1 Anatomy of the Nose

Successful outcomes in rhinoplasty require a thorough knowledge of anatomy, as in every field of surgery. Any knowledge gaps relating to anatomical structures and relationships should be filled by training on suitable specimens in anatomical or forensic institutes, or in specialized training centers. After years of experience in various training institutions, I can particularly recommend the courses offered by the European College of Aesthetic Medicine and Surgery (ECAMS; https://www.ecamedicine.com/). In these courses, rhinoplasty is learned step by step, theoretically and practically, using excellent material in a relatively small group with a very good ratio of lecturers to learners; the training situation is very similar to an intraoperative setting ( ? Video 1.1).

Video 1.1 The European College of Aesthetic Medicine and Surgery (ECAMS) rhinoplasty course.

Surgical courses that offer practical exercises on specimens and observation of live operations, as well as imparting theoretical knowledge, are particularly valuable.

1.1 The Bony Framework

The external skeleton of the nose consists of the nasal bones and the frontal process of the maxilla on either side ( ? Fig. 1.1). The internasal suture runs between the nasal bones, separated from the frontal process of the maxilla by the nasomaxillary suture. The inferior borders of these bones form the piriform aperture.

Fig. 1.1 Bony nasal framework. The nasal bones form the bony framework of the outer nose together with the frontal processes of the maxilla.

The "K-area" is the transitional zone between the cartilaginous and bony framework of the nose - i.?e., at the rhinion - where the edges of these structures overlap.

The posterior aspect of the nasal septum comprises two bones, namely the perpendicular plate of the ethmoid and the vomer ( ? Fig. 1.2).

Fig. 1.2 Inner nose, sagittal; view of the septum. The cartilaginous quadrangular plate and the bony perpendicular plate, together with the vomer, are the supporting elements of the nasal septum.

The nasal septum sits on the maxillary crest of the palate, which merges into the premaxilla, with its anteriormost part being the anterior nasal spine. The posterior edge of the vomer forms part of the choanae, the posterior nasal apertures. The nasal cavities and paranasal sinuses (frontal, sphenoidal, and maxillary sinuses, and ethmoid air cells) are closely related and interconnected. Ostial patency and optimal aeration of the paranasal sinuses is paramount for ensuring healthy upper airways ( ? Fig. 1.3).

Fig. 1.3 Inner nose, deep cross-section at the level of the maxillary sinuses. The cross-section shows the close relationship of the nasal cavities to the paranasal sinuses.

The turbinates (superior, middle, and inferior nasal conchae) also have a bony framework. The inferior turbinate is the largest of these and the most important for regulating nasal airflow.

Pathological processes may involve both the nasal septum and the inferior and middle turbinates. Nasal septal deviation may frequently be present, while the inferior turbinate is susceptible to hypertrophy. Surgical diminution of the turbinates is thus often needed in order to relieve nasal obstruction ( ? Fig. 1.3, ? Fig. 1.4)

Fig. 1.4 Inner nose, cross-section. The septum and the inferior turbinates are most commonly involved in functional disorders of the nose.

Most of the inferior turbinate consists of vascularized soft tissue, covered with mucous membranes, and not of bone ( ? Fig. 1.5, ? Fig. 1.6). Persistent nasal congestion is therefore most commonly due to inferior turbinate hypertrophy and may require surgical diminution of the soft tissues overlying the turbinate.

Fig. 1.5 Inner nose, view of the lateral wall. The three turbinates divide the nasal cavity into three meatus. The ostium of the maxillary sinus opens into the middle meatus, while the lacrimal duct opens into the inferior meatus.

Fig. 1.6 Nasal turbinates and mucosa. (a) Frontal section through the nose. The nasal mucosa is unswollen on the left side and swollen on the right. 1, Middle turbinate; 2, maxillary sinus, ostium; 3, nasal septum; 4, inferior turbinate. (b) Respiratory mucosa. 5, Mucus layer; 6, respiratory epithelium with cilia; 7, goblet cells; 8, mucosal glands.

Fig. 1.7 Bony and cartilaginous framework of the nose. The nasal cartilage is partly covered by bone at its cranial aspect.

The inferior turbinates and the floor of the nasal cavity form the boundaries of the inferior meatus, while the middle meatus lies between the middle and lower turbinates. The maxillary sinus opens into the middle meatus, and the nasolacrimal duct into the inferior meatus (see ? Fig. 1.3, ? Fig. 1.5).

1.2 The Cartilaginous Framework

The anterior two-thirds of the nasal framework consists of cartilage, which provides the mobility and flexibility needed in view of the frequent movement of the nose and repeated touching of the nasal tip. The septum, to which the upper lateral cartilages (ULC) are fused, and the alar cartilages are the most important cartilaginous structures of the nose, both from a functional and a surgical point of view ( ? Fig. 1.7).

A variable portion of the cranial aspect of the cartilaginous septum and the upper lateral cartilages in the "K-area" is virtually buried beneath the nasal bones and is directly accessible only after removal of the overlying bone (e.?g., during correction of a nasal hump). This anatomical detail is of the utmost importance from the surgical viewpoint ( ? Fig. 1.1, ? Fig. 1.7).

A small triangular region of the lateral nasal wall between the upper lateral cartilage, the lateral crus of the alar cartilage (i.?e., the lower lateral cartilage, LLC), and the piriform aperture consists only of fibrous tissue, unsupported by stable structural elements (see ? Fig. 1.1).

The caudal end of the upper lateral cartilage articulates with the cranial (i.?e., cephalic) rim of the lateral crus of the alar cartilage as an "alar scroll," with the edge of the upper lateral cartilage curling outward and that of the lower lateral cartilage curling inward. This cartilaginous articulation may be either loose or rigid ( ? Fig. 1.8).

Fig. 1.8 Intercartilaginous fold with "scroll." The upper and lower lateral cartilages (ULC, LLC) are connected at the intercartilaginous fold by an undulating segment of cartilage (scroll).

This area is of particular functional importance for nasal breathing. Here, the lateral nasal wall and the septum form what is known as the (inner) nasal valve at the level of the caudal rim of the upper lateral cartilage.

The angle of opening of this valve plays a crucial role in regulating nasal airflow ( ? Fig. 1.9) and should be at least 15° to allow smooth nasal breathing.

Fig. 1.9 The nasal valve. (a) Normal opening angle of the nasal valve. (b) Narrow opening angle, with so-called tension nose.

A smaller angle may result in obstruction of nasal breathing despite a stable cartilaginous framework. This is typically seen in the "tension nose," characterized by a high, narrow nasal bridge with a high anterior septal angle (see case study, ? Fig. 10.13). If the cartilage is weak or compromised by prior rhinoplasty, it may result in collapse of the internal nasal valve despite a normal angle.

The importance of the counterpart, the external nasal valve, must also not be underestimated. This valve is represented by the nostril, bounded medially by the caudal septum and laterally by the caudal edge of the alar cartilage, which may also be floppy and weak. Preoperative evaluation should focus on precise localization of the vulnerable area if a functional disorder is present. Alar rim grafts can be used to reinforce weak external nasal valves (see section ? 10.3).

1.2.1 The Alar Cartilages

The alar cartilages constitute a...