thomas von arx1 2 extraoral anatomy in cbct - michael m ... · fourth concha suprema (santorini’s...

SWISS DENTAL JOURNAL SSO VOL 129 10 P 2019

RESEARCH AND SCIENCE804804

SUMMARY

Cone beam computed tomography has become a

widely used imaging technique for dental indica-

tions. Depending on the selected size of the field

of view, anatomical structures outside the den-

tomaxillary complex become visible. As a conse-

quence, the clinician must be able to interpret

also those anatomical regions. In this article, the

anatomy of the nasoethmoidal region is present-

ed based on a literature review. The nose is char-

acterized by the nasal septum and the superior,

middle, and inferior conchae. The turbinates may

be pneumatized (concha bullosa), mainly the

middle concha. The ethmoid bone has a complex

morphology (ethmoid labyrinths) and contributes

with its perpendicular plate to the nasal septum.

Other structures of the septum include the vomer

and the septal cartilage. The nasal meatuses sta-

bilize the airflow and direct the inhaled air to the

nasopharynx via the choanae. The middle nasal

meatus, which is also a part of the so called os-

tiomeatal complex, serves as the major drainage

area (semilunar hiatus) of the paranasal sinuses,

i.e., maxillary sinus, anterior ethmoid cells, and

frontal sinus. Posterior ethmoid cells empty into

the superior meatus and the sphenoid sinus

drains into the sphenoethmoidal recess, located

above the superior concha. The nasolacrimal duct

that is running along the middle portion of the

lateral nasal wall opens into the inferior nasal

meatus.

KEYWORDSAnatomy CBCT Nasal cavity Ethmoid bone

Extraoral anatomy in CBCT - a literature review

Part 1: Nasoethmoidal region

Thomas von Arx1

Scott Lozanoff2

Michael M. Bornstein3

1 Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, Switzerland

2 Department of Anatomy, Biochemistry and Physiology, John A. Burns School of Medi-cine, University of Hawaii, Honolulu, USA

3 Oral and Maxillofacial Radiol-ogy, Applied Oral Sciences, Faculty of Dentistry, The Uni-versity of Hong Kong, Prince Philip Dental Hospital, Hong Kong SAR, China

CORRESPONDENCEProf. Dr. Thomas von ArxKlinik für Oralchirurgie und Stomatologie Zahnmedizinische Kliniken der Universität Bern Freiburgstrasse 7 CH-3010 Bern Tel. +41 31 632 25 66 Fax +41 31 632 25 03 E-mail: [email protected]

SWISS DENTAL JOURNAL SSO 129: 804–815 (2019)Accepted for publication: 10 December 2018

804-815_T1-1_vonarx_EDF.indd 804 01.10.19 11:09


805RESEARCH AND SCIENCE

IntroductionKnowledge of anatomical structures and their spatial relation-ships is critical in medicine and dentistry for diagnosis and treatment planning (von Arx & Lozanoff 2017). Current medical and dental curricula teach anatomy at the very beginning of training in the undergraduate phase. As a consequence, ana-tomical knowledge may be gradually or selectively lost over the years of clinical work.

Over the course of the last two decades, cone beam computed tomography (CBCT) has become the standard of three-dimen-sional imaging in dentistry. Main indications for using CBCT in the various disciplines of dental medicine have recently been established by the Swiss Association of Dentomaxillofacial Ra-diology (Dula et al. 2014, 2015). Maxillofacial surgery, ophthal-mology and otorhinolaryngology are other specialties with an increased interest in CBCT (Bremke et al. 2010; Tschopp et al. 2014; Lata et al. 2018).

Nevertheless, CBCT has been reported to have also some shortcomings in comparison with advanced medical imaging procedures such as multi-slice computed tomography (msCT) or magnetic resonance imaging (MRI). This especially applies to the lack of a diagnostically distinct soft tissue contrast, narrow-ing down the diagnostic potential of CBCT imaging and limiting potential applications for soft tissue integration in presurgical planning (Jacobs et al. 2018). Furthermore, Hounsfield units do not apply to CBCT images, which makes it impossible to com-pare grey values among or within patients over time. This lack of standardized grey value distribution narrows down the use of CBCT for bone density analysis and follow-up of bone density changes (Pauwels et al. 2015). Compared to Hounsfield units for medical CT, the reliability of CBCT-based jaw bone density as-sessment has been found unreliable over time and with signifi-cant variations influenced by CBCT devices, imaging parame-ters and head positioning.

Currently, the vast majority of case-based CBCT imaging in-cludes dental and maxillofacial indications (de Vos et al. 2009).However, in larger fields of view (FOVs ≥ 10 × 10 cm), anatomical structures outside the oral cavity become visible (Bornstein et al. 2014). The clinician evaluating CBCT scans must assess and understand the relevant anatomy, but is also responsible for recognizing abnormalities within the complete image data set and beyond the region of interest (Carter et al. 2008; Horner et al. 2009).

The objective of this series of publications entitled “Extraoral anatomy in CBCT” is to provide a literature update with detailed information about anatomical structures usually seen on larger FOVs that may be less easily identified by the dental practi-tioner. The clinician remains responsible for incidental findings in the CBCT image stack. This series of reviews is intended to refresh the dental practitioner’s anatomical knowledge base facilitating accurate assessment and ultimately improving the health of the patient. The first topic in this series addresses the nasoethmoidal region.

NoseThe nose includes the visible outer structures, such as the nasal wings and the nasal dorsum, and the nasal cavities internally. The skeletal framework of the nose is osseous (upper part) as well as cartilaginous (lower and lateral parts) (Fig. 1 and 2) (von Arx et al. 2018a). The two small and flat nasal bones form the central part of the nasal root that is supplemented laterally by the frontal processes of the os maxillae. Several cartilages contribute to the

Fig. 1 Graphic illustration of the skeletal framework of the nose and adjacent structures 1 = upper lateral cartilage; 2 = superior margin of septal cartilage; 3 = lower lateral (alar) cartilage; 4 = nasal bone; 5 = frontal process of os maxillae; 6 = lacrimal bone; 7 = cavity for lacrimal sac; 8 = lamina orbitalis (papyracea) of ethmoid bone

Fig. 2 Lateral view of dissected cadaveric nasal skeleton (right side) 1 = nasal bone; 2 = frontal process of os maxillae; 3 = upper lateral cartilage; 4 = lower lateral (alar) cartilage; 5 = nostril; 6 = infraorbital foramen with neurovascular bundle

804-815_T1-1_vonarx_EDF.indd 805 01.10.19 11:09


806 RESEARCH AND SCIENCE

lower portion of the nose. The central nasal ridge is formed by the superior margin of the septal cartilage. The nasal wings con-sist of the triangular-shaped lateral cartilages, also called upper lateral cartilages. These cartilages project superiorly below the nasal bones and attach through dense connective tissue (Ogle et al. 2012). The edges of the nasal orifices, or nostrils, and the colu-mella are formed by the scroll-shaped alar cartilages (also called lower lateral cartilages) that form the curved external openings of the nose (Hafezi et al. 2010). Each lower lateral cartilage has a medial and a lateral crus that shape the nasal tip and maintain the patency of the nostrils (Ogle et al. 2012). Additional small cartilages contribute variably to the nasal wings and include the minor alar cartilages or sesamoid cartilages.

