Download Nasal anatomy

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NASAL ANATOMY & PHYSIOLOGY
EMBRYOLOGY
 the frontonasal prominence, is responsible for nasal development during the third to tenth weeks of
gestation
 Migrating neural crest cells populate the frontonasal prominence and form the nasal or olfactory placodes
1. Week 5: pair of ectodermal thickening form on frontonasal process and enlarge forming nasal placodes
2. Week 6: ectoderm at center of each pit invaginates to form nasal pit, dividing the rims into lateral and
medial nasal processes.
a. Mesenchymal proliferation around the nasal placodes allows the horseshoe-shaped medial and
lateral nasal prominences to develop
b. The invagination into mesenchyme at the point of fusion between the maxillary process and the
lateral nasal process forms the nasolacrimal duct
c. Fusion of the two medial nasal processes form the nasal bridge and septum. The inferior tips of
the medial nasal process fuse to form the intermaxillary process – becomes philtrum
d. nasal pits grow backward and evolve into the early nasal fossae.
e. Invagination of these fossae is halted by the nasobuccal membrane
3. Week 7: nasal fin grows from the floor of the nasal sac to separate oral from nasal cavity
a. This then thins down to form the oronasal membrane. This ruptures to form an opening –
primitive choana
b. The floor of the nasal cavity forms from the posterior extension of the intermaxillary process –
this is the primary palate
c. At the same time, the cells lining the walls of the nostrils proliferate to form epithelial plugs,
which obliterate the nostrils.
4. Week 8-9: Medial walls of maxillary process form palatine shelves.
a. These grow downward and at the end of week 9, rotate rapidly upward (right first then left –
thought to be due to rapid synthesis and hydration of hyaluronic acid) to fuse (ventral to dorsal) –
forming secondary palate.
b. At the same time, downgrowth from the frontonasal process forms the nasal septum, with an
opening posteriorly (definitive choana).
5. Week 13-24
a. nostrils reopen by resorption of the epithelial plug
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 medial nasal process ultimately gives rise to one half of the nasal septum and the medial crus of the lower
lateral alar cartilage.
 The lateral nasal process develops into the external wall of the nose, nasal bones, upper lateral cartilage,
alae, and lateral crus of the lower lateral cartilage.
 The apex and dorsum of the nose come from the frontonasal process
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ANATOMY
External Nose
Nasal Vaults (Sheen)
1) Bony vault
a. comprised of paired nasal bones, as well as the ascending frontal process of the maxilla
b. narrowest above the canthal level, and have increased thickness in this area
c. osteotomies are rarely indicated above this area in that is quite narrow and the bone is thick in
this area
2) Upper Cartilaginous Vault
a. upper lateral cartilages underlay the nasal bones for 6-8 mm and also underlay the lower
lateral cartilages in the scroll area between the upper and lower lateral cartilages.
b. keystone area is defined by the junction of the upper laterals with the nasal bones and the
septum. Contour here is T-shaped.
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c. This contour of the nasal dorsum, specifically the keel-shaped portion of the dorsum, must be
reconstructed or maintained in rhinoplasty or nasal reconstruction, with the widest area being
in the keystone area
3) Lower Lateral Cartilaginous Vault
a. comprised of the medial, middle, and lateral crura of the lower lateral cartilage, alae and alae
lobules, nostril vestibule and sills, columella and membranous septum (area between caudal
septum and columella)
Cartilages
1. Upper lateral (UL) - Caudal border forms internal valve.
2. Lower lateral (LL, alar) - Overlap UL and lie more superficial. Medial, middle and lat crura.

Lateral crura determines the volume, size, and position of the nasal lobules.
3. Accessory cartilages(3-4) - join lateral crus to piriform aperture.

