Nose, nasal cavity and paranasal sinuses

Box 39.1 and Table 39.1 set out the different anatomical and clinical terms that are applied to some of the structures described in this chapter.

Box 39.1

A note on terminology

‘The advent of endoscopic sinus surgery led to a resurgence of interest in the detailed anatomy of the internal nose and paranasal sinuses. However, the official Terminologia Anatomica used by basic anatomists omits many of the structures of surgical importance. This led to numerous clinical anatomy papers and much discussion about the exact names and definitions for the structures of surgical relevance. The European position paper on the anatomical terminology of the internal nose and paranasal sinuses was conceived to re-evaluate the anatomical terms in common usage by endoscopic sinus surgeons and to compare this with the official Terminologia Anatomica ’ ( ).

Where appropriate, the terms used in this chapter are those commonly used in surgical practice as set out in the ‘European position paper on the anatomical terminology of the internal nose and paranasal sinuses’ (see Table 39.1 ). Conflicts inevitably arise but hopefully have been minimized. The terms ‘concha’ and ‘turbinate’ are often used interchangeably but anatomists rarely use the latter term, while clinicians rarely use the former; in this chapter, concha is used to describe the bony structure seen in dried skulls, while turbinate is used to describe the bony structures, together with their overlying soft tissue and mucosa, that are encountered during surgery. ‘Ethmoturbinal’ does not appear in Terminologia Anatomica but is the collective term for the superior and middle turbinates, occasionally supplemented by a supreme turbinate. With regard to the terms ‘skull base’ and ‘cranial base’, although they are frequently used as though synonymous (the term ‘skull base’ is favoured in the position paper), the anterior skull base includes the inferior surface of the facial skeleton and will therefore be distinguished from the anterior cranial base, which is delimited by the inner and outer surfaces of the anterior cranial fossa ( Ch. 34 ).

TABLE 39.1

Surgical and anatomical terminology

With permission from Lund VJ, Stammberger H, Fokkens WJ et al 2014 European position paper on the anatomical terminology of the internal nose and paranasal sinuses. Rhinology 50:Suppl 24:1–34.

