Nose Flashcards
What are the anatomical features of the external nose?
Dorsum (bridge of nose)
Ala (wing of nose)
Naris (nostril)
note: skin covering the nose extends into the vestibule of the nasal cavity (drawn down as FNP & nasal placodes descend) - defined by the limen nasil
Rest of nasal cavity covered with vibrissae (hairs) - mechanical impedance to particulates & muco-ciliary escalator
What are the different bony and cartilaginous components of the nose?
Bones:
- nasal bone
- frontal process of maxilla
- lacrimal bone + nasolacrimal groove
Cartilages:
- lateral process of septal cartilage
- superior margin of septal cartilage
- major alar cartilage
- minor alar cartilages
What are the different components of the nasal cavity?
Conchae/turbinates create 5 passages with in the cavity (one unpaired & 3 paired)
- superior concha
- middle concha
- inferior concha
- spheno-ethmoidal recess
Choanae = exit of nasal cavity into the nasopharynx
- superior meatus
- middle meatus
- inferior meatus
What are the different openings in the nasal cavity?
SINUSES:
- frontal sinus
- nasolacrimal duct
- infundibulum opening of frontonasal duct —> drains into frontal sinus & ant. ethmoidal cells
- opening of maxillary sinus in floor of spheno-ethmoidal recess
- pharyngeal opening of pharyngotympanic tube
- sphenoidal sinus
- ethmoidal sinuses: opening of middle ethmoidal cells onto bulla ethmoidalis & opening to pos. ethmoidal cells into lateral of superior meatus
FORAMINA:
- foramen cecum (cribiform plate) = nasal veins —> superior sagittal sinus (in some individuals)
- sphenopalatine foramen = sphenopalatine artery & maxillary nerve
- incisive canal (hard palate) = sphenopalatine nerve & greater palatine artery
What are the different components of the ethmoid bone?
Cribiform plate + foramina (passage of olfactory nerve fibres)
Crista galli = protrudes superior to cribiform plate
Perpendicular plate = vertical plate protruding inferior to cribiform plate
Uncinate processes (on palatine processes of maxillary bone)
Orbital plates (forms medial walls of orbital cavities)
Ethmoidal labyrinthes (in orbital plates)
Describe the arterial supply of the nasal cavities.
LATERAL:
- external carotid artery —> maxillary artery —> sphenopalatine artery & greater palatine artery
- internal carotid artery —> opthalmic artery —> ant. & pos. ethmoidal arteries
- lateral nasal branches of facial artery
MEDIAL:
- external carotid artery —> facial artery —> septal branch of superior labial artery
- branch of sphenopalatine artery
- greater palatine artery
- ant. & pos. ethmoidal arteries
- Kiesselbach’s plexus (most common site of anterior epistaxsis)
Describe the venous drainage of the nasal cavities.
Nasal vein (foramen cecum)
Drainage to:
- facial vein
- cavernous sinus
- pterygoid plexus
Describe the innervation of the nasal cavities.
- olfactory nerve (CNI) —> olfactory bulb —> ant. ethmoidal nerve
- maxillary nerve —> pterygopalatine ganglion —> pharyngeal nerve & CNV1 & CNV2
- internal nasal branches of infra-orbital nerve
- nasal branch of ant. superior alveolar nerve
- nasopalatine nerve
- greater & lesser palatine nerves
General sensory innervation:
- ANTERO-SUPERIOR = opthalmic nerve (CNV1) —> branches of nasociliary nerve
- POSTERO-INFERIOR = maxillary nerve (CNV2) —> nasopalatine nerve (septum) & greater palatine nerve (lateral walls)
Contrast the epithelium present in the nose.
Respiratory region = pseudostratified ciliated columnar cells + goblet cells
Olfactory region = non-motile cilia on olfactory cells + olfactory receptors (axons of terminal branch visible)
How can the nasal septum be damaged?
Nasal septum deviation (congenital or due to trauma) —> causes narrowing & obstruction
Nasal septum necrosis (caused by trauma —> poor blood supply to cartilage) —> saddle nose deformity
What are the paranasal sinuses, and what function do they serve?
Paired mucous membrane-lined out-pocketings of the nasal cavity
- may contribute to conditioning of inspired air (reservoir of humidified air to mix with inspired air)
- may reduce weight of the skull
- maxillary
- frontal
- ethmoidal
- sphenoid
What are the features of the maxillary sinus?
