Lecture 6: Nasal Cavity and Pterygopalatine Fossa

Nasal Cavity Development

Nasal pit without communication to oral cavity

Barrier between nasal and oral cavities breaks down

Nasal and oral cavities continuous, olfactory system develops, palate forming

Nasal and oral cavities separated by palate, olfactory system established, conchae developing, sinuses initiate later (term)

Nose Cartilage

CARTILAGE (hyaline)

Septal cartilage with broad lateral processes

Nares bounded by the U-shaped alar cartilage

Alar fibrofatty tissue

Infundibulum is opening of frontal sinus; concern for frontal sinus infection

Infundibulum is opening of frontal sinus; concern for frontal sinus infection

Nasal mucosa

Bound tightly to periosteum: Mucoperiosteum

Parasympathetic visceral motor (VE) of mucus glands: CN VII via pterygopalatine ganglion

Extends into the paranasal air sinuses

Aids in olfaction, humidification, cleansing, thermoregulation

Swells/shrinks to control caliber of nasal cavity (activity related)

Swells rapidly with rhinitis (infection), can prevent sinus

drainage or spread to sinuses

Rhinorrhea

Discharge from mucous membrane: “runny nose”

Rhinitis

Inflammation of nasal mucosa, may spread to:

1. Anterior cranial fossa via cribriform plate

2. Nasopharynx/retropharyngeal soft tissues via choanae

3. Middle ear via pharyngotympanic (eustachian) tube

4. Paranasal sinuses via openings

5. Lacrimal apparatus/conjunctiva via nasolacrimal duct

CSF Rhinorrhea

CSF discharge through nose

Fracture of cribriform plate

May result in Meningitis

Serious injury

Paranasal Air Sinuses

Grow from nasal cavity

Continuous mucosa

Lighten skull

Add resonance to voice

Born with small ethmoidal, rudimentary maxillary, sphenoidal sinuses

Sinusitis

Maxillary sinusitis-most common:

Maxillary sinus is difficult to drain

Teeth and sinus share sensory innervation

Ethmoid/sphenoid sinusitis:

Proximity to optic nerve (CN II) can put pressure on optic nerve or lead to optic neuritis

Transillumination of sinuses

Healthy is warm, red glow

Lack of glow—congestion/infection likely

Blow out fracture and the maxillary sinus

Inability to look up due to entrapped inferior rectus muscle

Mechanical concern

Pterygopalatine fossa

Between the neurocraniun and viscerocranium

Distribution hub for maxillary artery and maxillary nerve branches

All are branches of the Maxillary nerve (CN V2)

Somatic sensory (SA) branches of Maxillary nerve (CN V2) to NASAL CAVITY via Sphenopalatine foramen

Nasopalatine nerve: To nasal septum, anterior hard palate (via incisive canal)

Posterior lateral nasal branches: To lateral nasal wall

Somatic sensory (SA) branches of Maxillary nerve (CN V2) to PALATE via Lesser and Greater palatine foramina

Lesser and Greater palatine nerves

Hard and soft palate, respectively

Somatic sensory (SA) branches of Maxillary nerve (CN V2)

Brs. of superior labial nerve branch of Infraorbital nerve (CN V2) To vestibule

Somatic sensory (SA) branches of CN V1

Anterior ethmoidal n. Branches

From orbit to anterosuperior nasal cavity

Olfaction

Olfactory nerve (CN I) fibers

Visceral (chemical) sensory (VA)

Cell bodies in olfactory epithelium

Fibers arise in olfactory mucosa (lateral wall &

septum)

Fibers pass through the olfactory foramina of

cribriform plate

Synapse in the olfactory bulb

Pterygopalatine (= sphenopalatine) ganglion

Distribution hub for PARASYMPATHETICS to nasal cavity, palate, nasopharynx

Suspended by pterygopalatine nerves of CN V2

Composed of postganglionic parasympathetic cell bodies

Secretomotor (VE) to palatal, nasal, nasopharynx mucosal mucus glands & lacrimal gland

Overstimulation results in hay fever-like symptoms: watery eyes, runny nose, excessive palatal and pharyngeal mucous

Preganglionic Parasympathetic Fibers

Cell bodies in brainstem

Fibers course within CN VII

Then onto greater petrosal nerve [near geniculate ganglion]

Joins with deep petrosal n. to become nerve of the pterygoid canal

Synapse in pterygopalatine ganglion

Postganglionic fibers “hitchhike” on somatic sensory branches of CN V2 to target mucosa/glands

Innervation to Lacrimal Gland

INDIRECT: Pterygopalatine ganglion → Maxillary n. → Zygomatic branch → communicating branch → Lacrimal n. (CN V1)

DIRECT: Communicating branch direct to lacrimal gland

Postganglionic Sympathetic Fibers

Arise from superior cervical ganglion

Course on periarterial plexus of Internal Carotid artery

Fibers become Deep petrosal n.

Joins with Greater petrosal n. to become nerve of pterygoid canal

Fibers pass through pterygopalatine ganglion without synapsing

Primarily function for vasoconstriction

Pterygopalatine fossa—distribution hub for Maxillary artery

TO FACIAL-MAXILLARY REGION:

Infraorbital artery (via inferior orbital fissure/infraorbital

canal)

Superior alveolar arteries to maxillary teeth

TO NASAL CAVITY:

Sphenopalatine artery to nasal cavity

TO PALATE:

Descending palatine artery

Greater palatine artery to hard palate via greater palatine foramen

Lesser palatine artery to soft palate via lesser palatine foramen

INTERAL CAROTID ARTERY SUPPLY

From ophthalmic artery (branch of internal carotid artery)

Septal and lateral branches of anterior & posterior ethmoidal arteries

EXTERNAL CAROTID ARTERY SUPPLY

Maxillary artery (branch of external carotid artery)

To nasal cavity:

Septal branch of sphenopalatine artery: to septum and anterior hard palate (via incisive canal) with anastomosis with Greater palatine artery

Sphenopalatine artery to nasal cavity

Posterolateral branches of sphenopalatine artery: to lateral wall

Epistaxis

Nose bleed

KIESSELBACH’S PLEXUS (= LITTLE’S AREA):

Dense arterial anastomoses

Area of ~90% of all epistaxis

“G-A-S-S”

1. Greater palatine a.

2. Anterior & posterior ethmoidal aa.

3. Sphenopalatine a.

4. Superior labial a.

DRIPPING—typically venous (thin-walled, more superficial)

SPURTING—typically arterial

Nasal Venous Drainage

Plexus of veins in mucosa drain blood via:

Veins in nasal cavity play major role in thermoregulatory system of body

Veins tend to be superficial to arteries in mucosa and are thin-walled: bleed first

Danger triangle—infection can spread to cavernous sinus/dural sinuses via facial/nasal veins

Facial vein via superior labial

Sphenopalatine vein to maxillary vein/pterygoid venous plexus

Inferior ophthalmic vein (to cavernous sinus)

Nasal Lymphatics

Most of nasal cavity drains to deep superior cervical nodes, particularly jugulodigastric (pharynx pattern)

Vestibule area drains to submandibular nodes (facial pattern)

Anosmia

Loss of smell

Test unilaterally

Complaint typically is a “loss of taste” (is actually diminished “flavor”)

May be caused by injury to the olfactory nerves at or near the cribriform plate

Clue to skull fracture; May be associated with CSF rhinorrhea