Nasal Cavity & Pterygopalatine Fossa: Mon, Oct. 9

Front 1

Nasal Cavity:

Back 1

External nasal cartilages:
1. great alar
2. nasal septal
*both sets of cartilages partially bound the opening of the nasal cavity, where posteriorly, consists of only fibrofatty tissue
A. columella, the inferior aspect of nasal septus, is only mobile part of septum

External osteology:
1. piriform aperture
2. anterior nasal spine-one attachment for septum; divides nose in left and right sides
3. nasal bones (2)

Front 2

Cavity borders:

Back 2

1. roof-small contributors of frontal, ethmoid, sphenoid, nasal bones
2. floor-maxillary bone component forming hard palate, horizontal portion of palatine bone
3. medial-nasal septum
4. lateral-various bones, irregular wall nasal bones, conchae, lacrimal, palatine, maxillary bone

Front 3

Nasal Septum:

Back 3

3 main components:
1. single vomer-unpaired bone in posterior nasal cavity ("plow share")
2. perpendicular plate of ethmoid bone
3. septal cartilage
*additionally, some contributions from medial crus of greater alar cartilage, nasal bone crest, maxillary crest, palatine crest

Vomeronasal cartilage:
*additional piece of cartilage found near inferior border of nasal septum
*houses vomeronasal nerve of Jacobson, which involved in pheromone detection (rudimentary in humans)
*CC: people who are overly sensitive to scent have a greater amound of vomeronasal nerve

Front 4

Internal bony landmarks underneath mucosal layer:

Back 4

1. ethmoid bone: large part of lateral cavity
2. sphenopalatine foramen: passageway from infratemporal fossa and nasal cavity
*formed by sphenopalatine notch, vertical plate of palatine bone, and anterior wall of sphenoid bone
3. inferior concha (inferior turbinate): unpaired bone on either side, not attached to another bone
4. superior and middle conchae: both from ethmoid
5. ethmoid bulla: protrusion found underneath middle concha
6. uncinate process: hook extending from ethmoid bone
7. semilunar hiatus: space formed when ethmoid bulla and uncinate process are covered in mucosa
**CC: important for draining various paranasal sinuses into nasal cavity/e.g. frontal sinus drains into semilunar hiatus via nasofrontal duct

Front 5

Nasal relations:

Back 5

1. Pituitary gland:
*most direct way to access gland through nose; transnasal approach
2. Hiatuses:
*found below conchae
a. nasolacrimal duct- begins in medial aspect of orbit and drains underneath (1cm posterior to anterior edge) inferior concha (meatus)
*duct usually has a one way valve called valve of Hasner

Front 6

Features of nasal cavity: lateral

Back 6

1. vestibule: part of cavity coated with epithelia
2. vibrissae: hair associated with vestibule; DO NOT have erector pili muscles
*hairline marks junction between epidermis and respiratory epithelium
3. limen nasi: another marker for upper edge of vestibule formed by lateral nasal and greater alar cartilages
4. agger nasi: mound of small ethmoid air cells, which is anterior to middle meatus

*upper 1/3 of cavity referred to as olfactory part of respiratory cavity b/c of terminal portions of olfactory nerves
*lower 2/3 present for air passage

Front 7

Olfactory nerves (CNI):

Back 7

**15-20 pairs come into cavity through cribiform plate
**most commonly injured cranial nerve
**CC: each nerve has sheath of all mater layers, therefore disrupting them can create conduit between nasal and cranial cavities (CSF rhinorrhea can lead to meningitis)
*ability of nerve to regenerate decreases with age
*olfactory neuroepithelium: highest concentration of olfactory nerve terminations (ceiling of upper 1/3 cavity)

Front 8

Other nerves of cavity:

Back 8

1. anterior ethmoidal: branch of ophthalmic; gives branches to lateral and medial aspect of cavity before terminating as external nasal nerve on tip of nose
2. nasopalatine: runs on either side of vomer then enters incisive canal in hard palate; communicates with greater palatine
3. greater palatine: runs through and on under surface of hard palate
4. Majority of nasal cavity innervation is from branches of maxillary nerve (V2)
a. maxillary nerve suspends pterygopalatine ganglionin PF
b. all branches run through PG and disseminate post-ganglionic fibers through branches of maxillary out to mucosa
**CC: nerves from PG allow you to lacrimate and innervates nasopalatine glands which produce mucus

Front 9

Arterial Supply:

Back 9

1. sphenopalatine artery: main supply; a terminal branch of maxillary
*enters cavity through sphenopalatine foramen, then branches in to multiple arteries that supply cavity
2. anterior and posterior ethmoidal arteries: from ophthalmic
3. greater palatine: off maxillary
4. superficially, facial artery

**CC: anastomosis from branches of ICA (ophthalmic) and branches of ECA in portion of cavity known as Kiesselbach's (or Little's) area/ most common site of epistaxis (bleeding through eroded mucosa)
5. Cavernosi concharum: alot of vascularization over conchae to increase surface area for warming of inhaled air/ named for resemblance to corpus cavernosum

