HNS28 Nasal Cavity & Paranasal Sinuses Flashcards
Structure of nose
Main components of nose:
- Nasal bones
- Frontal processes of Maxillary bone
- Nasal part of Frontal bone
Features:
1. Nasal bone (articulate with frontal bone at Nasion)
- Glabella (flat surface on frontal bone between 2 orbits)
- Septal cartilage
- Alar cartilage
- Alar fibrofatty tissue
- Anterior nasal spine (attachment of septal cartilage inferior end)
Difference in appearances of nose —> due to difference in nasal cartilages
Nasal septum
- Ethmoid (Perpendicular plate)
- Septal cartilage
- mobile structure - Vomer
- articulate with ***hard palate (palatine process of maxilla + horizontal plate of palatine bone)
(4. Sphenoid bone (posterior nasal cavity)
- articulate with occipital bone posteriorly —> Clivus: Brainstem above)
Clinical significance:
Nasal septal deviation (from midline)
—> result of birth injury / congenital malformation / postnatal trauma
—> if severe can obstruct breathing
Nasal openings
- Anterior nasal aperture / Nares
2. Posterior nasal aperture / Choanae
***3 main cavities in face
- Nasal cavities:
- Roof (superior to ethmoidal sinus): Frontonasal + Ethmoidal + Sphenoidal bones
—> Anterior cranial fossa: Olfactory nerve (CN1)
—> pass through Cribriform plate of ethmoid bone
—> **Olfactory epithelium (contains cell bodies of CN1)
- Floor: Hard palate
- Lining: **Pseudostratified columnar epithelium
- Lateral wall: Superior concha + Superior meatus (space) + Middle concha + Middle meatus (space) + Inferior concha + Inferior meatus (space)
- Medial wall: Nasal septum: divide nasal cavity - Orbit:
- underneath: Infraorbital foramen (Infraorbital nerve / CNV2)
- 再underneath: Maxillary sinuses (Largest sinus)
- medial: Ethmoidal sinus (within ethmoid bone)
- ***Ethmoid bone (Cribriform plate): thin —> easily fractured by head trauma —> tear meninges —> CSF leakage —> drain into nasal cavity —> CSF Rhinorrhea - Oral cavity
Nasal concha
- Superior concha (ethmoid bone)
- Middle concha (ethmoid bone)
- Inferior concha (standalone bone)
***Blood supply of nasal cavity
-
**Maxillary artery (total 13 branches) (ECA (8 branches))
- **Sphenopalatine artery: supply nasal cavity extensively
—> passes Pterygomaxillary fissure —> goes into Sphenopalatine foramen
—> into nasal cavity to distribute its branches
- **Greater palatine: supply **hard palate - ***Facial artery (ECA)
- Superior labial
- Lateral nasal - ***Ophthalmic artery (ICA) (also supply eyeball, extraocular muscles, ethmoid sinuses)
- Anterior ethmoidal
- Posterior ethmoidal
—> go up to orbit then extend down into nasal cavity —> anastomoses with Facial artery
Blood drains into:
- Pterygoid plexus
- Facial vein
- Ophthalmic vein
- Infraorbital vein
Kiesselbach area: Anteriorly 1/3 of nose —> highly vascularised —> prone to nose bleeding (Epistaxis) —> caused by trauma, infection, hypertension
***Nerve supply of nasal cavity
Special sense (smell)
- Olfactory nerve (CN1)
- olfactory cells degenerate at about 1% per year in most elderly person —> Anosmia
- other causes: conditions affecting olfactory receptors, bulb / tract in intracranial region
General sense
- Trigeminal nerve (CN5)
- Ophthalmic division (CNV1) (small part)
- Maxillary division (CNV2) (majority)
Visceral motor 3. Parasympathetic - CN7 —> Superior salivatory nucleus —> ***Greater petrosal nerve —> ***Pterygopalatine ganglion —> Nasal cavity —> ***ACh, ***VIP (vasoactive intestinal polypeptide) as neurotransmitter —> Vasodilation, Sinusoidal engorgement, Glandular discharge —> Nasal congestion
- Sympathetic
- Superior cervical ganglion
—> sympathetic plexus around **internal carotid artery
—> **Deep petrosal nerve
—> **Pterygopalatine ganglion
—> Nasal cavity
—> innervates mainly arterioles + arteriovenous anastomoses
—> **NA, ***neuropeptide Y as neurotransmitter
—> Vasoconstriction + ↓ Secretion
—> ↓ Nasal congestion
Paranasal sinuses
- Frontal sinuses (within frontal bone)
- Maxillary sinuses (within maxillary bone)
- Ethmoidal sinuses (within ethmoidal bone)
- Sphenoidal sinuses (within sphenoidal bone)
Function:
- Resonance of voice
Blood supply:
- Maxillary artery (ECA)
- Ophthalmic artery (ICA)
Nerve supply:
- CN5
—> CNV2 (Maxillary)
—> CNV1 (Ophthalmic)
Le Fort classification of fracture of Maxilla
Type I
- across lower end of maxillary bone
Type II
- across maxillary bone, extend upward across orbits
Type III
- across 2 orbits
***Paranasal sinus drainage
- Frontal sinus
- via Frontonasal duct —> Infundibulum —> ***Hiatus semilunaris (canal-shaped structure within Middle meatus) - Maxillary sinus
- via opening (posterior of Hiatus semilunaris) —> ***Hiatus semilunaris
- Ostium of maxillary sinus —> high opening —> retain mucus —> most commonly infected sinus - Sphenoid sinus