First underlies the alar crease

Second attached to the piriform aperture

Third forms the internal nostril fold on the nasal sill
4. Septal – cartilage and bones
Bones of the Septum:
1. perpendicular plate of the ethmoid
2. vomer
3. nasal crest of maxilla
4. nasal crest of palatine bone
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Landmarks
 Radix, dorsum (both bony and cartilaginous), supra-tip, tip, columella.
 Radix - located where the nasal bones project from the frontal bone. In whites, this nasofrontal angle
usually lies at the level of the superior tarsal crease with the eyes looking forward. At the radix, the nose
projects beyond the supratarsal fold on lateral view. From this perspective, the distance from the canthal
ligament to the nasion (ie, radix projection) should be about one fourth to one third of the nasal length.
 Lobule - lower mobile part of the nose (tip, alae, columella and membranous septum).
 Nasal tip - extends longitudinally from the supratip to the columella breakpoint and transversely between
the dome-defining points.
 Angles: naso-frontal, septal (between dorsal and caudal edges of sepal cartilage), tip-columella, nasolabial.
 critical fixed anatomic landmark of the nose is the medial canthal ligament, which corresponds with the
desired level of the transverse fracture line. The floor of the anterior cranial fossa is above this point.
 The nasofrontal suture is 10.7 mm above the intercanthal line, and the intervening solid “bony triangle” is
virtually impossible to narrow by digital pressure or to deepen by rasping.
 dorsal hump is predominantly (57.4%) cartilaginous rather than bony (42.6%).
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 Superior 2/3rd of the upper laterals are joined to the dorsal septum as a single cartilaginous unit. The dorsal
border of the cartilaginous septum progresses from a Y with a supraseptal depression at the keystone area,
to a T and eventually to an I by the septal angle.
 alar domes project far above and caudal to the septal angle, thus does not give direct septal support for the
tip.
Triangles
 Soft triangle - anterior to the nostril in the angle between the medial and lateral crura. Do not incise as it
heals with a notch. Susceptible to grooving and webbing into stenosis. Rim incision should follow caudal
border of lower laterals.
 Weak triangle - In the supra-tip area between the diverging lateral crura into which the septal angle fits.
(scroll area)
Bony lateral walls
1. maxilla (frontal process)
2. Palatine bone(perpendicular plates)
3. lacrimal bone
4. Ethmoid bone (nasal conchae, cribriform plate)
5. Sphenoid (crest)
6. Nasal bones

widest at the nasofrontal suture (14 mm), narrowest at the nasofrontal angle (10 mm), and then
widened again to a maximum width of 12 mm some 9–12 mm inferior to the nasofrontal angle.
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
thickest superiorly at the nasofrontal angle (average 6 mm) and progressively thinned toward the
tip.
7. Frontal (spine)
Muscles



4 principal groups: the elevators, the depressors, the compressor, and the dilators.
a)
Elevators: Procerus(1) and levator labii superioris alaeque nasi (2)
b)
Depressors: alar head of nasalis (4) and depressor septi nasi (5)
c)
Compressor: transverse head of nasalis (6)
d)
Dilators are the dilator naris anterior(8) and posterior.
The muscles are interconnected by an aponeurosis termed the nasal superficial musculoaponeurotic
system (SMAS).

Depressor septi - originates from orbicularis oris to the medial crura, shortens the upper lip, and can
decrease tip projection with animation

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Blood supply
1. angular artery/ dorsal nasal artery to sidewalls
2. lateral nasal (facial) - located in the subdermal plexus 2–3 mm superior to the alar groove.
3. anterior ethmoidal artery – external nasal artery (lobule)
4. superior labial artery – septal branch (columella)

Nasal tip blood supply is from lateral nasal (present in 100%) and septal branch (70%). Thus tip defatting
is RISKY.