Veins:
1. veins primarily lead through sphenopalatine foramen and then use pterygoid venous plexus to drain
2. also some communication through ethmoidal foramina
**CC: anterior and posterior ethmoidal veins can connect nasal cavity to superior ophthalmic vein

Lymphatics:
1. most drain back through retropharyngeal and into deep lymph chain

Front 10

Paranasal air sinuses:

Back 10

**outgrowths of nasal cavity
**paired, named for bones they occupy, and surrounded by diploic space of contiguous bones

1. Maxillary
2. ethmoidal air cells
3. frontal
4. sphenoid: underneath sella turcica
*all heavity innervated with sensory fibers

Newborn sinuses:
*no present sinuses

Unknown function of sinuses:
1. do lighten skull
2. do give resonance to voice

Front 11

Frontal Sinus:

Back 11

1. communicates with and drains its mucus into middle meatus through frontonasal duct
2. innervated by supraorbital nerve (V1)
3. size is variable
4. related to anterior cranial fossa

**CC: 1. eskimos have no frontal sinus
2. pilots use A-P x-rays for ID instead of dental
3. possible to erode through posterior wall and affect frontal lobe

Front 12

Ethmoid sinuses:

Back 12

1. 3-18 pairs
2. 3 locational groups: posterior, middle, anterior
3. anterior drain into semilunar hiatus
4. middle drain into hiatus via ethmoidal bulla or middle meatus
5. posterior drain into superior meatus
6. innervation primarily by anterior and posterior ethmoidal nerves, additionally by branches from PG

**intimately related to orbit; separated by lamina papyracea-sinusitis can erupt through bone and infect orbit
**just lateral to posterior ethmoidal sinus is optic nerve

Front 13

Sphenoid sinuses:

Back 13

1. most variable sinus
2. drains into small groove between superior concha an dsphenoid bone calle sphenoethmoidal recess
2. opening to sinus is its upper front wall, which slows drainage
*bacteria thrive in this static environment
3. innervation from posterior ethmoidal nerve and through branches of PG
4. associated with middle cranial fossa

Structures related to sinus:
1. optic nerve: superolateral part of sinus
2. ICA often erodes into bony border of sinus
3. maxillary nerve and nerve to pterygoid canal (runs in floor of sinus)

Front 14

Maxillary sinuses:

Back 14

"Antrum of Highmore"

1. most commonly infected
2. drains into semilunar hiatus (more superiorly than sphenoid sinus)
3. innervated by anterior, middle (infraorbital), and posterior (V2) superior alveolar nerves
**CC: toothache can accompany maxillary sinusitis b/c of superior alveolar nerves innervating both
4. ostium is in medial superior border of sinus

**CC: maxillary sinus is downstream from frontal sinus-possible for infected frontal sinus to drain inferiorly and secondarily infect maxillary

Front 15

Pterygopalatine Fossa (PF):

Back 15

1. 2 x 1 cm, pyramidal space inferior to apex of orbit and lateral to nasal cavity
2. just anterior to pterygoid processes of sphenoid and posterior to maxilla; close association with vertical part of palatine bone
3. arteries associated: psterior superior alveolar, descending palatine, pterygoid canal, pharyngeal, sphenopalatine

Things leading into and out:
A. Four canals: vidian (pterygoid canal), vomerovaginal, palatovaginal, greater palatine canal
B. Two foramina: rotundum (V2 exits), sphenopalatine (between PF and nasal cavity)
C. Two fissures: inferior orbital, pterygomaxillary

Front 16

Borders of PF:

Back 16

1. Lateral: pterygomaxillary fissure (slit between pterygoid processes and maxilla)
2. Medial: perpendicular plate of palatine with sphenopalatine foramen in superior aspect (leads to nasal cavity)
3. Posterior: vidian canal and foramen rotundum
4. Anterior: maxilla with IOF, posterior superior alveolar foramen
5. Roof: greater wing of sphenoid and SOF
6. Inferior: pyramidal process, palatine canal, oral cavity

Front 17

3 associated roots of PG:

Back 17

1. parasympathetic via greater petrosal nerve (pre-synaptic)
2. sympathetic via deep petrosal nerve (post-synaptic)
3. small sensory suspended from maxillary nerve

**branches of PG have wide distribution: sphenoid sinus, posterior ethmoidal cell, nasal cavity (nasal glands), hard and soft palates, palatine tonsil, orbit

Front 18

PG:

Back 18

1. pterygopalatine nerves suspend ganglion
2. nerve of pterygoid canal enters posterior part of PF and synapses on PG
3. greater petrosal @ level of geniculate ganglion will enter middle cranial fossa and eventually unite with deep petrosal in PC then leave and synapse on PG

**CC: 1. pterygopalatine neuralgia-continuous tearing and headaches; vidian neurectomy possible Tx
2. if nerve damage occurs, lesser petrosal nerves join with greater petrosal during regeneration, resulting in crocodile tears
*normally, greater petrosal goes to lacrimal gland, lesser to parotid-thinking about eating stimulates lesser petrosal, yet now it leads to lacrimation instead of salivation