	Present ‘surgical’ terminology	Rhinological and anatomical synonyms (textbooks, literature)	Terminologia Anatomica 1	Suggested English terminology (position paper)	Frequency of variant in literature ∗
1	Nasal cavity	Inner nose Cavum nasi	Cavitas nasi	*Nasal cavity*
1.1	Lateral nasal wall	Lateral nasal wall	n.e.	*Lateral nasal wall*
1.2	Floor of nasal cavity	Nasal floor	n.e.	*Nasal floor*
1.3	Nasal septum	Septum nasi	Septum nasi	*Nasal septum*
1.3.1	Cartilaginous portion	Cartilaginous part of the nasal septum Cartilaginous segment Septal cartilage Lamina quadrangularis	Pars cartilaginea (septi nasi) Cartilago septi nasi	*Septal cartilage*
1.3.2	Bony part	Bony/osseous septum Bony/osseous part of the nasal septum	Pars ossea septi nasi	*Bony septum*
1.3.2.1	Lamina perpendicularis	Perpendicular plate of ethmoid	Lamina perpendicularis ossis ethmoidalis	*Perpendicular plate of ethmoid*
1.3.2.2	Vomer	Vomer	Pars ossea septi nasi	*Vomer*
1.3.3	Membranous portion	Membranous portion	Pars membranacea septi nasi	*Membranous portion (of nasal septum)*
1.3.4	Jacobson’s organ	Vomero-nasal organ	Organum vomeronasale	*Vomero-nasal organ*
1.3.5	Septal tubercle	Tuberculum septi nasi tubercle of Zuckerkandl Morgagni’s tubercle Septal swell body	n.e.	*Septal tubercle*
1.4	Inferior turbinate	Inferior nasal turbinate Maxilloturbinal Concha inferior Lower turbinate	Concha nasi inferior	*Inferior turbinate*
1.4.1	Inferior meatus	Inferior nasal meatus Lower nasal meatus	Meatus nasi inferior	*Inferior meatus*
1.4.1.1	Nasolacrimal duct opening	Hasner’s valve (Naso)lacrimal duct ostium Ostium lacrimale	Apertura/ostium ductus nasolacrimalis	*Nasolacrimal duct opening*
1.5	Middle turbinate	Middle nasal turbinate First (persisting) ethmoturbinal First ethmoidal turbinate Middle concha Concha media	Concha nasi media	*Middle turbinate*
1.5.1	Basal lamella of middle turbinate	Ground lamella of middle turbinate Third basal lamella	n.e.	*Basal lamella of middle turbinate*
1.5.2	Paradoxically curved middle turbinate	Concave middle turbinate Inverse middle turbinate	n.e.	*Paradoxical middle turbinate*	3–26%
1.5.3	Concha bullosa (of middle turbinate)	Bullosa middle turbinate/concha	n.e.	*Concha bullosa (of middle turbinate)*	17–36% ∼50% in Turkish
1.5.3.1	Interlamellar cell	Interlamellar cell	n.e.	*Interlamellar cell*
1.6	Middle meatus	Meatus medius Middle nasal meatus	Meatus nasi medius	*Middle meatus*
1.7	Ostiomeatal complex	Ostiomeatal complex	n.e.	*Ostiomeatal complex*
1.8	Superior turbinate	Superior nasal turbinate Second (persisting) ethmoturbinal Second ethmoidal turbinate Superior concha Concha superior	Concha nasi superior	*Superior turbinate*
1.8.1	Concha bullosa (of superior turbinate)	Concha bullosa (of superior turbinate)	n.e.	*Concha bullosa (of superior turbinate)*	1–2%
1.9	Superior meatus	Superior nasal meatus Upper nasal meatus	Meatus nasi superior	*Superior meatus*
1.10	Supreme turbinate	Supreme nasal turbinate Third (persisting) ethmoturbinal Third ethmoidal turbinate Supreme concha Highest nasal concha Concha (nasalis) suprema (Morgagni)	Concha nasi suprema	*Supreme turbinate*
1.11	Supreme meatus	Supreme nasal meatus	n.e.	*Supreme meatus*
2	Spheno-ethmoidal recess	Recessus spheno-ethmoidalis	Recessus sphenoethmoidalis	*Spheno-ethmoidal recess*
3	Sphenopalatine foramen	Foramen of sphenopalatine artery	Foramen sphenopalatinum	*Sphenopalatine foramen*
4	Olfactory cleft	Olfactory ridge Olfactory groove Olfactory fissure Olfactory area	Sulcus olfactorius	*Olfactory cleft*
4.1	Olfactory fibre(s)	Olfactory fibre(s) Fila olfactoria	Fila olfactoria (sing: filum olfactorium)	*Olfactory fibre(s)*
5	Choana (plur: choanae)	Posterior nasal aperture(s) Nares posteriores	Choana (plur: choanae) Apertura nasalis posterior	*Choana*
6	Maxillary sinus	Maxillary antrum	Sinus maxillaris	*Maxillary sinus*
6.1	Maxillary sinus ostium	Maxillary opening	n.e.	*Maxillary sinus ostium*
6.1.1	Accessory maxillary ostium (plur: ostia)	Additional maxillary sinus ostium	n.e.	*Accessory ostium*	5% normal 25% CRS patients
6.1.2	Maxillary hiatus	Maxillary hiatus	Hiatus maxillaris	*Maxillary hiatus*
6.2	Infraorbital nerve canal	Infraorbital canal	Canalis infraorbitalis	*Infraorbital canal*
6.3	Zygomatic recess	Recessus zygomaticus	n.e.	*Zygomatic recess*
6.4	Alveolar recess	Recessus alveolaris	n.e.	*Alveolar recess*
6.5	Prelacrimal recess	Prelacrimal recess	n.e.	*Prelacrimal recess*
6.6	Lacrimal eminence	Eminentia lacrimalis Bulging of nasolacrimal duct	n.e.	*Lacrimal eminence*
6.7	Canine fossa	Canine fossa Fossa canina	Fossa canina	*Canine fossa*