- via opening into ***Sphenoethmoidal recess (above Superior meatus) - Ethmoid sinus (Anterior, Middle, Posterior)
- Anterior: via opening of anterior ethmoid cells (anterior of Hiatus semilunaris) —> **Hiatus semilunaris
- Middle: via opening of middle ethmoid cells (in Ethmoidal bulla) —> **Ethmoidal bulla
- Posterior: via opening of posterior ethmoid cells (in Superior meatus) —> ***Superior meatus - Tears of eye:
- drain via **Nasolacrimal duct (in Inferior meatus) —> **Inferior meatus
***Infratemporal fossa
Communicates with Pterygopalatine fossa through Pterygomaxillary fissure
Clinical significance:
- Communicate with other cavities
- anterior: Inferior orbital fissure —> **Orbit
- roof: Foramen rotundum, Pterygoid canal —> **Middle cranial fossa (brain)
- medial: Sphenopalatine foramen —> ***Nasal cavity - Important contents
- Mastication muscles
- **Maxillary artery branches
- **Pterygoid plexus (venous plexus within sphenoid structure)
—> found between medial and lateral pterygoid muscle
—> communicates with:
—> ***Cavernous sinus (dural venous sinus)
—> Ophthalmic veins (orbit)
—> Facial veins (anterior)
—> ALL no valves
***Pterygopalatine fossa
- Small space found below orbit
- Lateral: open to Infratemporal fossa
- Medial: Palatine bone
- Anterior: Maxilla
- Posterior: Pterygoid process of sphenoid bone
Contents:
1. ***CNV2 (Maxillary nerve)
—> Meningeal branches
—> Zygomatic branch
- ***Zygomaticotemporal nerve (supply skin of temple) —> parasympathetic fibres to Lacrimal gland (via Lacrimal nerve)
- Zygomaticofacial nerve (supply skin of cheek)
—> Ganglionic branches (pterygopalatine nerves by Moore)
- 2 short nerves that suspend pterygopalatine ganglion
- sensory fibres (passed through ganglion from nose, palate, pharynx) + parasympathetic fibres (to lacrimal gland)
—> Alveolar nerves
- supply gum, cheek, upper teeth, maxillary sinus
- anterior, middle, posterior branch
(—> Infraorbital nerve
- from Trigeminal ganglion —> Middle cranial fossa —> Foramen rotundum —> Inferior orbital fissure —> Infraorbital foramen —> Infraorbital nerve)
- Maxillary artery (3rd part) + its branches + Accompanying veins (drain into pterygoid plexus)
- ***Pterygopalatine ganglion (inferior)
- Sphenopalatine foramen (superior, opening to Sphenopalatine artery)
***Pterygopalatine ganglion and its branches
- Within Pterygopalatine fossa —> Medial to infratemporal fossa
- Secretory motor to lacrimal, nasal glands
- ***Parasympathetic ganglion
Branches:
Nasal cavity region:
- Nasal branch (upper)
- supply structures of nasal cavity - Nasopalatine nerve (passes through Incisive foramen / canal)
- Greater palatine nerve (anterior hard palate)
- supply palate, tonsil, nasal cavity - Lesser palatine nerve (posterior hard palate)
- supply palate, tonsil, nasal cavity - Pharyngeal branch (most posterior hard palate)
- supply roof of nasopharynx
Other regions:
- Ganglionic branch (pterygopalatine nerve)
- communicates with Maxillary nerve (superior) - Orbital branch / Infraorbital nerve (enter orbit through inferior orbital fissure) (Infraorbital nerve from Maxillary nerve (sensory nerve): originate from Trigeminal ganglion —> Middle cranial fossa —> Foramen rotundum —> Inferior orbital fissure —> Infraorbital foramen —> Infraorbital nerve)
***Sympathetic + Parasympathetic + Sensory component of Pterygopalatine ganglion
Sympathetic:
***Deep petrosal nerve (sympathetic fibres from T1, T2)
—> Nerve to pterygoid canal (combine with greater petrosal nerve)
—> Pterygopalatine ganglion
—> Sympathetic input widely distributed to ALL branches in nasal cavity region
Parasympathetic:
**Greater petrosal nerve (from CN7 from middle ear)
—> **Foramen lacerum
—> Nerve to pterygoid canal (combine with deep petrosal nerve)
—> through Pterygoid canal
—>
- Parasympathetic input widely distributed to ALL branches in nasal cavity region
- Send Parasympathetic fibres upwards —> connects with **Zygomaticotemporal nerve (CNV2) —> connects with **Lacrimal nerve (CNV1) through communicating branch —> Lacrimal gland
Special Sensory:
1. Greater petrosal nerve (Special visceral sensory taste fibres) —> **Greater palatine nerve + **Lesser palatine nerve —> sense of taste of hard palate in nasal cavity region
General Sensory:
1. ***CNV2
Summary:
Pterygopalatine ganglion
General Sensory: from Maxillary nerve CNV2
Special Sensory: from Greater petrosal nerve from CN7 (from middle ear)
Parasympathetic: from Greater petrosal nerve from CN7 (from middle ear)
Sympathetic: from Deep petrosal nerve
Upper vs Lower respiratory tract
Upper respiratory tract:
Nasal cavity
Lower respiratory tract:
Larynx or below
Separation of upper / lower respiratory tract:
Pharynx