Exercise caution with previous alar base excisions or if the alar base incisions extend more than 2mm
above the alar groove in which the lateral nasal artery is damaged bilaterally.
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1 = dorsal nasal artery
2 = lateral nasal artery
3 =angular artery
4=columella branch
Nerve Supply
1. external nasal nerve - branch of anterior ethmoidal – nasociliary (V1)
2. supratrochlear nerve – from frontal branch (V1)
3. infratrochear nerve – from nasociliary (V1)
4. nasal branches of infraorbital nerve (V2)
Anatomy of the external nasal nerve(Han PRS Oct 04)
 numbness to nasal tip in 66-100% post rhinoplasty - Recovery is thought to be attributable either to
recovery of the severed nerve itself or to collateral sprouting from the contributory small branches of the
infratrochlear and infraorbital nerves supplying the adjacent areas of nasal skin
 Course
i. nasociliary nerve, a branch of the ophthalmic division
ii. anterior ethmoidal nerve through the anterior ethmoidal foramen 24mm from the orbital rim
iii. runs in a groove in the cranial aspect of the cribriform plate
iv. enters the nasal cavity, giving off two internal nasal branches, and lies on the inner aspect of the
nasal bones before emerging from their caudal edges as the external nasal nerve
v. emerges between the nasal bone and the upper lateral cartilage at an almost consistent distance of 6.5
to 8.5 mm lateral to the nasal midline
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 Nerve branching patterns
Lymphatics
Drains to submandibular glands
The major arterial, venous, and lymphatic vasculature courses in or above the musculoaponeurotic layer of
the nose. Disruption of this layer with supratip debulking may compromise tip vascularity
Internal Nose
Nasal cavity
 Extends from the external(anterior) nares (nostrils) to posterior end of nasal septum
 Opens into nasopharynx through the internal(posterior) nares
 Mainly lined by pseudostratified ciliated columnar epithelium
Vestibular area is just inside nose, lined by hair bearing skin
Septum
 4 bones:
1. ethmoid (perpendicular plate)
2. vomer
3. maxilla (anterior nasal spine, nasal crest, incisive canal, palatine process)
4. palatine bone (nasal crest and posterior nasal spine, horizontal plate)
 Cartilage - septal angle located in the supra-tip region. Nearly always deviated from midline.
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 Membranous - just above columella
 Functions as a shock absorber to prevent nasal fractures.
Folds
 Posterior vestibular fold - The posterior continuation of the internal valve to the piriform aperture separates the vestibule from the fossa proper.
 Anterior narial fold - The medial extension of the alar border which limits the caudal extent of the
vestibule.
Lining
 Vestibule - Squamous epithelium with numerous vibrissae and sebaceous glands. Ends at the caudal
margin of the lower lateral.
 Nasal fossa - Mucous membrane:
i) resp portion: pseudostratified, columnar, ciliated epithelium. Delicate and must be preserved.
ii) olfactory portion: superiorly, not ciliated, yellowish.
Turbinates
i) Superior
olfactory
ii) Middle
secretes mucous
iii) Inferior
regulates air flow

Above superior conchae – sphenoethmoidal recess (ostium of sphenoidal air sinus)

Superior meatus – posterior ethmoidal air cells

Middle meatus – Frontal sinus, anterior ethmoidal ostia, middle ethmoidal ostia, maxillary sinus

Inferior meatus – nasolacrimal duct
External nasal valve

Corresponds to alar rim

Collapse associated with facial palsy, iatrogenic injuries, trauma
Internal nasal valve

The internal nasal valve involves the area bounded by caudal border of the upper lateral cartilage,
septum, nasal floor, and anterior head of the inferior turbinate.
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
This comprises the narrowest portion of the nasal airway. Generally, an angle wider than 15° is needed in
this area.