6.8	Anterior (nasal) fontanelle	Fontanella nasal anterior	n.e.	*Anterior fontanelle*
6.9	Posterior (nasal) fontanelle	Fontanella nasal posterior	n.e.	*Posterior fontanelle*
6.10	Maxillary artery	(Internal) maxillary artery	Arteria maxillaris	*Maxillary artery*
7	Ethmoidal complex	Ethmoid Ethmoidal sinus(es) Ethmoidal labyrinth Labyrinthus ethmoidalis	Cellulae ethmoidales	*Ethmoidal complex*
7.1	Anterior ethmoidal cells	Anterior ethmoid Sinus ethmoidalis anterior Cells of anterior ethmoid Anterior ethmoid complex	Cellulae ethmoidales anteriores	*Anterior ethmoidal cells*
7.2	Middle ethmoidal cells		Cellulae ethmoidales mediae	*t.b.a.*
7.3	Posterior ethmoidal cells	Posterior ethmoid Sinus ethmoidalis posterior Dorsal ethmoidal cells Cells of posterior ethmoid	Cellulae ethmoidales posteriores	*Posterior ethmoidal cells*
7.4	Anterior ethmoidal artery	Anterior ethmoidal artery	Arteria ethmoidalis anterior	*Anterior ethmoidal artery*
7.5	Middle ethmoidal artery	Third ethmoidal artery Accessory ethmoidal artery Intermediate ethmoidal artery Arteria ethmoidalis tertia (40%)	n.e.	*Accessory ethmoidal artery*	(Var) up to 45% if it equates to any situation where >2 arteries
7.6	Posterior ethmoidal artery	Posterior ethmoidal artery	Arteria ethmoidalis posterior	*Posterior ethmoidal artery*
8	Anterior ethmoidal complex	Anterior ethmoidal cells	Cellulae ethmoidales anteriores	*Anterior ethmoidal complex*
8.1	Agger nasi	Operculum conchae mediae	Agger nasi	*Agger nasi*
8.1.1	Agger nasi cell	Pneumatized agger nasi Agger cell	n.e. (cellula ethmoidalis anterior)	*Agger nasi cell*	>90%
9	Uncinate process	Uncinate process	Processus uncinatus	*Uncinate process*
9.1	Deflected uncinate process	Doubled middle turbinate Anteriorly curved uncinate process Everted uncinate process	n.e.	*Everted uncinate process*	5–22%
9.2	Aerated uncinate process	Bullous uncinate process Pneumatized uncinate process	n.e.	*Aerated uncinate process*	1–2%
9.3	Basal lamella of uncinate process	Ground lamella of uncinate process Uncinate lamella First basal lamella	n.e.	*Basal lamella of uncinate process*
9.4	Hiatus semilunaris	Semilunar hiatus Hiatus semilunaris inferior Semilunar gap	Hiatus semilunaris	*Inferior semilunar hiatus*
9.4	Hiatus semilunaris (superior)	Hiatus semilunaris superior Hiatus semilunaris posterior Superior semilunar hiatus	n.e.	*Superior semilunar hiatus*	(Var)
9.5	Ethmoidal bulla	Bulla ethmoidalis	Bulla ethmoidalis	*Ethmoidal bulla*
9.5.1	Non-pneumatized ethmoidal bulla	Torus bullaris	n.e.	*t.b.a.*	8%
9.5.2	Bulla lamella	Second ground lamella Basal lamella of ethmoidal bulla Second basal lamella	n.e.	*Basal lamella of ethmoidal bulla*
9.5.3	Suprabullar recess	Sinus lateralis Suprabullar cell Recessus bullaris	n.e.	*Suprabullar recess*	71%
9.5.4	Retrobullar recess	Hiatus semilunaris superior	n.e.	*Retrobullar recess*	94%
9.5.5	Supraorbital recess	Supraorbital cell Supraorbital ethmoid cell Cellula orbitalis	n.e.	*Supraorbital recess*	(Var) 17%
9.5.6	Infraorbital cell	Haller cell Orbito-ethmoidal cell	n.e.	*Infraorbital cell*	4–15%
9.6	Ethmoidal infundibulum	Ethmoidal infundibulum	Infundibulum ethmoidale	*Ethmoidal infundibulum*
9.6.1	Terminal recess	Terminal recess of ethmoidal infundibulum Recessus terminalis	n.e.	*Terminal recess*	(Var) 49–85%
9.7	Frontal recess	Recessus frontalis Frontal outflow tract	n.e.	*Frontal recess*
9.7.1	Infundibular cells	Infundibular cells	n.e.	*Anterior ethmoidal cells*	(Var)
9.7.2	Lacrimal cells	Lacrimal cells	n.e.	*Anterior ethmoidal cells*	(Var) 33%
9.7.3	Nasofrontal duct	Frontal outflow tract Frontal recess	Ductus nasofrontalis	*t.b.a.*
9.7.4	Maxillary crest	Lacrimal crest Maxillary line	n.e.	*Lacrimal bulge*
9.7.5	Ethmoidal crest	Crista ethmoidalis Ethmoidal crest of the palatine bone	Crista ethmoidalis	*Ethmoidal crest*
9.7.6	Frontal sinus drainage pathway	Nasofrontal duct Frontal outflow tract Frontal recess	n.e.	*Frontal sinus drainage pathway*
10	Frontal sinus	Frontal sinus	Sinus frontalis	*Frontal sinus*
10.1	Interfrontal septum	Frontal sinus septum	Septum sinuum frontalium	*Frontal intersinus septum*
10.2	Frontal sinus infundibulum	Frontal sinus infundibulum	n.e.	*Frontal sinus infundibulum*
10.3	Intrafrontal cells	Frontal sinus cells Kuhn type 3/4 cells	Bullae frontales (sing: bulla frontalis)	*Frontoethmoidal cells*	(Var)
10.4	Intersinus septal cell	Intersinus septal cell	n.e.	*Intersinus septal cell*
10.5	Frontal bulla	Frontal bulla	n.e. (cellula ethmoidalis anterior)	*t.b.a.*	(Var)