Nasal cavityThe nasal cavity is a bilateral structure located in the midface (Fig. 3–12). Inferiorly it is bordered by the hard palate while the roof of the nasal cavity is formed by the cribriform plate of the ethmoid bone. A midline septum oriented in the sagittal plane divides the nasal cavity into two bilateral cavities. Anteriorly, the nasal vestibules positioned outside the osseous part of the nose serve as the communication from the nostrils to the proper nasal cavities. The nasal cavities have anterior (ventral) open-ings, i.e. the nostrils (or nares), and posterior (dorsal) openings, i.e. the choanae. The latter represent the gateway to the naso-pharynx.

Major functions of the nose include respiration and olfaction. Hairs (vibrissae) located in the vestibule have a cleaning func-tion, whereas the nasal mucosa warms and humidifies the inhaled air. The nasal conchae enlarge the functional mucosa of the nasal cavities. Olfactory cells are mainly located on the upper conchae.

The three nasal conchae, superior, middle, and inferior, also termed nasal turbinates (“turbid” from Latin to disturb), exhibit a scrolled cross-section in the coronal plane with the free end directed laterally. Occasionally, a paradoxical curvature, mainly of the middle turbinate, is observed, i.e., the turbinate is scrolled in a medial direction (Sava et al. 2018). The inferior concha typi-cally is the largest while the superior is the smallest. Rarely, a fourth concha suprema (Santorini’s concha) is described that is located at the posterosuperior aspect of the lateral nasal wall close to the lateral margin of the ostium of the sphenoid sinus (Sava et al. 2018). The term “concha bullosa” generally refers to the pneumatization of the middle turbinate. However, pneu-matization may also occur of the superior and inferior turbinates (Ila et al. 2018). In fact, the presence of a “void” within the con-cha(e) is an optical illusion on 2D pictures, since the “pneuma-tized” cavity always presents with a connection to the corre-sponding nasal meatus.

The three conchae divide the nasal cavities into four spaces, i.e. from top to bottom, sphenoethmoidal recess, superior nasal meatus, middle nasal meatus, and inferior nasal meatus. The middle meatus, is the most complex and serves as the major drainage area of the paranasal sinuses (Ogle et al. 2012). The four air channels on each side divide and compartmentalize airflow. Furthermore, they increase and stabilize airflow pres-sure and velocity while also directing the air to the nasopharynx via the choanae (Doorly et al. 2008).

The ostiomeatal complex is the functional unit of the anterior ethmoid including the maxillary ostium, the middle meatus, the hiatus semilunaris, the uncinate process, and the bulla eth-moidalis (Gibelli et al. 2018). The ostiomeatal complex is con-

Fig. 3 Graphic illustration of the left nasal cavity and adjacent structures 1 = frontal sinus; 2 = ethmoid cells (ethmoid sinus); 3 = sphenoid sinus; 4 = sphenoethmoidal recess with opening of sphenoid sinus; 5 = upper nasal meatus with opening of posterior ethmoid cells; 6 = location of underlying sphenopalatine foramen; 7 = partially resected middle concha; 8 = bulla ethmoidalis; 9 = opening of frontal sinus in upper part of semilunar hiatus; 10 = opening of anterior ethmoid cells in middle part of semilunar hiatus; 11 = opening of maxillary sinus (ostium maxillare) in lower part of semilunar hiatus; 12 = uncinate process of ethmoid bone; 13 = middle nasal meatus; 14 = partially resected inferior concha; 15 = opening of nasolacrimal duct; 16 = inferior nasal meatus; 17 = nasal opening of nasopalatine canal

Fig. 4 Medial view of left nasal cavity (paramedian section of dry skull) 1 = frontal sinus; 2 = anterior cranial fossa; 3 = nasal bone; 4 = os maxillae; 5 = superior concha; 6 = middle concha; 7 = inferior concha; 8 = sphenoeth-moidal recess; 9 = maxillary ostium; 10 = sphenopalatine foramen; 11 = sphe-noid sinus; 12 = hypophyseal fossa; 13 = nasopalatine canal; *** = semilunar hiatus

804-815_T1-1_vonarx_EDF.indd 806 01.10.19 11:09



sidered a critical area for paranasal ventilation and drainage since it is located at the crossroads between the nasal cavities and the paranasal sinuses (Khojastepour et al. 2015).

The paranasal sinuses, i.e., frontal sinus, sphenoid sinus, ethmoid cells, and maxillary sinus, drain into the meatuses via distinguished openings or ostia. The largest gateway is the maxillary ostium serving as the communication between the maxillary sinus and the middle meatus. The maxillary ostium is located in the lower part of the semilunar hiatus, a broad and curved opening within the lateral nasal wall located between the inferior and middle turbinates. Also the frontal sinus drains into the middle meatus with its ostium located in the upper part of the semilunar hiatus. Multiple small openings serve for drain-age of the ethmoid air cells (see below).

A structure not related to the paranasal sinuses but still drain-ing into the nasal cavity is the nasolacrimal duct. It originates from the lacrimal sac at the anteroinferior corner of the orbital cavity. The nasolacrimal duct terminates in the anterior third of the inferior nasal meatus (Wilhelm et al. 2009; Tschopp et al. 2014; Bornstein et al. 2017a). The bony nasolacrimal canal is usu-ally inclined posteriorly and laterally toward the maxillary first molar (Ali et al. 2014). In a study with 15 cadaveric human half heads, the mean length of the nasolacrimal duct was 21.9 mm and its intranasal orifice was located on average 13.7 mm above the nasal floor (Tatlisumak et al. 2010).

Nasal floorThe nasal floor is formed by the same osseous structures that contribute to the hard palate, i.e., the palatine processes of the ox maxillae (anteriorly) and the horizontal plates of the palatine bones (posteriorly). Ventral and dorsal midline bony projections at the level of the nasal floor include the anterior and posterior nasal spines. In a study of 50 embalmed cadaver hemiheads, the mean distance from the anterior to the posterior nasal spines was 5.6 ± 0.3 cm (Donmez et al. 2005). The nasal crest is located

above the fusion zone of the palatal processes of the os maxillae and the os palatinum. Prominent, funnel-shaped bilateral open-ings are located along the anterior nasal crest and serve as the nasal openings of the nasopalatine canal.