Nasal valve provides approximately 50% of total airway resistance.
Jacobson’s organ (vomeronasal organ)
 Said to be vestigial in humans, but in other vertebrates plays a role in pheremone detection and therefore
reproduction.
 All humans have vomeronasal pits in the anterior 1/3 of the nasal septum.
 The pits are 2-8 mm long and lined by unique, pseudo-stratified, columnar epithelium which seems to
contain 2 different kinds of receptors (?function).
 Sub-mucoperichondrial dissection does not seem to harm these organs.
Blood supply
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 Lateral wall - supplied by the
1. sphenopalatine artery posteroinferiorly
2. anterior and posterior ethmoid arteries superiorly.
3. alar branch from facial artery
 Septum –
1. sphenopalatine
2. anterior and posterior ethmoid arteries
3. septal branch of superior labial artery (anteriorly)
4. ascending branch of greater palatine
 The Kiesselbach plexus, or the Little area, represents a region in the anteroinferior third of the nasal
septum, where the chief blood supplies to the internal nose converge (anterior ethmoid, ascending branch
of greater palatine artery , septal branch of superior labial and sphenopalatine arteries)
 Woodruffs plexus – pharyngeal and posterior nasal artery of sphenopalatine.
 Venous drainage – follows arteries back to pterygoid plexus. Valveless veins also drain into cavernous
sinus.
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Nerve Supply
 Lateral wall
1. anterior ethmoidal nerve
2. Olfactory nerve
3. lateral posterior superior nasal branches (pterygopalatine ganglion)
4. infraorbital nerve
5. anterior superior alveolar nerve
6. posterior inferior nasal branches (greater palatine)
 Septum
1. anterior and posterior ethmoidal nerves
2. olfactory nerve
3. medial posterior superior nasal
4. nasopalatine via sphenopalatine foramen

Parasympathetic supply for mucous membranes – superior salivary ganglion, nevus intermedius, greater
petrosal nerve (joins with deep petrosal nerve) forms nerve of pterygoid canal (Vidian), and joins up to
pterygopalatine ganglion.
Lymphatics

Follows veins rather than arteries

Anteriorly, drain to level I and II (submandibular and deep cervical nodes)

Posteriorly, to retropharyngeal nodes (one to three in number, lie in the buccopharyngeal fascia)
NASAL PHYSIOLOGY
Functions
1. Principle respiratory airway
2. Olfaction (Bowman’s glands secrete a serous fluid which dissolves air-borne particles and thus allows
presentation to the olfactory cells)
3. Resistance

Resistance is important in nasal function

Turbulence (from conchae) optimizes inspiratory air contact with the mucous membrane.
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
Resistance must remain within certain limits for the perception of normal breathing. If it is too
high or too low, a sensation of obstruction may occur.
4. Humidification
 warming: to 31o-37o
 filtering: (hairs, cilia, lysozyme)
 moistening.: 1 litre per day to get to 75% humidity
5. Phonation
6. Self cleaning

mucous blanket and cilia

Nasal cilia beat posteriorly towards the nasopharynx whereas sinus cilia beat towards the ostia.
Nasal cycle
 Unilateral nasal obstruction at any given time due to and alternating congestion (or engorgement) and
decongestion of the inferior turbinates on one side and the other.
 Shrinkage of one side is associated with secretion of serous fluid and mucous and occurs while the other
side becomes engorged.
 Total airway resistance remains relatively constant
 Occurs in 80% of individuals. The cycle lasts 30 minutes to 4 hours.
Factors influencing nasal air flow
1. Nostrils and vestibule
 Normally parabolic curves.
 Retrousse tip (collapsed) directs flow dorsally.
 naso-labial angle directs flow along floor.
2. Internal nasal valves
 Cartilage and muscle important.
 Normal septal-UL cartilage angle > 15o.
 Inspiration es negative pressure and tends to collapse valves inward
 Excess excision of alar cartilages at rhinoplasty can cause problems with the nasal airway.
3. Septum
 Deviation is not the only pathology that can affect the nasal airway.
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 Mucosal hypertrophy, adhesions, cartilagenous thickening, septal angulation can also adversely
affect the airway.
 Most people have a septum that is deviated to some degree.
4. Turbinates
 Errectile properties therefore function as a valve.
 Sympathetic vasoconstriction opens the airway and vica versa.
 Chronic enlargement, hypertrophy and polypoid degeneration can affect the airway.