10.6	Frontal sinus ostium	Frontal ostium Opening of frontal sinus	Apertura sinus frontalis	*Frontal sinus opening*
10.7	Frontal beak	Nasal beak Superior nasal spine	Spina frontalis (ossis frontalis) Spina nasalis interna	*Frontal beak*
11	Posterior ethmoidal complex	Posterior ethmoidal cells	Cellulae ethmoidales posteriores	*Posterior ethmoidal complex*
11.1	Onodi cell	Spheno-ethmoidal cell Gruenwald cell	n.e. (cellula ethmoidalis posterior)	*Sphenoethmoidal cell*	4–65% 8–14% Caucasians, 26–29% Asians
11.2	Basal lamella of superior turbinate	Fourth basal lamella	n.e.	*Basal lamella of superior turbinate*
11.3	Lamina papyracea	Medial orbital wall Papyraceous lamina	Lamina orbitalis ossis ethmoidalis	*Lamina papyracea*
11.4	Orbital apex	Orbital apex	n.e.	*Orbital apex*
11.5	Anulus of Zinn	Common tendinous ring Common anular tendon	Anulus tendineus communis	*Anulus of Zinn*
11.6	Ophthalmic artery	Ophthalmic artery	Arteria ophthalmica	*Ophthalmic artery*
12	Sphenoid sinus	Sphenoid sinus	Sinus sphenoidalis	*Sphenoid sinus*
12.1	Intersphenoidal septum	Intersphenoidal septum Sphenoid sinus septum	Septum sinuum sphenoidalium	*Sphenoid intersinus septum*
12.2	Accessory sphenoidal septum (plur: septa)	Incomplete sphenoidal septations Partial sphenoidal septations Sphenoid sinus subseptations	n.e.	*Sphenoid septations*	(Var) 76%
12.3	Sphenoid sinus ostium	Sphenoid (sinus) ostium Sphenoid (sinus) opening Natural sphenoid ostium	Ostium (apertura) sinus sphenoidalis (plur: ostia sinuum sphenoidalium)	*Sphenoid sinus ostium*
12.4	Planum sphenoidale	Sphenoid sinus roof Jugum sphenoidale Sphenoidal yoke	Jugum sphenoidale	*Planum sphenoidale*
12.5	Sellar floor	Floor of sella Sellar bulge	n.e.	*Sellar floor*
12.6	Vidian canal	Pterygoid canal Canalis nervi pterygoidei	Canalis pterygoideus	*Pterygoid (Vidian) canal*
12.7	Foramen rotundum	Canalis rotundus Round foramen	Foramen rotundum	*Foramen rotundum*
12.8	Lateral recess of sphenoid sinus	Lateral recess of sphenoid sinus	n.e.	*Lateral recess of sphenoid sinus*	(Var)
12.9	Optic tubercle	Optical nerve tubercle Prominentia nervi optici	Tuberculum nervi optici	*Optic nerve tubercle*
12.9.1	Optic nerve canal	Eminentia nervi optici Optic nerve bulging Optic nerve canal contour	Canalis opticus	*Optic nerve canal*	(Var)
12.9.2	Carotid artery prominence	Prominentia canalis carotici	n.e.	*Carotid artery bulge*	(Var)
12.9.3	Optico-carotid recess	Carotid-optical recess Infraoptical recess	n.e.	*Optico-carotid recess*	(Var)
12.9.4	Sternberg’s canal	Canalis craniopharyngicus lateralis	n.e.	*Lateral craniopharyngeal (Sternberg’s) canal*	4% adults
13	Sphenoidal rostrum	Rostrum	Rostrum sphenoidale	*Sphenoid rostrum*
14	Vomerovaginal canal	Vomerovaginal canal	Canalis vomerovaginalis	*Vomerovaginal canal*
15	Palatovaginal canal	Palatovaginal canal	Canalis palatovaginalis	*Palatovaginal canal*
16	Skull base	Cranial base Basicranium	Basis cranii	*Skull base*
16.1	Inner skull base	Internal surface of cranial base	Basis cranii interna	*Inner skull base*
17	Anterior cranial fossa	Anterior cranial fossa	Fossa cranii anterior	*Anterior cranial fossa*
17.1	Olfactory fossa	Ethmoidal notch Fovea ethmoidalis	n.e.	*Olfactory fossa*
17.2	Cribriform plate	Lamina cribrosa Roof of inner nose	Lamina cribrosa (ossis ethmoidalis)	*Cribriform plate*
17.2.1	Cribriform foramina	Cribriform openings	Foramina cribrosa	*Cribriform foramina*
17.2.2	Lateral lamella of cribriform plate	Lateral lamella of cribriform plate	n.e.	*Lateral lamella of cribriform plate*
17.3	Ethmoidal roof	Foveae ethmoidales (ossis frontalis)	n.e.	*Ethmoidal roof*
17.4	Crista galli	Crista galli	Crista galli	*Crista galli*
17.4.1	Pneumatized crista galli	Pneumatized crista galli	n.e.	*Pneumatized crista galli*	13%
17.5	Foramen caecum	Foramen caecum	Foramen caecum	*Foramen caecum*	Open (Var: 1.4%)
18	Middle cranial fossa	Middle cranial fossa	Fossa cranii media	*Middle cranial fossa*
18.1	Sella	Hypophysial fossa Pituitary fossa	Sella turcica	*Sella (turcica)*
18.2	Sellar tubercle	Suprasellar notch	Tuberculum sellae	*Tuberculum sellae*
18.3	Dorsum sellae	Dorsum sellae	Dorsum sellae	*Dorsum sellae*
18.4	Anterior clinoid process	Anterior clinoid process	Processus clinoideus anterior (plur: processus clinoidei anteriores)	*Anterior clinoid process*	Pneumatized (Var: 16.5%)
18.5	Posterior clinoid process	Posterior clinoid process	Processus clinoideus posterior (plur: processus clinoidei posteriores)	*Posterior clinoid process*
19	Posterior cranial fossa	Posterior cranial fossa	Fossa cranii posterior	*Posterior cranial fossa*
19.1	Clivus	Clivus	Clivus	*Clivus*