Fig. 5 Medial view of left nasal cavity (paramedian cadaveric section) 1 = frontal sinus; 2 = infundibulum of frontal recess; 3 = nasal bone; 4 = nasal septum; 5 = anterior ethmoid cells; 6 = posterior ethmoid cells; 7 = sphenoid sinus; 8 = bulla ethmoidalis; 9 = middle concha; 10 = inferior concha; *** = semilunar hiatus

Fig. 6 CBCT of a 20-year-old male (original FOV 10 × 10 cm) with coronal (A), sagittal (B) and axial (C) views 1 = Agger nasi cell; 2 = frontal sinus; 3 = middle concha (pneumatized on left side); 4 = inferior concha; 5 = nasolacrimal duct; 6 = maxillary sinus; 7 = per-pendicular plate of ethmoid bone; 8 = anterior ethmoid cells; 9 = posterior ethmoid cells; 10 = sphenoid sinus; *** = semilunar hiatus

804-815_T1-1_vonarx_EDF.indd 807 01.10.19 11:09



Fig. 7 CBCT of a 34-year-old female (original FOV 10 × 10 cm) with coro-nal (A), sagittal (B) and axial (C) views 1 = nasolacrimal duct; 2 = inferior meatus; 3 = inferior concha; 4 = maxillary sinus; 5 = septal cartilage; 6 = nasal crest; 7 = perpendicular plate of ethmoid bone; 8 = anterior ethmoid cells; 9 = posterior ethmoid cells; 10 = sphenoid sinus; 11 = frontal process of os maxillae; 12 = middle concha

Fig. 8 CBCT of a 66-year-old male (original FOV 10 × 10 cm) with coronal (A), sagittal (B) and axial (C) views 1 = inferior concha; 2 = inferior meatus; 3 = middle concha; 4 = middle meatus; 5 = superior concha; 6 = superior meatus; 7 = sphenoethmoidal recess; 8 = perpendicular plate of ethmoid bone; 9 = vomer; 10 = nasal crest; 11 = maxillary sinus; 12 = posterior ethmoid cells (*Onodi cell); 13 = anterior ethmoid cells; 14 = inferior orbital fissure; 15 = optic canal; 16 = superior orbital fissure; 17 = sphenoid sinus. Note that both maxillary sinuses demonstrate spherical mucosal thickenings on the floor (Fig. A).

804-815_T1-1_vonarx_EDF.indd 808 01.10.19 11:09



Fig. 9 CBCT of a 20-year-old female (original FOV 10 × 10 cm) with coro-nal (A), sagittal (B) and axial (C) views 1 = “sinus septi nasi”; 2 = sphenoid sinus (*extension of sphenoid sinus into nasal septum); 3 = maxillary sinus; 4 = vomer; 5 = perpendicular plate of ethmoid bone; 6 = nasopalatine canal; 7 = superior concha; 8 = middle concha; 9 = inferior concha; 10 = nasolacrimal duct

Fig. 10 CBCT of a 67-year-old female (original FOV 10 × 10 cm) with coro-nal (A), sagittal (B) and axial (C) views 1 = nasolacrimal duct; 2 = inferior orbital fissure; 3 = infraorbital canal; 4 = middle concha (extensively pneumatized); 5 = inferior concha; 6 = maxil-lary sinus; 7 = sphenoid sinus; 8 = hypophyseal fossa

804-815_T1-1_vonarx_EDF.indd 809 01.10.19 11:09



Lateral nasal wallThe lateral walls of the proper nasal cavities consist of the os maxillae (anterior as well as inferior parts), the vertical plate of the palatine bone (posterior part), the nasal bone (anterosupe-

rior part), and the ethmoid bone (superior part). Furthermore, the small lacrimal bone also contributes to the lateral nasal wall roughly in the center portion.

Larger openings in the lateral wall include the semilunar hia-tus and the sphenopalatine foramen. The sphenopalatine fora-men is either located at the posterior transition of the superior and middle meatus or posteriorly within the superior meatus (El-Shaarawy & Hassan 2018; Eördögh et al. 2018). The spheno-palatine foramen serves as the communication between the pterygopalatine fossa and the nasal cavity (von Arx & Lozanoff 2017). Two superior processes of the vertical plate of the palatine bone contacting the sphenoid bone form the sphenopalatine foramen (Morton & Khan 1991). The mean diameter of the sphe-nopalatine foramen has been reported to be 5.3 mm (Hwang et al. 2011). According to a skull study by Prades et al. (2008), the sphenopalatine foramen is positioned on average 13 mm above the horizontal lamina of the inferior concha and 18.3 mm above the horizontal plate of the palatine bone.

The semilunar hiatus is located approximately in the central area of the lateral nasal wall at the level of the middle nasal me-atus and laterally to the middle concha. The semilunar hiatus has a horizontal inferior (posterior) and a vertical superior (an-terior) component (Stammberger & Kennedy 1995), thus it shows an ascending crescent shape but may exhibit great morphologic variability (Dahlstrom & Olinger 2014). The latter authors quan-tified the width and length of the semilunar hiatus in 97 hemi-sected embalmed human heads. The mean width at the supero-anterior border was 1.7 mm and at the inferoposterior border 4.7 mm, whereas the mean length was 26 mm. The following structures drain into the semilunar hiatus: the frontal sinus into the superior aspect, the anterior ethmoid cells into the middle aspect, and the maxillary sinus via the maxillary ostium into the inferior aspect of the semilunar hiatus.

Areas of the lateral nasal wall in which no bone exists are called “nasal fontanelles” (Stammberger & Kennedy 1995). The mucosa of the maxillary sinus and of the middle nasal meatus are only separated by a fibrous layer. The nasal fontanelles are

Fig. 11 CBCT of a 27-year-old female (original FOV 20 × 17 cm) with coro-nal (A), sagittal (B) and axial (C) views 1 = infraorbital canal; 2 = maxillary sinus; 3 = middle concha (pneumatized); 4 = inferior concha; 5 = pterygopalatine fossa; 6 = uncinate process; 7 = os-tium maxillare; 8 = ethmoid cells; 9 = nasolacrimal duct; 10 = sphenoid sinus; 11 = frontal sinus; * = large Haller cell. It appears that the patient has had maxillary sinus surgery on the right side (° Fig. A).

Fig. 12 Anterolateral view of medial wall of left orbital cavity with trans-illuminated ethmoidal cells 1 = optic canal; 2 = superior orbital fissure; 3 = inferior orbital fissure; 4 = orbital floor; 5 = nasal boe; 6 = frontal process of os maxillae; *** = ethmoid cells

804-815_T1-1_vonarx_EDF.indd 810 01.10.19 11:09



usually located above the insertion of the inferior concha with distinction of an anterior and a posterior fontanelle.

Inferior conchaThe inferior nasal turbinate is considered an independent bone that articulates with the maxilla, palatine, ethmoid and lacrimal bones. It is the largest of all three conchae and extends along the entire length of the nasal cavity (Ogle et al. 2012). The infe-rior nasal concha displays a complex morphology with long processes including the ethmoidal, lacrimal and maxillary ar-ticulating with adjacent bones while also forming a portion of the medial wall of the maxillary sinus as well as the nasolacri-mal duct. Pneumatization of the inferior concha is a rare con-dition with a reported frequency of 1% (Shpilberg et al. 2015; Koo et al. 2017).