Controversial whether aesthetic rhinoplasty affects nasal air flow. Courtuss believes that infracturing is
done cephalad to the nasal airway and should not impact on air flow., and thus only if the nasal valves are
adversely affected or a septal procedure results in perforation that air flow may be affected. Others
(Guyuron, Ford) believes that lateral osteotomies will reduce air flow.
Rhinitis classification
1. Allergic

triggered by exposure to allergens

nasal pruritus, clear rhinorrhea, postnasal drip, and nasal obstruction caused by inflammation of the
nasal mucous membranes
2. Infective

Acute or Chronic
3. Vasomotor

characterized by prominent symptoms of nasal obstruction, rhinorrhea, and congestion.

Exacerbated by certain odors (e.g., perfumes, cigarette smoke, paint fumes, inks); alcohol; spicy foods;
emotions; and environmental factors such as temperature, barometric pressure changes, and bright
lights.

Theories: increased cholinergic glandular secretory activity (for runners), heightened sensitivity to
usually innocent stimuli and autonomic system dysfunction
4. Atrophic

characterised by squamous metaplasia followed by atrophy.

The nose becomes filled with foul smelling crusts

Cause unknown but may follow radical nasal surgery, end stage of rhinitis medicamentosa, or may be
due to chronic infective with specific organisms.
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5. Hyperplastic

Associated with nasal polyposis
6. Medicamentosa

condition of rebound nasal congestion brought on by overuse of intranasal vasoconstrictive
medications.

Typically occurs after 5-7 days of medication use.
7. Post-rhinoplastic

primarily the result of the interplay between 2 factors.
i. Unrecognized preexisting nasal conditions (eg, deviated nasal septum, turbinate hypertrophy, mucosal
disease)
ii. decrease in the nasal valve area after rhinoplasty

Many patients with nasal obstruction and considered for septoplasty actually have vasomotor rhinits and
will improve with time. Careful differentiation of anatomical vs physiological obstruction must therefore
be done.
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NASAL AESTHETICS

The underlying bony skeleton defines the soft tissue contours.

Ideal measurements
o Nasal length (radix to tip =4cm) = 2/3rd of mid facial height (glabella to alar base plane – 6cm)
o distance from the canthal ligament to the nasion (ie, radix projection) should be about one fourth
to one third of the nasal length
o Ideal nasal tip projection (subnasale to tip) = 2/3rd of nasal length
o 50-60% of nasal height should lie anterior to the most projecting part of upper lip
o Bony base should be ¾ of alar base
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o Projection angle for radix – 30-36 ( in relation to line from glabella to pogonion)
o Nasal dorsum is outlined by 2 slightly curved divergent lines extending from medial brow to tip
defining points
o Width of alar base=intercanthal distance=width of 1 eye
o Lines connecting the 2 tip defining points, supratip break and alar-columella-lobular angle form 2
equilateral triangles.
o Columella-labial angle 90-105 in male, 95-110 in female. May be affected by projecting teeth or
when the caudal septum or nasal spine is prominent. Nasolabial angle – more accurate: line
perpendicular to the Frankfort horizontal, which passes through the alar facial groove. This line is
compared to a line that passes through the long axis of the nostrils. In females, the angle between
the 2 lines should be approximately 95-105°. In males, this angle should be 90-95°.
o 2-3mm columella show below the alar rim on lateral
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Measuring tip projection
A=nasofacial angle – line from glabella to pogonion (30-40deg) - affected by chin position or a sloping
forehead
B = Crumley and Landser method – distance from the mandibular profile line (menton) to the nasion and
measures projection to this line. The ratio of the length of the mandibular profile line to the projection
distance should be between 4:1 and 4.5:1. Most accurate but difficult to use
C = Goode method - uses a vertical line from the nasion to the alar facial groove. A horizontal line is drawn
through the tip perpendicular to this vertical line. The ratio of the horizontal line to the vertical line should be
0.55:0.60. Inaccurate if the maxilla protrudes or if the columella is in an abnormal position.
Aesthetic units (Gonzalles-Ulloa [1956], Millard [1981], Burget [1985])
 Borders between units are transitions of contour where shadows occur under normal lighting conditions.
1. dorsum
2. sides (between dorsum, medially and alar, below)
3. tip, including columella
4. alar lobule
5. soft triangle
Rule of thumb:
 If a defect is > 50% of a unit, the defect should be enlarged so that the whole unit is reconstructed,
provided the donor flap can cover the unit.
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 If the defect is < 50% of the unit, it is best to ignore the unit and reconstruct the defect.
Nasal subunits
Freddy Nicolle divides noses into 2 types:
a) the top heavy nose: flat naso-frontal angle and high dorsum  needs bony and septal reduction and
should give good results.
b) bottom heavy nose: low radix and small nasal bones, but large tip cartilages and excess skin 
difficult reduction. Be conservative.
Nostril shape (Farkas, 1983)
 7 types of nostril shape from longitudinal to circular to wide.
 Caucasians have type I or type II (longitudinal). Columella height about 60% (1/2-2/3) of the height of the
lobule.
 Orientals have mainly type III to V (circular).
 Blacks tend to have type VI or VII (broad, wide).
Classification of alar-columellar relationships. (Gunter PRS 1996)
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Nasal Tip