Abbreviations: n.e., non existent; sing., singular; plur., plural; t.b.a., to be abandoned.

∗ The frequency of specific variations in the anatomy varies considerably in the literature, which relates to the definitions used, the methodology utilized, i.e. anatomical dissection or imaging, whether the study included normal controls and/or patients with chronic rhinosinusitis (CRS), and the ethnicity of the subjects.

Nose

The nose is the first part of the upper respiratory tract and is responsible for warming, humidifying and, to some extent, filtering inspired air. It also houses the olfactory epithelium, which contains olfactory receptor neurones responsible for detecting airborne odorant molecules.

The nose may be subdivided into an external nose, which opens anteriorly on to the face through the nostrils or nares, and an internal chamber, divided sagittally by a septum into right and left cavities, which open posteriorly into the nasopharynx through the posterior nasal apertures or choanae. The nasal cavities are housed in a supporting framework composed of bone and fibroelastic cartilages. The larger bones in this framework contain air-filled spaces lined with respiratory epithelium, described collectively as the paranasal sinuses. The sinuses and the nasolacrimal ducts drain into the nasal cavity via openings in its lateral walls ( Fig. 39.1 ).

Fig. 39.1, An overview of the spatial relationships between the nasal cavity, paranasal sinuses and nasolacrimal ducts.

External Nose

The external nose is a pyramidal structure located in the midline of the midface and attached to the facial skeleton. Its upper angle or root is continuous with the forehead, and its free tip forms the apex, which projects anteriorly. The overall shape of the external nose is very variable. The lateral surfaces of the nose unite in the median plane to form the dorsum, which is narrowest at the medial canthus. The lobule is an area containing the tip of the nose. Its base contains two ellipsoidal apertures, the external nares or nostrils, which open on to its inferior surface, separated by the nasal septum and columella. The columella usually projects below the alar margin. The alar sulcus is a groove in the skin bounding the nasal alae above and joining the nasiolabial sulcus. Below, it curves towards the tip of the nose but does not reach it.

Facial and nasal proportions

The proportions of the nose and face, both from in front and from the side, are of enormous significance to the rhinoplastic surgeon. Aesthetic proportions of the nose vary depending on sex, age, ethnicity and facial characteristics; however, ranges of normality are described to assist in aesthetic assessment ( ). The female nose is slightly smaller and narrower than the male nose; it is often slightly concave in profile view, with a slightly obtuse nasolabial angle (increased tip rotation). In terms of overall proportion, the face may be divided into horizontal thirds and vertical fifths, with the nose occupying the middle section of each. The width of the nose is roughly 70% of the length; the width of the alar base is usually equal to the intercanthal distance. The height of the nose is defined by tip projection, where the proportion of the length of a line from the tip to the alar groove to the length of a line from nasion to alar groove is in the range of 0.55–0.60. The nasolabial angle, reflecting upward rotation of the nose from the upper lip, normally lies within a range of 105–120° in females and 90–105° in males. On basal view, the nose is roughly shaped as an equilateral triangle. The nares usually measure 1.5–2 cm anteroposteriorly and 0.5–1 cm transversely, and are narrower in front; they occupy approximately two-thirds of the height of the base. The midline columella, containing the caudal end of the nasal septum and the medial crura of the lower lateral cartilages, usually extends 3–5 mm below the nares on lateral views ( Fig. 39.2 ).

Fig. 39.2, The adult male nose. A , Basal view. B , Frontal view. The face can be divided into horizontal thirds and vertical fifths, with the nose filling the central segment in terms of both width and height. The basal view may also be divided into horizontal thirds, with the nostrils filling the lower two-thirds.