Nasal septumThe nasal septum is a mixed osseous and cartilaginous structure and it is composed of five parts (Fig. 13) (Ogle et al. 2012):– Perpendicular plate of ethmoid bone– Vomer– Septal cartilage– Nasal crest of maxillary bones– Nasal crest of palatine bones

The vomer and the ethmoid bone contribute to the osseous, posterior part of the septum. The anterior part of the septum comprises the septal cartilage that articulates with the nasal crest.

Surface area mapping of the nasal septum using CT in 100 Cau-casian patients revealed the following mean figures for males and females, respectively: vomer 894 mm2 and 741 mm2, perpendic-ular plate of ethmoid bone 1,244 mm2 and 1,066 mm2, septal car-tilage 1,148 mm2 and 981 mm2 (Daultrey et al. 2018). In total, the surface areas of the nasal septum amounted to approximately

33 cm2 in males and to 27 cm2 in females. In a similar study con-ducted in 168 Koreans, the following mean surface areas were reported for males and females: vomer 964 mm2 and 822 mm2, perpendicular plate of ethmoid bone 1,084 mm2 and 975 mm2, septal cartilage 768 mm2 and 713 mm2 (Kim et al. 2010b). The cal-culated mean total surface areas were 28 cm2 in males and 25 cm2 in females.

According to Hur et al. (2016), the nasal crest contributes 5.6% to the surface area of the nasal septum. In contrast, the perpendicular plate of the ethmoid bone represents 43.0%, the vomer 25.8% and the septal cartilage 25.6% of the septal sur-face area. The same authors also reported in 74.3% of the evalu-ated specimens the presence of an elevated premaxillary wing that extended from the os maxillae upwards between the septal cartilage and the vomer.

Nasal septal deviation is a common finding with frequencies ranging from 14 to 80% (Koo et al. 2017). Nasal septal deviation is defined as any bending of the septal contour in the coronal or axial planes (Shpilberg et al. 2015). The deviation of the septum occurs usually at the union of the vomer either with the perpen-dicular plate of the ethmoid bone or with the septal cartilage, respectively (Hur et al. 2016). The presence of a nasal septal de-viation is often associated with the occurrence of a unilateral concha bullosa (middle turbinate), or a prominent bulging con-cha in the case of bilateral conchae bullosae (Stallman et al. 2004). As a result, the deformed septum shows a convexity to the opposite side with regard to the widened middle concha, but the air channel between the deviated septum and the en-larged concha is preserved.

Septal cartilageThe septal cartilage, quadrangular or triangular in shape, extends anteriorly to the anterior nasal spine to which it is attached via loose connective tissue fibers (chondrospinal junc-tion), thus allowing some mobility (Hafkamp et al. 1999). Some-times, the septal cartilage shows a posterior (sphenoidal) process projecting between the vomer and the perpendicular plate of the ethmoid bone (Hur et al. 2016). This sphenoidal process is con-sidered a remnant tail of the septal cartilage resulting from de-layed ossification of the nasal septum (Kim et al. 2012). The mean length of the posterior (sphenoidal) process in patients with a deviated nasal septum was 26.1 ± 5.3 mm versus 12.0 ± 2.4 mm in controls (Kim et al. 2010a). A long posterior (sphenoidal) process appears to contribute to exacerbation of septal deviation (Kim et al. 2012).

Hwang et al. (2010) assessed the size and thickness of the sep-tal cartilage in 15 Korean cadavers. They reported a mean length and height of 3.31 ± 0.53 cm and 2.99 ± 0.47 cm. The thickness of the septal cartilage showed great variability (0.7–3.0 mm) depending on the site of measurement. Generally, the greatest thickness was observed along the septal base. The septal carti-lage may show a bulge in its central area, called the nasal septal body or septal turbinate (Elwany et al. 2009). The septal body is usually located superior to the inferior concha and anterior to the middle concha.

VomerThe vomer forms the inferior part of the bony septum, but ex-tends posteriorly up to the body of the sphenoid bone. Occa-sionally, bilateral cavities (“fetal remnants”) are observed en-doscopically at the anterior bottom of the vomer close to the nasal openings of the nasopalatine canal (Trotier 2011). The

Fig. 13 Graphic illustration of the nasal septum (right side) and adjacent structures 1 = perpendicular plate of ethmoid bone; 1a = cribriform plate of ethmoid bone; 2 = septal cartilage; 2a = posterior (sphenoidal) process of septal carti-lage; 3 = vomer; 3a = vomeronasal cavity; 4 = nasal crest of maxillary bone; 5 = nasal crest of palatine bone; 6 = anterior nasal spine; 7 = nasopalatine (incisive) canal; 8 = medial plate of pterygoid process of sphenoid bone; 9 = sphenoid sinus; 10 = frontal sinus; 11 = nasal bone

804-815_T1-1_vonarx_EDF.indd 811 01.10.19 11:09



vomeronasal cavities contain the vomeronasal organs (VNO) during fetal development, but eventually, the VNO regress in the neonate (von Arx et al. 2018b).

Ethmoid boneThe singular ethmoid bone, located between the orbital cavi-ties, contributes to the upper half of the nasal skeleton. The ethmoid bone has a complex morphology with multiple bony plates, air cells (ethmoid labyrinths) and perforations. The eth-moid bone consists of five distinct components (Ogle et al. 2012):– Crista galli– Cribriform plate– Perpendicular plate– Bilateral ethmoid labyrinths

The crista galli is not a part of the nasal cavity but rather of the anterior cranial fossa. The perforated cribriform plate of the ethmoid bone forms the roof of the nasal cavities. The perfora-tions within the cribriform plate serve for passage of the olfac-tory nerve axons (cranial nerve II) from the olfactory cells to the brain. The size of the cribriform plate is as follows: length 20 mm, width 5 mm, and thickness (height) 2 mm (Ogle et al. 2012).

The centrally located perpendicular plate of the ethmoid bone (PPE) forms the upper portion of the nasal septum. Superiorly, the perpendicular plate is continuous with the cribriform plate. Mladina et al. (2017) concluded that compact bone is not con-stant since they found some degree of pneumatization in 34.4% of the PPE examined. This feature is referred to as “sinus septi nasi”. Hypothetically, this cavity formation within the nasal septum could be associated with extensions from the frontal or sphenoid sinuses into the PPE (Mladina et al. 2017).

The middle and superior turbinates are components of the ethmoid bone. The superior concha is located in the posterior third of the nasal cavity, with its anterior and highest portion opposite the medial canthal tendon (Ogle et al. 2012). The con-cha bullosa, i.e., the pneumatized middle nasal turbinate, is considered a normal and asymptomatic variant with reported frequencies of 13 to 53% (Koo et al. (2017). Pneumatization of the superior turbinate has also often been described with prev-alences ranging from 26 to 57% (Shpilberg et al. 2015). Ila et al. (2018) evaluated CT scans of 1,000 patients and reported pneumatization of the superior concha in 14.9%. Of those patients, 60.4% also presented pneumatization of the middle concha. A study by Koo et al. (2017) of 594 CT scans reported a frequency of superior and middle turbinate pneumatization of 38.7% and 53.7%, respectively.