Boundaries:
- roof = floor of orbit
- floor = alveolar part of maxilla (contains roots of first 2 molars & superior alveolar nerve)
Contains pterygopalatine & infratemporal fossae (posteriorly)
Present at birth, enlarges from ~8yrs (therefore sinusitis is unusual in young children)
Opens into middle meatus
What are the features of the ethmoidal sinuses?
Ethmoidal air cells between orbit & nasal cavity
- anterior cells = drain into middle meatus via infundibulum
- middle cells = on bulla, drain into middle meatus
- posterior cells = drain into superior meatus
What are the features of the frontal sinus?
Not present at birth
Variable in size
Related to ant. cranial fossa & the orbit
Drains into the middle meatus via the frontonasal duct (through ethmoid bone)
What are the features of the sphenoidal sinuses?
Small at birth; enlarges after puberty
- superior to roof of nasopharynx
- inferior to pituitary fossa & middle cranial fossa
- also related to cavernous sinus, internal carotid artery, posterior cranial fossa, & pons
Give some examples of nose-related conditions.
Rhinitis =
- inflammation of nasal mucosa —> swelling & increased volume of secretions
- caused by infection (viral - “cold”), allergies, nasal polyps
Nasal polyps =
- ~2%-4% prevalence, possible link to chronic rhinosinusitis (due to infiltration of eosinophils & oedema)
- grow close to ostiomeatal complex of nasopharynx (ostium of duct draining meatus)
- causes nasal obstruction —> snorting/obstructive sleep apnoea
Sinusitis =
- inflammation of mucosal lining of sinuses —> marked thickening —> obstruction —> apnoea
- acute = 7-30 days, subacute = 4-12 weeks, chronic = >90 days
- bacterial infection (S. pneumoniae & H. influenzae) or viral secondary to bacterial infection (due to presence of oedema & mucus)
Epistaxis =
- bleeding from the nose (local or systemic)
- bimodal distribution: young (trauma/foreign bodies) & old (friable mucosa, warfarin)
- risks: alcohol (increased risk of trauma & coagulation defects), tumours, vascular abnormalities, mucosal drying, infections, granulomas, NSAIDs
Outline the management of epistaxis.
1.
- fluids to rehydrate
- Hippocratic method = pinch bridge of nose
- lean forwards
- ice on forehead (vasoconstriction)
- Cautery (silver nitrate/electrical)
- Anterior packing (if cause is Kiesselbach’s plexus)
- Posterior packing (if cause is sphenopalatine artery)
- Surgical ligation (of sphenopalatie/maxillary/external carotid artery) or radiological embolisation
Contrast anterior and posterior packing.
ANTERIOR:
- insert “nasal tampon” about 7.5cm and then inflate (pushes pack against turbinates of side walls)
- uncomfortable, therefore insert “short & sharp”
- does not cover post-nasal space very well, so some bleeding can still occur
- make sure pack isn’t hanging out
- place bolster on to catch further bleeding & to identify soaked pads
POSTERIOR:
- gauze padding packed into nose —> obstructs back of nose to prevent blood entering the nasopharynx
- balloon inflated in the pos. choana (inflate once balloon is seen in the oropharynx) in order to wedge packing in place
What are the functions of the nose?
General:
- olfaction
- respiration
- filter & humidify air
- drain & eliminate paranasal sinuses & nasolacrimal duct secretions
What is the cause of copious nasal discharge in nasal infections?
Inflammatory reactions —> increased leakage of interstitial fluid
Increased mucous secretions
Why does sinusitis cause headaches and facial pain?
Blocked nasal passages —> interrupted discharge of secretions from sinuses & irritation of mucosa
Why may a fractured cribiform plate of the ethmoid bone lead to a loss of smell and a runny nose?
Tearing of olfactory nerve filaments as they enter the floor of the anterior cranial fossa
—> anosmia & rhinorrhoea (?CSF)
Why can infection of the teeth spread to the maxillary sinus? Why can the maxillary sinus be difficult to drain?
Roots of maxillary premolar/molar teeth project into the floor of the maxillary sinus, so infection from the root may perforate the bone and affect the sinus
High location of ostium on the medial wall of maxilla becomes easily blocked during maxillary congestion —> slow drainage of pus
What are the bony boundaries of the maxillary air sinus?
SUPERIOR = floor of the orbit
MEDIAL = lateral margins of the nasal cavity
LATERAL = body of maxilla
INFERIOR = alveolar process of maxilla
What is the sensory nerve supply of the paranasal sinuses?
Ophthalmic & maxillary divisions of the trigeminal nerve