Skin and soft tissue

The skin and soft tissue covering the nose vary in thickness. They are usually thin over the dorsum in the mid third, especially at the osseocartilaginous junction, the rhinion, and loosely connected to the nasal aponeurosis and the muscle fibres that fan out within it. It is thicker over the nasofrontal angle, and at the tip, where it has numerous large sebaceous glands and is more adherent. These variations affect the final nasal contour and profile after rhinoplasty.

The skin of the nose is separated from the underlying osteocartilaginous framework by four layers. These are the superficial fatty panniculus; the fibromuscular layer, a continuation of the facial superficial musculo-aponeurotic system (SMAS) ( Ch. 36 ); the deep fatty layer; and the periosteum or perichondrium.

Soft tissue areas of the nose

Four soft tissue areas of the nose lack cartilaginous support. They have been given numerous eponymous names and descriptions, but were reclassified by .

Paraseptal soft tissue area

The supratip area contains the paired lateral cartilages, which gradually separate from the septum to a level just above the septal angle. The amount of flare varies, and encloses a small paraseptal soft tissue triangle on each side of the septum.

Lateral soft tissue area

The lateral margin of the lateral cartilage, the piriform aperture and the cranial margin of the lateral crus of the major alar cartilage enclose a triangle containing loose fibroareolar tissue, the transverse portion of nasalis, and one or more small sesamoid cartilages.

Caudal lobular notch

The domal segment of the intermediate crus of the major alar cartilage has a small indentation. The apex of the nostril is a soft tissue triangle with little soft tissue separating the internal and external skin. Incisions in this area may cause unsightly scarring and deformity.

Alar soft tissue area

The lateral crus fails to extend to the lateral limit of the lobule, forming the fourth soft tissue area.

Bones and cartilage

Bony skeleton of the external nose

The piriform aperture has sharp edges. It is bounded below and laterally by the maxilla and above by the nasal bones ( Fig. 39.3 ). The lateral part of the inferior edge of the piriform aperture merges into its lateral wall, which is formed by the frontal process of the maxilla. It is bounded above by the nasal part of the frontal bone and superomedially by the lateral edge of the nasal bone.

Fig. 39.3, The bony and cartilaginous skeletons of the nose. A , The external nose, frontal view. B , The external nose, lateral view. C , An inferior view of the cartilages. D , The nasal cavity, medial wall. E , The nasal cavity, lateral wall (left side).

The paired nasal bones vary in thickness and width, which is of significance in planning osteotomies. They are thickest and widest at the nasofrontal suture, narrow at the nasofrontal angle before they widen, and become thinner 9–12 mm below the nasofrontal angle. They average 25 mm in length but this can vary widely. The perpendicular plate of the ethmoid bone (part of the bony nasal septum) articulates with the undersurface of the nasal bones and provides support to the dorsum of the nose. A midline bony spine deep to the fused nasal bone projects inwards to articulate with the perpendicular plate of the ethmoid and fuses with the fibrous tissue connecting the lateral nasal cartilages and cartilaginous septum. This is known as the keystone area and provides essential support to the nasal dorsum ( ).

Fractures of the nasal bones

The most common injury to the facial skeleton is a fracture of the nasal bones. In simple fractures, the break often occurs between the proximal thicker bone and the thinner bone distally. Displaced fractures require reduction to avoid cosmetic deformity. The terminal branch of the anterior ethmoidal nerve and its accompanying vessels are at risk when injuries involve the dorsum of the nose.

Cartilaginous skeleton of the external nose

The cartilaginous framework consists of the paired lateral and major cartilages and several minor alar nasal cartilages (see Fig. 39.3 ).

Lateral (superior/upper lateral) nasal cartilage

The lateral nasal cartilage is triangular, and its anterior margin is thicker than the posterior margin. The upper part fuses with the septal cartilage, but anteroinferiorly, it may be separated from it by a narrow fissure. The superior margin of the lateral nasal cartilage is attached to the nasal bone and frontal process of the maxilla, and the inferior margin is connected by fibrous tissue to the lateral crus of the major alar cartilage. Laterally, the cartilage is attached indirectly to the margins of the piriform aperture by loose fibroareolar connective tissue, which may also contain one or more small sesamoid cartilages. The angle formed between the caudal end of the lower lateral and the septum, the internal nasal valve, is usually between 10 and 15° and represents the narrowest cross-sectional area and the area of greatest airflow resistance. Structural abnormalities in this area are likely to produce symptomatic nasal obstruction.

