoidal sinus
- Opens in triangular space above superior concha
- Important relations:
- Pituitary fossa superiorly
- Cavernous sinus laterally
Discuss anterior cranial fossa fracture
- Can cause CSF rhinorrhoea - drainage via nose
- Leading to: purulent meningitis & anosmia
Discuss sinusitis
- Inflammation of paranasal sinuses
- Symptoms:
- Headache
- Feeling of pressure in eyes, nose, cheeks
- Cough
- Fever
- Halitosis
- Nasal congestions with thick mucous
Discuss maxillary sinusitis
- Causes pain/pressure in maxillary area
- May present with toothache
NB: Infection & damage more likely due to position of opening (drainage more difficult)
Discuss the relevance of the location of the sphenoid sinus
- Transphenoidal hypophysectomy
- Remove pituitary tumours confined to sella turcica/only extend to suprasellar region
- Endoscope inserted through nose to sinus
- Procedure of choice operation: significant advantages over open craniotomy