The ethmoid bulla is a protuberance lateral to the middle meatus and transmits drainage accordingly. The uncinate pro-cess of the ethmoid bone projects inferolaterally, contributes to the lower border of the semilunar hiatus, and may contact the inferior concha. Superiorly, the uncinate process may attach to the lamina papyracea, the skull base, or the middle turbinate (Cheng et al. 2017). Occasionally, pneumatization of the unci-nate process (uncinate bulla) has been reported (Bolger et al. 1990; Koo et al. 2017).

Ethmoid labyrinths housing multiple air cells (ethmoid sinus) are located immediately medial to the medial orbital walls (Fig. 12). The most lateral parts of the ethmoid bone are the thin laminae orbitales (laminae papyraceae) that contribute to the medial walls of the orbital cavities. The basal lamina of

the middle turbinate divides the ethmoid cells into anterior and posterior divisons (Ogle et al. 2012). Many authors traditionally describe a middle ethmoid air cell creating the projection of the ethmoid bulla extending into the middle meatus (Perez-Pinaz 2000; Drake et al. 2015). However, currently accepted guide-lines for terminology of the paranasal sinuses indicate that the expressions “middle ethmoid” and “middle ethmoid cells” should not be used, because in terms of anatomy, physiology, or function, no structure represents the middle of the ethmoid complex (Stammberger & Kennedy 1995).

The ethmoid sinus is highly variable in form and structure as well as in the quantity of air cells (Zhang et al. 2007; Liu et al. 2018). Typically, seven smaller anterior cells and four larger posterior cells are present (Ogle et al. 2012). Anterior ethmoid air cells drain into the middle meatus whereas posterior eth-moid cells drain into the upper meatus and into the spheno-ethmoidal recess, respectively. Anatomical variants of the eth-moid air cells have been reported extensively (Wormald 2003; Stallman et al. 2004; Shpilberg et al. 2015; Cheng et al. 2017; Chmielik & Chmielik 2017; Liu et al. 2018) and include:– Agger nasi cell (occurrence rate 3–100%) (agger in Latin

means “mound”): defined as the most anteriorly placed frontal ethmoid cell that is located anterolateral and inferior to the frontal recess (the latter refers to the tubular space connecting the frontal sinus to the middle nasal meatus) (Fig. 6). According to Ogle et al. (2012), Agger nasi cells lay below the lacrimal sac from which they are separated by only a very thin layer of bone.

– Haller’s cell (occurrence rate 2–45%) (named after Albrecht von Haller, Swiss physician and anatomist, 1708–1777): infraorbital ethmoid cell located below the medial orbital floor and above the maxillary ostium (Fig. 11). According to Caversaccio et al. (2011), Haller’s cell should be defined as an anterior ethmoid cell, localized in the infraorbital region, hollowing out the maxillary bone and originating from the ethmoid labyrinth. It is the most inferior ethmoid cell that is located infraorbitally nearest to the ostium of the maxillary sinus.

– Onodi cell (occurrence rate 3–51%) (named after Adolf Onodi, Hungarian rhinolaryngologist, 1857–1919): most posterior ethmoid cell extending superiorly and laterally towards the sphenoid sinus (Fig. 8). Onodi cells may show an intimate relationship to the optic canal. Onodi cells are also known as sphenoethmoid air cells.

– Ethmomaxillary sinus (occurrence rate 0.7–7%): posterior eth-moid cell expanding toward or even entering the maxillary sinus with drainage to the superior nasal meatus.

DiscussionThis literature review presents an update of the clinical and radiological anatomy of the nasoethmoidal region. The latter includes the nasal cavities and the ethmoid bone. The ethmoid bone is a cuboidal structure that is located medial to the orbits above the nasal cavities and immediately inferior to the ante-rior cranial fossa. The nasal cavities are separated by a midline septum and contain each three nasal conchae (turbinates). A critical component of the nasoethmoidal region is the ostio-meatal complex. Disturbance of (para)nasal ventilation and drainage via the ostiomeatal complex may result in pansinus-itis.

The prescribing clinician, taking and/or viewing CBCT imag-es is challenged with interpreting the entire CBCT volume. The

804-815_T1-1_vonarx_EDF.indd 812 01.10.19 11:09



anatomy of the nasal cavity is complex, in particular the eth-moid bone, and possess great variability with regard to form and structure. Basically, the nose is one of two gateways for air to enter the body when breathing (the other being the oral cavity). Olfaction is another major function of the nose. The cribriform plate of the ethmoid bone has multiple openings for olfactory nerve axons to reach the olfactory bulbs in the ante-rior cranial fossa.

With regard to CBCT imaging, the nasal floor, the inferior and middle conchae and the lower aspects of the nasal septum are frequently observed on CBCT scans of the maxilla. Larger FOVs (≥ 10 × 10 cm), especially when used for diagnosis and treatment planning of implant placement in the posterior maxilla or the use of sinus floor elevation procedures, will also depict the complex ethmoid bone with its multiple air cells and anatomical variants (Bornstein et al. 2017b; Jacobs et al. 2018).

Understanding the complex anatomy and anatomical varia-tions of the nasoethmoidal region is crucial for radiologic inter-pretation and diagnosis, especially from a clinical point of view (Gibelli et al. 2018). The precision and quality of current CBCT imaging greatly support the clinician in the assessment of these important anatomical structures, and to rule out (para)nasal pathology.

AcknowledgementsThe authors thank Bernadette Rawyler, medical illustrator, and Ines Badertscher, media designer, School of Dental Medi-cine, University of Bern, Switzerland, for the illustrations. The authors acknowledge the generous donation of the anatomical materials by anonymous individuals in the Willed Body Pro-gram, University of Hawaii John A. Burns School of Medicine, Honolulu, USA.

We also acknowledge Dr. Andy Wai Kan Yeung, Oral and Maxillofacial Radiology, Applied Oral Sciences, Faculty of Den-tistry, The University of Hong Kong, Prince Philip Dental Hos-pital, Hong Kong, China, for providing some of the CBCT imag-es used in this study. Furthermore, we thank Dr. Odette Engel Brügger, School of Dental Medicine, University of Bern, Swit-zerland, for the French translation of the summary.

Conflict of interestThe authors declare that there are no conflicts of interest re-lated to this review.

ZusammenfassungDie digitale Volumentomografie (DVT) wird heute in der zahn-medizinischen Diagnostik immer häufiger eingesetzt. Je nach Grösse des gewählten DVT-Fensters werden auch anatomische Strukturen ausserhalb des dentomaxillären Komplexes abgebil-det. Um auch diese Strukturen richtig interpretieren zu kön-nen, muss der Kliniker entsprechende anatomische Kenntnisse haben. In dieser ersten von vier Arbeiten wird die Anatomie der nasoethmoidalen Region dargestellt und anhand der aktuellen Literatur diskutiert.