Major alar (lower lateral) cartilage

The major alar cartilage is a highly complex, thin, flexible plate, which is integral to the nasal lobule. It lies below the upper lateral cartilage and curves acutely around the anterior part of its naris. The medial part, the narrow medial crus (septal process), is loosely connected by fibrous tissue to its contralateral counterpart and to the anteroinferior part of the septal cartilage. The intermediate crus forms the margin of the apex of the nostril. The domes give rise to the tip-defining points of the nose. The lateral crus lies lateral to the naris and runs superolat-erally away from the margin of the nasal ala. The upper border of the lateral crus of the major alar cartilage is attached by fibrous tissue to the lower border of the lateral nasal cartilage. Its lateral border is connected to the frontal process of the maxilla by a tough fibrous membrane containing three or four minor alar cartilages. The junction between the lateral crura of the major alar and lateral cartilages is variable; the two edges may form a ‘scroll’, with an outcurving of the lateral cartilage meeting an incurving of the major alar cartilage, in which case the lateral crus is then the more lateral at the junction. The lateral crus is shorter than the lateral margin of the naris; the most lateral part of the margin of the ala nasi is fibroadipose tissue covered by skin. In front, the angulations or ‘domes’ between the medial and lateral crurae of the major alar cartilages are separated by a notch palpable at the tip of the nose.

Alar cartilage morphology

The medial crus has two components, a footplate segment and a columellar segment, which angulate with each other in two planes; they diverge in the basal plane, and rotate upwards in the lateral plane. There is usually asymmetry in the pairs of medial crura.

The medial crus joins the intermediate crus at what is usually the most convex point of the columella, known as the columellar breakpoint.

The intermediate crus is also described in two components. The lobular segment is usually flared and forms the transition between the medial crus and the domal segment of the intermediate crus. The domal segment may be convex, producing an aesthetically pleasing tip; flat, giving a ‘boxy’ appearance; or convex, producing a ‘double-dome’. The domal or tip-defining points are usually formed by the most anterior projection of the domal segment. The amount of divergence of the domes, and the thickness of the overlying soft tissue envelope, determine the relative position of the tip-defining points. The dome projects up to 8–10 mm caudal, and 3–6 mm anterior, to the anterior septal angle, the difference between the two creating the supratip break-point. Disruption of this relationship with rhinoplasty, with loss of projection of the tip, may produce a ‘polybeak’ deformity.

Classically, transverse connective tissue fibres have been described binding the medial and intermediate crura; interdomal, intercrural and septocrural ligaments have been described. Cadaveric studies by disputed the presence of transverse fibres, and found that all connective tissue fibres run parallel to the cartilages. These findings notwithstanding, the fibrous connections along the length of the medial and intermediate crura form a single functional unit in the tip.

The large lateral crus determines the shape of the alar lateral wall. Medially, it is a continuation of the intermediate crus, while laterally it connects with accessory cartilages. It runs at the caudal edge of the alar rim in the anterior half, then moves cephalically, leaving a soft tissue area in the rim laterally. Typically, the longitudinal axis of the lateral crus forms an angle of 45° with the septum. More vertical, or cephalic, positioning results in a ‘parenthesis’ tip deformity.

The lateral crus may take a highly variable position, being either convex or concave, or a combination of both, in medial and lateral portions; asymmetry from side to side has been reported in over half of anatomical specimens.

A chain of lateral accessory cartilages with dense fibrous attachments connect to the lateral crus and the piriform aperture, and to the anterior nasal spine through connection in the floor of the nose.

Tip support

The inherent strength and shape of the cartilaginous framework, and its attachments to surrounding structures, provide support to the tip of the nose. Typically, ‘major’ and ‘minor’ tip support mechanisms are described.

Major tip support mechanisms

The major mechanisms supporting the tip are: the size, shape and strength of the major alar cartilages; the medial crural footplate attachment to the caudal part of the septum; the attachment of the caudal border of the lateral cartilages to the cephalic border of the major alar cartilages; and the cartilaginous dorsal septum.

Minor tip support mechanisms

The minor mechanisms supporting the tip are: the ligamentous sling spanning the domes of the lower lateral cartilages (i.e. the interdomal ligament); the sesamoid complex of major alar cartilages; the attachment of the major alar cartilages to the overlying skin/soft tissue envelope; the nasal spine; and the membranous septum.

Rhinoplasty approaches, either through an intercartilaginous incision between the lateral and the major alar cartilages (closed rhinoplasty), or through an incision caudal to the major alar cartilages and degloving the entire cartilaginous framework (open rhinoplasty), disrupt the tip support mechanisms; the integrity of these mechanisms must be restored during the procedure to prevent loss of tip support and subsequent tip ptosis.

Muscles

The nasal muscle group includes procerus, nasalis, dilator naris anterior, depressor septi and levator labii superioris alaeque nasi ( Fig. 39.4 ; see Figs 36.17 , 36.18 ). These muscles are involved in respiration and facial expression. Any or all of these muscles may be absent in cleft lip deformities with corresponding functional and aesthetic consequences.

Procerus

Procerus is a small pyramidal muscle that lies close to, and is often partially blended with, the medial side of the frontal part of occipitofrontalis. It arises from a fascial aponeurosis attached to the periosteum covering the lower part of the nasal bone, the perichondrium covering the upper part of the lateral nasal cartilage, and the aponeurosis of the transverse part of nasalis. It is inserted into the glabellar skin over the lower part of the forehead between the eyebrows.

