L9: Nasal cavity Flashcards
Nasal cavities (3)
Nasal vestibule: small dilated space and lined w skin and contains hair
Respiratory region: largest part, rich neurovascular supply, lined by respiratory epithelium (ciliated and mucus cells)
Olfactory: small part at apex of cavity, lined by olfactory epithelium and contains olfactory receptors
General parts of external nose and relevance
Bony part and cartilaginous part
Cartilaginous part operated on by plastic surgeons
Cartilage form growth plates of nose - if damaged as a baby, nose may not grow as it should
Septal cartilage - trauma to cartilage can cause bleed within, cutting off blood supply to the cartilage –> loss of part of nose (nasal septal hematoma)
Floor
Same as roof of oral cavity
Consists of: palatine process of maxilla and horizontal plate of palatine
(maxilla and palatine bones form nasal crest which articulates w nasal septum)
Roof
Important in fracture - Nasal bone (most commonly fractured) - Frontal bone w nasal spine - Cribriform plate (ethmoid bone) - Sphenoid bone
Ethmoid bone
Formed by: - Cribriform plate - Crista galli - Perpendicular plate - L and R ethmoidal labyrinth - Orbital plate - Superior and middle conchae - Uncinate process - Infundibulum = communication between sinuses and nasal cavity
Medial wall
= nasal septum - Septal nasal cartilage anteriorly - Posteriorly mainly vomer and perpendicular plate of ethmoid bone - Small contributions by nasal bones where they meet at midline and nasal spine of frontal bone - Nasal crests of maxillary and palatine bone
Can get nasal septal hematoma
Lateral wall
- Ethmoid bone (sup and middle conchae) - Inferior concha (separate bony structure) - Nasal bone - Frontal bone - Perpendicular plate of palatine bone - Lateral process of septal cartilage - Major and minor ala cartilage - Medial pterygoid plate of sphenoid bone - Lacrimal bone (impt in drainage)
Sinuses drain into lateral wall
Where do sphenoidal sinuses drain?
Drain along top of nasal cavity
(Sits just under pituitary so e.g. pituitary tumour can be accessed via this sinus)
Drains into spheno-ethmoidal recess
Where do posterior ethmoidal air cells drain to?
Opening into lateral wall of superior meat (just deep to superior concha)
Which sinuses drain to lateral wall of middle meatus?
Frontal sinus, anterior and middle ethmoidal air cells, maxillary sinuses
Where does nasolacrimal duct drain to?
Opens just deep to inferior concha
Innervation of sinuses
Innervated by branches of trigeminal n [V]
Frontal sinus: V1
Maxillary: V2
Ethmoidal cells: V1 and V2
Sphenoid: V1 and V2
8 bones of nasal cavity
Unpaired: Ethmoid Sphenoid Frontal Vomer
Paired: Nasal Maxillary Palatine Lacrimal Inferior concha
What enters and exit via cribriform plate?
- [I] fibres
- Ant ethmoidal n of [V1] and
accompanying vessels - Nasal veins connecting to
superior sagittal sinus
What enters and exits via sphenopalatine foramen?
- Sphenopalatine branch of
maxillary a - Nasopalatine branch of [V2]
- Sup nasal branches of [V1]
What enters and exits via incisive canal?
- Nasopalatine n
- Terminal part of greater
palatine a
Small foramina in lateral wall
- A branch of infraorbital n [V2]
- A branch of greater palatine
n [V2]
Lymph drainage
Runs w veins rather than arteries, drains to submandibular, deep cervical and retropharyngeal nodes
Venous drainage
- Nasal v in foramen cecum
- Drainage to cavernous sinus
in nasal cavity - Drainage to pterygoid plexus
in infratemportal fossa
Drainage to facial v
Common site of anterior epistaxis
Littles area - area of signficant anastomoses = prone to nosebleeds
- Main artery: sphenopalatine a (end of maxillary a passing through sphenopalatine foramen)
- Septal branch of superior labial
- Ascending branch of greater palatine
- Septal branches of anterior and posterior ethmoidal a
Anastomosis over lower anterior part of septum (Littles area) and form Kieselbach’s plexus
Posterior epistaxis
Most commonly sphenopalatine a
Innervation
[I], [V1], [V2]
parasymp [VII]
sympa [T1]