Die Nase besteht grundsätzlich aus den äusseren, sichtbaren Strukturen wie Nasenflügeln und Nasenrücken wie auch aus inneren Strukturen, den Nasenhöhlen. Das Nasengerüst besteht im oberen Teil aus Knochen (Os nasale sowie Processus frontalisdes Os maxillae) und im unteren Teil aus mehreren Knorpeln (Cartilagines laterales und Cartilagines alares). Das Vestibulum der Nase verbindet die äusseren Öffnungen der Nase (Nares) mit der

eigentlichen Nasenhöhle (Cavum nasi). Letztere wird durch das median und sagittal ausgerichtete Nasenseptum in zwei Kavi-täten unterteilt.

Das Septum nasi (Nasenscheidewand) ist aus fünf Teilen zu-sammengesetzt: Lamina perpendicularis des Ethmoid, Vomer,Knorpelseptum, sowie Cresta nasalis des Os maxillae und des Os palatinum. In der Literatur wird über eine Gesamtfläche des Septums von etwa 25 cm2 bis 33 cm2 berichtet, je nach Ge-schlecht und Ethnie der Patienten. Das Knorpelseptum (Länge ca. 3 cm, Dicke 0,7 bis 3 mm) zeigt oft eine nach posterior gerich-tete längliche Fortsetzung zwischen Vomer und Ethmoid. Der Vomer bildet den unteren und hinteren Anteil der Nasenschei-denwand und zieht bis zum Os sphenoidale hoch.

Die Nasenhöhlen werden durch drei paarige Nasenmuscheln in vier Etagen unterteilt, sodass die einströmende Luft über eine grosse Fläche erwärmt und befeuchtet wird. Eine mecha-nische Reinigung der Atemluft erfolgt zudem durch die Vibris-sae im Nasenvestibulum. Die grösste Nasenmuschel ist die Concha inferior, die als eigenständiger Knochen gilt. Diese Muschel erstreckt sich über die ganze Länge der Nasenhöhle (ca. 6 cm). Die mittlere und die obere Nasenmuschel gehören zum Ethmoid (Siebbein) und sind kürzer und kleiner als die untere Nasenmuschel. Alle Nasenmuscheln können radiolo-gisch eine Pneumatisierung zeigen, am häufigsten die mittlere Muschel (Concha bullosa).

Die vier Nasengänge (Meati nasales inferior, media et superior sowie Recessus sphenoethmoidalis) pro Seite haben diverse Öff-nungen, in die sich anatomische Nachbarstrukturen entleeren: im unteren Gang der Tränenkanal (Ductus nasolacrimalis), im mittleren Gang die Kieferhöhle, die vorderen Siebbeinzellen sowie die Stirnhöhle und im oberen Gang die hinteren Sieb-beinzellen. In die oberste Etage (Recessus sphenoethmoidalis)mündet die Keilbeinhöhle (Sinus sphenoidalis). Der mittlere Nasen gang wird auch als ostiomeataler Komplex bezeichnet wegen seiner komplizierten Verbindungen zu den diversen Nasen nebenhöhlen.

Der Nasenboden besteht aus den gleichen Strukturen, die auch den harten Gaumen bilden: aus palatinalen Fortsätzen des Os maxillae sowie aus horizontalen Fortsätzen des Os palatinum.Das Dach der Nase bilden die paarigen Nasenknochen sowie die Lamina cribriformis des Ethmoid. Die seitlichen Nasenwände sind kompliziert aus mehreren Knochen zusammengesetzt: Os maxillae, Os frontale, Os lacrimale, Os palatinum sowie Os eth-moidale. Grös sere Öffnungen in der lateralen Nasenwand sind der Hiatus semilunaris, u. a. mit dem Ostium maxillare, sowie das Foramen sphenopalatinum als Verbindung von der Nasenhöhle zur Fossa pterygopalatina.

Das Ethmoid (Os ethmoidale, Siebbein) ist ein sehr komplex gebauter Knochen und umfasst hauptsächlich die Siebbeinzel-len (Labyrinthe). Diese liegen medial zu den Augenhöhlen und drainieren zum mittleren und oberen Nasengang. Als anatomi-sche Varianten gelten die Agger-nasi-Zelle (vorderste Siebbein-zelle), die Haller-Zelle (liegt infraorbital oberhalb des Ostium maxillare), sowie die Onodi-Zelle (hinterste Siebbeinzelle mit enger Beziehung zum Canalis opticus).

RésuméLe Cone Beam ou « image volumétrique par faisceau conique » est un outil de diagnostic de plus en plus commun dans la méde-cine dentaire moderne. Selon la taille choisie de la prise de vue, on visualisera des structures dépassant le complexe dento-al-véolaire – structures dont l’anatomie doit être connue pour un

804-815_T1-1_vonarx_EDF.indd 813 01.10.19 11:09



diagnostic adéquat. Ce travail – premier d’une série de quatre – présente l’anatomie de la zone nasoethmoïdale ainsi que les pu-blications actuelles en rapport avec ce sujet.

Le nez se compose des structures externes, visibles – le dos et les ailes du nez – ainsi que des structures internes – les cavi-tés nasales. Le squelette du nez est composé d’une partie supé-rieure osseuse (Os nasale et Processus frontalis des Os maxillae)et d’une partie inférieure cartilagineuse (Cartilagines lateraleset Cartilagines alares). Le vestibule du nez relie les ouvertures externes – les narines – aux deux cavités nasales proprement dites (Cavum nasi). Ces dernières sont situées de part et d’autre d’une cloison sagittale médiane, le septum nasal. Cette cloison ostéo-cartilagineuse se compose de cinq parties distinctes : la lame perpendiculaire de l’ethmoïde, le vomer, le cartilage sep-tal ainsi que la Cresta nasalis des maxillaires et du palatin. La lit-térature parle d’une surface totale de 25 à 33 cm2 selon le sexe et l’appartenance ethnique du patient. Le cartilage septal (3 cm de long, 0,7 à 3 mm d’épaisseur) présente souvent un prolonge-ment postérieur entre le vomer et l’ethmoïde. Le vomer cons-titue la partie inférieure et postérieure de la cloison nasale se prolongeant vers le haut jusqu’au sphénoïde.

Les cavités nasales sont subdivisées en quatre étages par trois paires de cornets nasaux augmentant ainsi la surface d’échange permettant de réchauffer et d’humidifier l’air inspiré. Ce dernier sera de plus filtré mécaniquement par les vibrisses dans le vesti-bule du nez. Le cornet le plus grand – le cornet inférieur - est un os à part entière s’étendant sur toute la longueur des cavités na-sales (environ 6 cm). Les cornets moyens et supérieurs font par-tie de l’ethmoïde. Ils sont plus courts et plus petits que le cornet inférieur. Tous les cornets peuvent présenter une pneumatisa-tion, surtout le cornet moyen (Concha bullosa).

