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