Vascular supply

Procerus is supplied mainly by branches from the facial artery.

Innervation

Procerus is supplied by temporal and lower zygomatic branches from the facial nerve (a supply from the buccal branch has been described).

Actions

Procerus draws down the medial angle of the eyebrow and produces transverse wrinkles over the bridge of the nose. It is active in frowning and ‘concentration’, and helps to reduce the glare of bright sunlight. Not surprisingly, it is a common target in non-surgical facial rejuvenation techniques, using botulinum toxin.

Nasalis

Nasalis consists of transverse and alar components. The transverse part (compressor naris) is attached to the maxilla above and lateral to the incisive fossa, and lateral to the alar part. Its fibres pass upwards and medially, and expand into a thin aponeurosis that merges with its counterpart across the bridge of the nose, with the aponeuroses of procerus, and with fibres from levator labii superioris alaeque nasi. Fibres from the transverse part may also blend with the skin of the nasolabial and alar folds. The alar part (pars alaris or dilator naris posterior) is attached to the maxilla above the lateral incisor and canine, lateral to the bony attachment of depressor septi, and medial to the transverse part, with which it partly merges. Its fibres pass upwards and anteriorly, and are attached to the skin of the ala above the lateral crus of the lower lateral cartilage, and to the posterior part of the mobile septum. The pars alaris helps to produce the upper ridge of the philtrum.

Dilator naris anterior (also known as apicis nasi or the small dilator muscle of the nose) is a very small muscle attached to the upper lateral cartilage, the alar part of nasalis, the caudal margin of the lateral crus and the lateral alar crus. It encircles the naris and acts as a primary dilator of the nostril.

Vascular supply

Nasalis is supplied by branches from the facial artery and from the infraorbital branch of the maxillary artery.

Innervation

Nasalis is supplied by the buccal branch of the facial nerve. It may also be supplied by the zygomatic branch of the facial nerve.

Actions

The transverse part compresses the nasal aperture at the junction of the vestibule and the nasal cavity. The alar parts draw the alae and posterior part of the columella downwards and laterally, and so assist in widening the nares and in elongating the nose. They are active immediately before inspiration. Dilator naris anterior and the alar part of nasalis (dilator naris posterior) probably function to prevent collapse of the nasal valve during inspiration. Their electromyographic activity is directly proportional to ventilatory resistance and is modified by signals that travel from pulmonary mechano- and pressure receptors via afferent vagal pathways to the brainstem respiratory centre; the efferent limb of the reflex arc runs in the facial nerve.

Depressor septi

Depressor septi lies immediately deep to the mucous membrane of the upper lip. It is usually attached to the periosteum covering the maxilla above the central and lateral incisors and the anterior nasal spine, and to the fibres of orbicularis oris above the central incisor. Its fibres pass to the columella, the mobile part of the nasal septum and the base of the medial crus of the nasal cartilage. A few muscle slips may pass between the medial crura into the nasal tip. Depressor septi may be absent or rudimentary.

Vascular supply

Depressor septi is supplied by the superior labial branch of the facial artery.

Innervation

Depressor septi is innervated by the buccal branch, and sometimes by the zygomatic branch, of the facial nerve.

Actions

Depressor septi pulls the columella, the tip of the nose and the nasal septum downwards. It tenses the nasal septum at the start of nasal inspiration and, with the alar part of nasalis, widens the nasal aperture, as well as causing the nose to ‘dip’ when some people smile.

Levator labii superioris alaeque nasi

Levator labii superioris alaeque nasi arises from the upper part of the frontal process of the maxilla and, passing obliquely downwards and laterally, divides into medial and lateral slips. The medial slip blends into the perichondrium of the lateral crus of the major alar cartilage of the nose and the skin over it. The lateral slip is prolonged into the lateral part of the upper lip, where it blends with levator labii superioris and orbicularis oris. Superficial fibres of the lateral slip curve laterally across the front of levator labii superioris and attach along the floor of the dermis at the upper part of the nasolabial furrow and ridge.

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Nose

External Nose

Facial and nasal proportions

Skin and soft tissue

Soft tissue areas of the nose

Paraseptal soft tissue area

Lateral soft tissue area

Caudal lobular notch

Alar soft tissue area

Bones and cartilage

Bony skeleton of the external nose

Fractures of the nasal bones

Cartilaginous skeleton of the external nose

Lateral (superior/upper lateral) nasal cartilage

Major alar (lower lateral) cartilage

Alar cartilage morphology

Tip support

Major tip support mechanisms

Minor tip support mechanisms

Muscles

Procerus

Vascular supply

Innervation

Actions

Nasalis

Vascular supply

Innervation

Actions

Depressor septi

Vascular supply

Innervation

Actions

Levator labii superioris alaeque nasi

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