Pearls

An essential initial step in the arduous ascending pathway to the successful rhinoplasty is a clear understanding of the nasal anatomy and its function. It has been repeatedly stated that form and function are inalienable components of most facial structures and the nose is no exception. It is of cardinal importance to recognize that the nose has several important functions and maintaining sound structural support during the rhinoplasty is crucial to its shape and physiology. This is where the understanding of the nasal anatomy becomes an irreplaceable component of a positive rhinoplasty outcome. In this chapter, we will first discuss the anatomy of the nose, followed by its function as it relates to the rhinoplasty. We will begin with the surface of the nose and extend the discussion to the deeper structures.

Rhinoplasty Terminology

Even though the nose occupies only a small area of the face, the terminology used to define the different parts of the nose is vast and confusing. In order to improve understanding of this terminology, we will try to list and explain these terms, as described in different textbooks,^1,2,26 including all variations that have been used to describe a specific site (Figures 1.1–1.4).

Figure 1.1 Front view of the different anatomical components of the nose.

Figure 1.2 Front view of the bony and cartilaginous nasal frame.

Figure 1.3 Profile view of the different anatomical components of the nose.

Figure 1.4 Profile view of the bony and cartilaginous nasal frame.

Figure 1.5 The average skin thickness is greatest (1.25 mm) at the radix and least at the rhinion.

Soft Tissues of the Nose

The tissues covering the nasal frame vary significantly in thickness from the cephalic to the caudal portion. These tissues are thick cephalically and caudally, and become thinner in the center. It is for this reason that a nose frame that is totally straight on profile most likely will not induce an optimal dorsal outline. The soft tissue components of the nose include skin, muscles, nerves, and the vascular elements. In general, the nose has more sebaceous glands than most other parts of the face and body. Therefore the skin of the nose will re-epithelialize faster than other types of skin following procedures such as dermabrasion, chemical peel, and laser abrasion. The sebaceous glands are more abundant in the caudal third of the nose skin than the middle and cephalic portions. The thickness of the cephalic portion of the nose skin is related more to components such as the procerus muscle and adipose tissue than to a thick dermis and sebaceous glands.

Skin

One of the key determining factors in the outcome of the rhinoplasty is the quality of the nasal skin. The skin color, consistency, thickness, and porous nature vary from patient to patient, on different parts of the same patient’s nose and at different stages of life. The skin is thicker at the radix than the central portion. However, in some patients the supratip area is even thicker than the radix and contains more sebaceous glands. Lessard & Daniel have determined that the average skin thickness is greatest at the radix (measuring 1.25 mm) and the least at the rhinion (approaching 0.6 mm) (Figure 1.5).¹

The lower third of the nose, especially the supratip area, has an abundance of sebaceous glands which range in activity from time to time and race to race. In men, especially teenagers, there is a vast number of these glands within the tip and supratip area that renders achievement of an optimal tip definition difficult. A varying degree of rosacea may alter the skin surface color, causing some redness in the mid-vault area, or more commonly, in the caudal half of the nose, especially the supratip area. This redness commonly extends to the cheek area. The thickness of the skin is reduced dramatically in the columella and mid-alar area, while it thickens in the alar base area. As much as thick skin is problematic in achieving an ideal nasal definition, thin skin may also adversely affect the outcome of rhinoplasty by revealing harshness of the underlying frame and any existing iatrogenic or residual minor flaws, which would not be discernible in a patient with thicker skin.

The alar base area contains more fibrous bands, which is the reason for its rigidity. The vestibule is the cavity just inside the external nares bounded by the membranous septum and the columella medially and the side wall of the ala laterally, the latter being covered with hair (vibrissae).²

Soft Tissue Layers Beneath the Skin

There are four distinct layers that occupy the area between the skin and the underlying osseocartilaginous frame: the superficial musculoaponeurotic system (SMAS) as originally described by Tessier,³ fibromuscular layer, deep fatty layer, and periosteum/perichondrium.² Immediately under the skin, there is a superficial fatty panniculus, which is largely occupied by adipose tissue containing some vertical fibers and septi running from the skin to the underlying SMAS.² This layer again is significantly thicker in the radix area, and becomes extremely thin in the mid-vault region and thickens in the supratip area. The SMAS of the nose is the continuation of the sheath that extends across the entire upper half of the face.

Under the SMAS there is a thin fibrofatty layer that divides to encase the superficial and deep muscles of the nose.^3,4 Wherever there is no muscle, these two layers join, creating a single layer.

The third layer of the nose is the deep fatty layer that separates the fibromuscular layer from the underlying nasal frame. The major superficial blood vessels and motor nerves run within it. A distinct feature of this layer is that it does not have fibrous septa and its role is to facilitate movement of the fibromuscular layer over the frame.

The fourth soft tissue layer is the periosteum over the nasal bones and the perichondrium over the cartilaginous frame. There are several fibrous connections joining the cartilages to each other, some extending from the lateral crura of the lower lateral cartilages to the upper lateral cartilages and connecting the accessory cartilages to each other. There is a fibrous band extending from one lateral crus to the opposite one in the supratip area which is called the Pitanguy ligament.⁵ Additionally, there are dense fibrous bands between the caudal septum and the medial crura. There are also fibrous bands between the medial crura.

Nasal Muscles

The importance of the musculature of the nose has not been sufficiently emphasized in the literature. Because these muscles are thin and difficult to visualize, it is a challenge to consistently preserve them. The significance of these small nasal muscles is clearly evident in patients who suffer from facial paralysis. In the early stages after facial paralysis, even without a significant nasal deviation, these patients experience a notable blockage of the nasal airway on the ipsilateral side to the paralysis. After the nose shifts to the opposite side of the paralytic face, the deviation becomes conspicuous and the airway becomes more reduced. Additionally, in patients in whom the nasal muscles are iatrogenically disturbed during rhinoplasty, the result is a disconcerting functional and aesthetic change, an adverse event that is especially evident on animation. This type of muscle dysfunction is a hallmark of rhinoplasties performed several decades ago when the dissection was conducted in a supraperiosteal plane, irreparably damaging the thin nasal muscles.

The description of the muscles of the nose and explanation of their functions is one of the most confusing aspects of the body of knowledge germane to rhinoplasty. In fact, many of the articles written about the nasal musculature assign different names and functions to the same muscles of the nose. All these muscles are innervated by the VIIth cranial nerve. The following is a description of the nasal muscles and an outline of their function⁶ (Figures 1.6 and 1.7).

Figure 1.6 Profile view illustration depicting the nasal musculature.

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Rhinogenic Migraine Headaches Elongation of the Short Nose Correction of the Overprojected Nose Achieving Optimal Tip Projection Secondary Rhinoplasty Patient Assessment for Rhinoplasty

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