Anatomy

Gray’s Anatomy describes the platysma as a broad sheet arising from the fascia of the upper pectoralis major and deltoid. Having crossed the clavicle, fibers ascend superomedially to insert into the mandible, skin, and subcutaneous tissues of the lower face, often blending with the lower oral and angular muscles. The importance of platysmal manipulation in aesthetic neck surgery was first noted in the 1920s.

Three common decussation patterns have been described ( Figs. 14.1 and 14.2 ). The importance of understanding this lies in the fact that mentohyoid decussation provides a continuous sheet for submental support. The 10% of individuals in whom there is no decussation—that is, separation—therefore have minimal structural support. Bands may be medial and lateral; Rohrich et al. have observed that it is only necks with no decussation that can produce medial vertical bands. This is not the entire story, however, because platysma bands may form not only at the leading edge; many static bands result from anterior folding against the relatively fixed midline. Consider the linea alba in the abdomen—a corollary is the jowl that forms only because the mandibular ligament prevents further anterior translocation of the descending cheek substance. Bands may be narrow (<2 cm) or wide (>2 cm) in their separation, and the latter are frequently associated with more fat excess. The prime function of the platysma facial expression, where it conveys fright, sadness, or horror.

De Castro’s anatomic platysma variation patterns. (A) Type I. (B) Type II. (C) Type III.

(Adapted from de Castro, C.C., 1984. The value of anatomical study of the platysma muscle in cervical lifting. Aesth. Plast. Surg. 8, 7–11.)

The cause is controversial, with two differing views. First, many believe them to be essentially hypertrophic muscle bands. In fact, most adults have some degree of dynamic banding (i.e., on forced contraction; see Fig. 14.1C ). Bands apparent at rest are referred to as static.

Others believe them to be age-related, due to a combination of superficial musculoaponeurotic system (SMAS) attenuation, ptosis, and redundancy, which stops conformation of the tissues to the cervical concavity, and to the stretching of skin and fat overlying the muscles—the two sides of the triangle becoming the hypotenuse. Traditional management was based on tightening of the skin and SMAS, with a repositioning of the platysma muscle to its more usual posterior location. However, a more recent concept is skin redraping after structural reconstitution of the cervicomental angle by midline apposition. Many years of experience have demonstrated that lateral traction alone, however simple in its attraction, is insufficient. Gonzalez has proposed a different view, noting that the sagging senescent skin and platysma become fibrosed, therefore fixing the bands in a static state. However, 30 years of neck lifting have not convinced me, and the bands are not seen when a person is lying supine. Being a skin muscle—part of the panniculus carnosus—the platysma has the same embryonic origin as adjacent skin, so loss of tone is twofold; that is, seen in both skin and muscle.

Iatrogenic (e.g., postliposuction) risk factors were found to be submental obesity and, perhaps unsurprisingly, platysmal nondecussation. Suction of the fat undoubtedly exposes platysmal pathology previously hidden from view.

Management Options