Les cavités nasales subdivisées en quatre étages par les cor-nets communiquent avec d’autres structures anatomiques par différents canaux. Le conduit lacrymonasal débouche dans le méat inférieur. Le sinus maxillaire, les parties antérieures et moyennes du labyrinthe ethmoïdal ainsi que le sinus frontal s’ouvrent vers le méat moyen ; la partie postérieure du laby-rinthe ethmoïdal vers le méat supérieur. Les sinus sphénoï-daux quant à eux communiquent avec l’étage supérieur des cavités nasales, les Recessus sphenoethmoidales. Au vu des nombreuses relations avec les différents sinus, on utilisera aussi le terme de complexe ostiomeatal pour évoquer le méat moyen.

La paroi inférieure des cavités nasales est composée des mêmes éléments que le palais dur : le processus palatin du maxillaire ainsi que la lame horizontale du palatin. La paroi supérieure est composée par les deux Os nasale ainsi que par la lame criblée de l’ethmoïde. La paroi latérale quant à elle est complexe dans sa constitution : le maxillaire, le frontal, le lacrymal, le palatin et l’ethmoïde en font partie. Ses ouver-tures les plus importantes sont le Hiatus semilunaris comprenant entre autres l’Ostium maxillare ainsi que le Foramen sphenopala-tinum (ouverture vers la fosse pterygopalatine).

L’ethmoïde est une structure osseuse particulièrement com-plexe dont la composante principale est le labyrinthe ethmoï-dal. Situé en médial de l’orbite, ce dernier se déverse dans la cavité nasale à hauteur des méats moyen et supérieur. On évo-quera les variantes anatomiques suivantes : la cellule d’Agger nasi (pneumatisation excessive d’une cellule ethmoïdale anté-rieure), la cellule de Haller (position infraorbitaire en dessus de l’Ostium maxillare) ainsi que la cellule d’Onodi (cellule la plus postérieure au contact du canal optique).

References

Ali M J, Nayak J V, Vaezeafshar R, Li G, Psaltis A J:Anatomic relationship of nasolacrimal duct and major lateral wall landmarks: Cadaveric study with surgical implications. Int Forum Allergy Rhinol 4: 684–688 (2014)

Bolger W E, Woodruff W, Parsons D S: CT demon-stration of pneumatization of the uncinate pro-cess. Am J Neuroradiol 11: 552 (1990)

Bornstein M M, Scarfe W C, Vaughn V M, Jacobs R:Cone beam computed tomography in implant dentistry: A systematic review focusing on guidelines, indications, and radiation dose risks. Int J Oral Maxillofac Implants 29 (Supple-ment): 55–77 (2014)

Bornstein M M, Tschopp M, Imesch M, Goldblum D:Die Dakryozystographie (DZG) zur Diagnostik bei Epiphora (article in German). Swiss Dent J 127: 24–25 (2017a)

Bornstein M M, Horner K, Jacobs R: Use of cone beam computed tomography in implant den-tistry: Current concepts, indications and lim-itations for clinical practice and research. Peri-odontol 2000 73: 51–72 (2017b)

Bremke M, Leppek R, Werner J A: Digital volume tomography in ENT medicine (article in Ger-man). HNO 58: 823–832 (2010)

Carter L, Farman A G, Geist J, Scarfe W C, Ange-lopoulos C, Nair M K, Hildebolt C F, Tyndall D, Shrout M: American Academy of Oral and Max-illofacial Radiology executive opinion state-ment on performing and interpreting diagnos-tic cone beam computed tomography. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 106: 561–562 (2008)

Caversaccio M, Boschung U, Mudry A: Historical review of Haller’s cell. Ann Anat 193: 185–190 (2011)

Cheng S Y, Yang C J, Lee C H, Liu S C, Kuo C Y, Lee J C, Shih C P: The association of superior attachment of uncinate process with pneu-matization of middle turbinate: A computed tomographic analysis. Eur Arch Otorhinolaryn-gol 274: 1905–1910 (2017)

Chmielik L P, Chmielik A: The prevalence of the Onodi cell – most suitable method of CT evalu-ation in its detection. Int J Pediatr Otorhinolar-yngol 97: 202–205 (2017)

Dahlstrom K, Olinger A: Anatomic description of the middle meatus and classification of the hia-tus semilunaris into five types based upon mor-phological characteristics. Clin Anat 27: 176–181 (2014)

Daultrey C, Hardman J, Anari S: The Caucasian nasal septum: An in vivo computed tomogra-phy study. Aesthet Surg 38: 717–722 (2018)

de Vos W, Casselman J, Swennen G R: Cone-beam computerized tomography (CBCT) imaging of the oral and maxillofacial region: A systematic review of the literature. Int J Oral Maxillofac Surg 38: 609–625 (2009)

Donmez B O, Agirdir B V, Sindel M M: Important anatomical landmarks in the lateral nasal wall. Saudi Med J 26: 1403–1408 (2005)

Doorly D J, Taylor D J, Schroter R C: Mechanics of airflow in the human nasal airways. Respir Physiol Neurobiol 163: 100–110 (2008)

Drake R L, Vogl A W, Mitchell A W M: Gray’s Anato-my for Students. Churchill Livingston, Elsevier, Philadelphia, PA, USA. 3rd edition: page 1075 (2015)

Dula K, Bornstein M M, Buser D, Dagassan-Berndt D, Ettlin D A, Filippi A, Gabioud F, Katsa-ros C, Krastl G, Lambrecht J T, Lauber R, Lueb-bers H T, Pazera P, Türp J C: SADMFR guidelines for the use of cone beam computed tomogra-phy/digital volume tomography. Swiss Dent J 124: 1170–1183 (2014)

Dula K, Benic G I, Bornstein M M, Dagassan-Berndt D, Filippi A, Hicklin S, Kissling-Jeger F, Luebbers H T, Sculean A, Sequeira-Byron P, Wal-ter C, Zehnder M: SADMFR guidelines for the use of cone beam computed tomography/digi-tal volume tomography. Swiss Dent J 125: 945–953 (2015)

El-Shaarawy E A A, Hassan S S: The sphenopala-tine foramen in man: Anatomical, radiological and endoscopic study. Folia Morphol (Warsz) 77: 345–355 (2018)

Elwany S, Salam S A, Soliman A, Medanni A, Talaat E:The septal body revisited. J Laryngol Otol 123: 303–308 (2009)

Eördögh M, Grimm A, Gawish I, Patonay L, Reisch R, Briner H R, Baksa G: Anatomy of the sphenopal-atine artery and its implications for transnasal neurosurgery. Rhinology 56: 82–88 (2018)

Gibelli D, Cellina M, Gibelli S, Cappella A, Oliva A G, Termine G, Sforza C: Anatomical variants of eth-moid bone on multidetector CT. Surg Radiol Anat 40: 1301–1311 (2018)

804-815_T1-1_vonarx_EDF.indd 814 01.10.19 11:09



Hafezi F, Naghibzadeh B, Nouhi A H: Applied anat-omy of the nasal lower lateral cartilage: A new finding. Aesthetic Plast Surg 34: 244–248 (2010)

Hafkamp H C, Bruintjes T D, Huizing E H: Function-al anatomy of the premaxillary area. Rhinology 37: 21–24 (1999)

