Point One: Mental Prominence

The mentum should be evaluated for anterior, lateral, and inferior projection. This should reveal a sculpted, well-de-fined border on both anterior and profile views.2 A projected mentum combined with an acute CMA visually separates the face from the neck. Photographers and artists accentuate this separation by casting a shadow into the submental triangle and anterior neck ( Fig. 2.2 ).

A weak, receding chin creates the illusion of a short neck. In a series of chin augmentations, Courtiss demonstrated that augmenting a deficient mentum can improve the aesthetic balance of the neck.3 Anteroposterior mental deficiencies (horizontal microgenia) are easily augmented with alloplasts. Chin implants are significantly less effective in correcting vertical and transverse deformities. For more complex deformities of the chin, bony osteotomy of the chin (genioplasty) is indicated.

Evaluation of the chin should focus on its appearance in three-dimensional view. When viewed in profile, the ideal projection of the chin can be estimated by dropping a vertical line from the vermilion border of the lower lip ( Fig. 2.3 ).4 In the aesthetic neck, the pogonion reaches this vertical line. The mental soft tissue will fall short of this line with microgenia or retrognathia. The ideal projection of the chin is gender-specific. It is acceptable for the pogonion in men to extend slightly beyond the ideal vertical line and for the pogonion in women to be slightly positioned behind this line.

Point Two: Hyoid Position

The more superior and posterior the hyoid bone, the more acute and more attractive the CMA. An inferiorly, anteriorly positioned hyoid bone can create an obtuse cervicomental deformity in the absence of microgenia, accumulation of submental fat, or platysmal laxity. Malpositioned hyoid bones are commonly referred to as “problem necks.” Intra-operative repositioning of the hyoid bone is challenging and typically requires transecting the submental musculature. Without myotomy, the patient should be counseled about the anatomical limitations of surgery to reposition the hyoid bone.

Guyuron reviewed dozens of cephaloxerograms and related hyoid-bone position to attractive and unflattering CMAs.5 He concluded that in a balanced neck the caudal border of the hyoid bone is at or above the level of the menton (the most inferiorly projecting point of the chin). An anteriorly, inferiorly located hyoid bone will limit the ability to surgically create a well-contoured submental triangle.

Point Three: Cervicomental Angle

The CMA is created by connecting a horizontal line extending through the menton with an oblique line following the anterior border of the neck ( Fig. 2.4 ). The ideal CMA is between 105 and 120 degrees. When present in aesthetic proportions, this angle reveals a harmonious separation of the face and neck. The lower one-third of the face appears projected and the neck elongated.

Powell and Humphrey described this anatomical region in terms of a mentocervical angle (MCA) ( Fig. 2.5 ).6 The MCA is formed by the intersection of a vertical line drawn from the glabella (G) (the most prominent point of the forehead in a profile view) to the pogonion (P) (the anteriormost point of the chin) with a horizontal line connecting the menton (M) to the cervical point (C) (the innermost point between the submental area and the neck). The ideal MCA is between 80 and 95 degrees. An obtuse MCA blurs the distinction between the face and neck.

The CMA and MCA are two of many means used to evaluate the submental triangle. Dedo chose to avoid mathematical analysis and described the ideal submental triangle as flat.7 A submental convexity will create the illusion of a short neck. A submental concavity will skeletonize the musculature in the floor of mouth. Submental accumulation of fat, laxity of the platysma muscle, an anteriorly located hyoid bone, and microgenia are all conditions affecting the submental triangle. It is important that the surgeon specifically identify the condition (s) contributing to an unattractive neck. Only then will the surgeon be able to accurately treat the responsible deformity.

Point Four: Definition of the Mandibular Border

The top of the neck is formed by a well-defined mandibular body and a prominent chin. A mandible with ideal height, length, and projection will create an angular jaw–neck contour. The inferior border of the mandible is lined by a shadow from the bony mentum to the mandibular gonion. This line should be free of blunting from ptosis of the submandibular gland and uninterrupted by jowl overhang. To improve the definition of the mandibular border, liposuction can be used above and below the mandible; however, a strip of subcutaneous fat should be left along the mandibular border to highlight the border itself.8

The ideal bony mandibular angle is well-defined and projected both laterally and inferiorly. Gonial deficiency can be corrected with a bone implant that wraps around the posterior and inferior borders of the mandibular angle. A sculpted posterior border of the angle distinguishes the face from the SCM muscle.