HNS28 Nasal Cavity & Paranasal Sinuses Flashcards

1
Q

Structure of nose

A

Main components of nose:

  1. Nasal bones
  2. Frontal processes of Maxillary bone
  3. Nasal part of Frontal bone

Features:
1. Nasal bone (articulate with frontal bone at Nasion)

  1. Glabella (flat surface on frontal bone between 2 orbits)
  2. Septal cartilage
  3. Alar cartilage
  4. Alar fibrofatty tissue
  5. Anterior nasal spine (attachment of septal cartilage inferior end)

Difference in appearances of nose —> due to difference in nasal cartilages

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2
Q

Nasal septum

A
  1. Ethmoid (Perpendicular plate)
  2. Septal cartilage
    - mobile structure
  3. 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

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3
Q

Nasal openings

A
  1. Anterior nasal aperture / Nares

2. Posterior nasal aperture / Choanae

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4
Q

***3 main cavities in face

A
  1. 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
  2. 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
  3. Oral cavity
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5
Q

Nasal concha

A
  1. Superior concha (ethmoid bone)
  2. Middle concha (ethmoid bone)
  3. Inferior concha (standalone bone)
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6
Q

***Blood supply of nasal cavity

A
  1. **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
  2. ***Facial artery (ECA)
    - Superior labial
    - Lateral nasal
  3. ***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:

  1. Pterygoid plexus
  2. Facial vein
  3. Ophthalmic vein
  4. Infraorbital vein

Kiesselbach area: Anteriorly 1/3 of nose —> highly vascularised —> prone to nose bleeding (Epistaxis) —> caused by trauma, infection, hypertension

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7
Q

***Nerve supply of nasal cavity

A

Special sense (smell)

  1. 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

  1. 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
  1. 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
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8
Q

Paranasal sinuses

A
  1. Frontal sinuses (within frontal bone)
  2. Maxillary sinuses (within maxillary bone)
  3. Ethmoidal sinuses (within ethmoidal bone)
  4. Sphenoidal sinuses (within sphenoidal bone)

Function:
- Resonance of voice

Blood supply:

  1. Maxillary artery (ECA)
  2. Ophthalmic artery (ICA)

Nerve supply:
- CN5
—> CNV2 (Maxillary)
—> CNV1 (Ophthalmic)

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9
Q

Le Fort classification of fracture of Maxilla

A

Type I
- across lower end of maxillary bone

Type II
- across maxillary bone, extend upward across orbits

Type III
- across 2 orbits

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10
Q

***Paranasal sinus drainage

A
  1. Frontal sinus
    - via Frontonasal duct —> Infundibulum —> ***Hiatus semilunaris (canal-shaped structure within Middle meatus)
  2. Maxillary sinus
    - via opening (posterior of Hiatus semilunaris) —> ***Hiatus semilunaris
    - Ostium of maxillary sinus —> high opening —> retain mucus —> most commonly infected sinus
  3. Sphenoid sinus
    - via opening into ***Sphenoethmoidal recess (above Superior meatus)
  4. 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
  5. Tears of eye:
    - drain via **Nasolacrimal duct (in Inferior meatus) —> **Inferior meatus
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11
Q

***Infratemporal fossa

A

Communicates with Pterygopalatine fossa through Pterygomaxillary fissure

Clinical significance:

  1. Communicate with other cavities
    - anterior: Inferior orbital fissure —> **Orbit
    - roof: Foramen rotundum, Pterygoid canal —> **
    Middle cranial fossa (brain)
    - medial: Sphenopalatine foramen —> ***Nasal cavity
  2. 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

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12
Q

***Pterygopalatine fossa

A
  • 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)

  1. Maxillary artery (3rd part) + its branches + Accompanying veins (drain into pterygoid plexus)
  2. ***Pterygopalatine ganglion (inferior)
  3. Sphenopalatine foramen (superior, opening to Sphenopalatine artery)
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13
Q

***Pterygopalatine ganglion and its branches

A
  • Within Pterygopalatine fossa —> Medial to infratemporal fossa
  • Secretory motor to lacrimal, nasal glands
  • ***Parasympathetic ganglion

Branches:

Nasal cavity region:

  1. Nasal branch (upper)
    - supply structures of nasal cavity
  2. Nasopalatine nerve (passes through Incisive foramen / canal)
  3. Greater palatine nerve (anterior hard palate)
    - supply palate, tonsil, nasal cavity
  4. Lesser palatine nerve (posterior hard palate)
    - supply palate, tonsil, nasal cavity
  5. Pharyngeal branch (most posterior hard palate)
    - supply roof of nasopharynx

Other regions:

  1. Ganglionic branch (pterygopalatine nerve)
    - communicates with Maxillary nerve (superior)
  2. 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)
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14
Q

***Sympathetic + Parasympathetic + Sensory component of Pterygopalatine ganglion

A

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
—>

  1. Parasympathetic input widely distributed to ALL branches in nasal cavity region
  2. 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

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15
Q

Upper vs Lower respiratory tract

A

Upper respiratory tract:
Nasal cavity

Lower respiratory tract:
Larynx or below

Separation of upper / lower respiratory tract:
Pharynx

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16
Q

Inflammation of nasal cavity

A

Rhinitis

Causes:
1. Infection
- can spread to:
—> Anterior cranial fossa
—> Middle ear through auditory tube
—> Paranasal sinuses
—> Lacrimal apparatus and conjunctiva
  1. Allergy