Horner K, Islam M, Flygare L, Tsiklakis K, Whaites E:Basic principles for use of dental cone beam computed tomography: Consensus guidelines of the European Academy of Dental and Maxil-lofacial Radiology. Dentomaxillofac Radiol 38: 187–195 (2009)

Hur M S, Won H S, Kwak D S, Chung I H, Kim I B:Morphological patterns and variations of the nasal septum components and their clinical implications. J Craniofac Surg 27: 2164–2167 (2016)

Hwang K, Huan F, Kim D J: Mapping thickness of nasal septal cartilage. J Craniofac Surg 21: 243–244 (2010)

Hwang S H, Joo Y H, Seo J H, Kim S W, Cho J H, Kang J M: Three-dimensional computed tomog-raphy analysis to help define an endoscopic en-donasal approach of the pterygopalatine fossa. Am J Rhinol Allergy 25: 346–350 (2011)

Ila K, Yilmaz N, Öner S, Basaran E, Öner Z: Evalua-tion of superior concha bullosa by computed tomography. Surg Radiol Anat 40: 841–846 (2018)

Jacobs R, Salmon B, Codari M, Hassan B, Born-stein M M: Cone beam computed tomography in implant dentistry: Recommendations for clinical use. BMC Oral Health 18: 88 (2018)

Khojastepour L, Mirhadi S, Mesbahi S A: Anatomi-cal variations of ostiomeatal complex in CBCT of patients seeking rhinoplasty. J Dent (Shiraz) 16: 42–48 (2015)

Kim J, Han S H, Kim S W, Cho J H, Park Y J, Kim S W:Clinical significance of the sphenoidal process of the cartilaginous nasal septum: A prelimi-nary morphological evaluation. Clin Anat 23: 265–269 (2010a)

Kim J, Cho J H, Kim S W, Kim B G, Lee D C, Kim S W:Anatomical variation of the nasal septum: Cor-relation among septal components. Clin Anat 23: 945–949 (2010b)

Kim J, Kim S W, Kim S W, Cho J H, Park Y J: Role of the sphenoidal process of the septal cartilage in the development of septal deviation. Otolar-yngol Head Neck Surg 146: 151–155 (2012)

Koo S K, Kim J D, Moon J S, Jung S H, Lee S H: The incidence of concha bullosa, unusual anatomic variation and its relationship to nasal septal de-viation: A retrospective radiologic study. Auris Nasus Larynx 44: 561–570 (2017)

Lata S, Mohanty S K, Vinay S, Das A C, Das S, Choudhury P: Is cone beam computed tomog-raphy (CBCT) a potential imaging tool in ENT practice? A cross-sectional survey among ENT surgeons in the state of Odisha, India. Indian J Otolaryngol Head Neck Surg 70: 130–136 (2018)

Liu J, Dai J, Wen X, Wang Y, Zhang Y, Wang N: Imag-ing and anatomical features of ethmomaxillary sinus and its differentiation from surrounding air cells. Surg Radiol Anat 40: 207–215 (2018)

Mladina R, Antunovic R, Cingi C, Bayar Muluk N, Skitarelic N: Sinus septi nasi: Anatomical study. Clin Anat 30: 312–317 (2017)

Morton A L, Khan A: Internal maxillary artery variability in the pterygopalatine fossa. Otolar-yngol Head Neck Surg 104: 204–209 (1991)

Ogle O E, Weinstock R J, Friedman E: Surgical anatomy of the nasal cavity and paranasal sinuses. Oral Maxillofacial Surg Clin N Am 24: 155–166 (2012)

Pauwels R, Jacobs R, Singer S R, Mupparapu M:CBCT-based bone quality assessment: are Hounsfield units applicable? Dentomaxillofac Radiol 44: 20140238 (2015)

Perez-Pinas I, Sabate J, Carmona A, Catalina-Her-rera C J, Jimenez-Castellanos J: Anatomical variations in the human paranasal sinus region studied by CT. J Anat 197: 221–227 (2000)

Prades J M, Asanau A, Timoshenko A P, Faye M B, Martin C: Surgical anatomy of the sphenopala-tine foramen and its arterial content. Surg Ra-diol Anat 30: 583–587 (2008)

Sava C J, Rusu M C, Sandulescu M, Dinca D: Verti-cal and sagittal combinations of concha bullosa media and paradoxical middle turbinate. Surg Radiol Anat 40: 847–853 (2018)

Shpilberg K A, Daniel S C, Doshi A H, Lawson W, Som P M: CT of anatomic variants of the parana-sal sinuses and nasal cavity: Poor correlation with radiologically significant rhinosinusitis but importance in surgical planning. Am J Roentgenol 204: 1255–1260 (2015)

Stallman J S, Lobo J N, Som P M: The incidence of concha bullosa and its relationship to nasal septal deviation and paranasal sinus disease. Am J Neuroradiol 25: 1613–1618 (2004)

Stammberger H R, Kennedy D W: Paranasal Sinuses: Anatomic terminology and nomenclature. Ann Otol Rhinol Laryngol Suppl 167: 7–16 (1995)

Tatlisumak E, Aslan A, Cömert A, Ozlugedik S, Acar H I, Tekdemir I: Surgical anatomy of the nasolacrimal duct on the lateral nasal wall as revealed by serial dissections. Anat Sci Int 85: 8–12 (2010)

Trotier D: Vomeronasal organ and human phero-mones. Eur Ann Otorhinolaryngol Head Neck Dis 128: 184–190 (2011)

Tschopp M, Bornstein M M, Sendi P, Jacobs R, Goldblum D: Dacryocystography using cone beam CT in patients with lacrimal drainage system obstruction. Ophthalmic Plast Reconstr Surg 30: 486–491 (2014)

von Arx T, Lozanoff S: Clinical Oral Anatomy – A Comprehensive Review for Dental Practi-tioners and Researchers. 1st edition, Springer International, Switzerland (2017)

von Arx T, Nakashima M, Lozanoff S: The face – A musculoskeletal perspective: A literature review. Swiss Dent J 128: 678–688 (2018a)

von Arx T, Schaffner M, Bornstein M M: Patent nasopalatine ducts: An update of the literature and a series of new cases. Surg Radiol Anat 40: 165–177 (2018b)

Wilhelm K E, Rudorf H, Greschus S, Garbe S, Lüssem M, Lischka T, Schild H H, Gerstner A O:Cone-beam computed tomography (CBCT) da-cryocystography for imaging of the nasolacri-mal duct system. Klin Neuroradiol 19: 283–291 (2009)

Wormald P J: The agger nasi cell: The key to un-derstanding the anatomy of the frontal recess. Otolaryngol Head Neck Surg 129: 497–507 (2003)

Zhang L, Han D, Ge W, Tao J, Wang X, Li Y, Zhou B:Computed tomographic and endoscopic analy-sis of supraorbital ethmoid cells. Otolaryngol Head Neck Surg 137: 562–568 (2007)

804-815_T1-1_vonarx_EDF.indd 815 01.10.19 11:09

thomas von arx1 2 extraoral anatomy in cbct - michael m ... · fourth concha suprema (santorini’s...

Documents