Tip defining points- two equilateral triangles from the supratip area, to the apex of the domes, to the
columellar lobule angle. Dome is the junction of middle and medial crura.

refined tip has a double-break appearance, which is associated with a supratip and infratip break. The
supratip is defined by the junction of the nasal dorsum and the nasal tip, and the infratip is defined by the
junction of the tip and columella. The span between the supratip and infratip is subsequently called the
infratip lobule and is composed of the middle crura.
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
Height of the lobule is reflected by the length of the middle crura

Tripod concept (Anderson 1971)
o right and left lateral crura comprise two legs of the tripod, and two conjoined medial crura
function as the third leg.
o Disruption of this complex and their supporting structures will alter tip morphology.

Important angles

Angle of domal definition or rotation – angle of turn from medial to lateral crura

Angle of divergence - formed by the domal angulation of adjacent middle crura (normal 60)

Increased in both these angles = bulbous tip

Increased in only angle of divergence = boxy tip

Increased cephalic slant of lateral crus = parenthesis tip (normal 15, abnormal up to 60)

Important nasal tip-supporting structures (first 3 are the major supports)
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1. Lower lateral cartilage - Size, shape, strength, and direction of torque produced by the lateral crura
is critical in defining the tip
2. Medial crura footplate – attachment to the caudal border of the quadrangular cartilage
3. Intercartilaginous ligament – fibrous connection between lower and upper laterals.
4. Dermocartilaginous ligament (Pitanguy) - situated along the midline, originates in the fascia of the
upper third of the nose, and extends down to the domal segment of the middle crus, merging into the
subseptum. influence tip-dorsum relationships. This ligament is most important in patients with a
bulbous tip and in the noses of black patients, where the convexity of the lower third of the nose
remains apparent after classic modification of the osseocartilaginous structures. Dividing and partially
resecting this dermatocartilaginous ligament allows the lower third of the nose and the nasal tip to
move upward.
5. Lateral crural complex – Connection between lateral crus and piriform aperture via a fibrous
aponeurosis with interspersed accessory cartilages. Also called sesamoid complex (Janeke and
Wright) and nasal hinge (Adamson).
6. Interdomal ligament
– loose connective tissue between paired domes of lower laterals. Aka
ligamentous sling (Janeke and Wright) or suspensory ligament
7. Membranous septum
8. Nasal spine

Excision of the cephalic rim of the alar cartilage destroys the superior support, while resection of the
caudal septum eliminates central support and an alar resection paralleling the nostril rim disrupts the
cartilaginous ring.

Preservation of tip support requires respect of the lateral crura accessory cartilage ring and judicious
resection of the caudal septum, especially at the medial crura septum junction.