Surgical Anatomy of the Superficial Musculo-Aponeurotic System (SMAS)

Key points

  • The face lift is one of the procedures in facial cosmetic surgery that is performed to help rejuvenate the aging face.

  • The face lift, also known as rhytidectomy, addresses the aging face by various methods, removing redundant or lax facial skin and repositioning and modifying subcutaneous, facial, and muscular elements of the face and neck.

  • The face lift procedure may also combine other facial cosmetic procedures, such as skin resurfacing and skeletal augmentation, to maximize the aesthetic outcome.

  • Mitz and Peyronie’s landmark article in 1976 provided understanding of the superficial musculo-aponeurotic system (SMAS) in the parotid and cheek area, which led to face lifts with more desirable aesthetic and longer-lasting outcomes.

  • Over the past 3 decades, developments have been made in techniques involving composite, deep plane, subperiosteal, laser, and endoscopic face lifts.

  • The key principals in the face lift are shared by all techniques; proper patient selection, preoperative planning, and expert knowledge of surface anatomy are critical to an excellent surgical outcome.

The face lift is one of the procedures in facial cosmetic surgery that is performed to help rejuvenate the aging face. The face lift, also known as rhytidectomy, addresses the aging face by various methods: removing redundant or lax facial skin and repositioning and modifying subcutaneous, facial and muscular elements of the face and neck. The face lift procedure may also combine other facial cosmetic procedures, such as skin resurfacing and skeletal augmentation. to maximize the aesthetic outcome.

Mitz and Peyronie’s landmark article in 1976 provided understanding of the superficial musculo-aponeurotic system (SMAS) in the parotid and cheek areas; this deeper understanding of the SMAS has led to face lifts with more desirable aesthetic and longer-lasting outcomes.

Over the past 3 decades, developments have been made in techniques involving composite, deep plane, subperiosteal, laser, and endoscopic face lifts. The choice of procedure is generally surgeon dependent. The key principals in the face lift are shared by all techniques; proper patient selection, preoperative planning, and expert knowledge of surface anatomy are critical to an excellent surgical outcome.

When rhytidectomies were performed in the early 1900s, surgeons in Europe and the United States were experimenting with removal of skin strips from in front and behind the ears. In the 1920s, surgeons were performing more extensive cervicofacial skin undermining. In 1974, Skoof first described an interconnected skin-fat-musculofascial unit; this was his concept of a deep plane face lift. The extent of the deep plane dissection would not be considered deep plane by modern surgeons, but was the foundation for future techniques.

Anatomy of the aging face

During the initial examination, the surgeon must determine the extent of photo aging, and determine whether the aging process is due to photo aging or a result of loss and atrophy of subcutaneous fat, redistribution of fat, or atrophy of muscle of facial expression. Each face ages in a relatively similar sequence of events; the variation exists between the start and duration of each event. Some races show signs of aging in the late 20s, and other racial groups do not show clinically evident changes until the late 30s or early 40s. Overall, there is a general sagging from the forehead to the chin, clinically appearing as lines and folds. One can also see resorption and redistribution of fat; specifically this can be observed in the temporal and cheek area. The eyes can appear more withdrawn as the boney orbit looses volume from bone resorption and fat loss. The nose appears longer as the upper and lower cartilages separate. Alveolar bone loss in combination with loss of dentition can give the appearance of excessive soft tissue in the perioral region. As the chin descends downward, it further lengthens the face. The neck ages due to the laxity in the platysma muscle and descent of the hyoid bone and larynx. This can be seen as anterior banding of the platysma. Increased fat in the submental area also attributes to a sagging appearance, which is diagrammed in Figs. 1 and 2 .

Fig. 1
Cervical changes with aging. ( A ) A youthful neck with sharp cervicomental angle and a strong mandibular line. ( B ) Early loss of the cervicomental angle and mandibular line. ( C ) Chin ptosis, accumulation of submental and submandibular fat, laxity of submental skin. ( D ) An accentuation of the previous changes, plus banding of the anterior platysma. ( E ) Further descent and retrusion of chin (anterior mandibular recession). ( F ) Descent of the hyoid accentuates the other changes.
( From Larrabee WF Jr, Makielski KH. Surgical anatomy of the face. New York: Raven Press; 1992. p. 18; with permission.)

Fig. 2
Hypertrophic digastric muscles ( A and B ) and a low hyoid position ( C and D ) are the 2 most difficult anatomic variants to improve during face lifting. These variants often go unnoticed until after a face lift ( E ). It is critical to inform patients of the limitations of treatment.
( From Bagheri SC, Bell RB, Khan HA. Current therapy in oral maxillofacial surgery. St Louis (MO): Elsevier Saunders; 2012. p. 952; with permission.)

Anatomy of the aging face

During the initial examination, the surgeon must determine the extent of photo aging, and determine whether the aging process is due to photo aging or a result of loss and atrophy of subcutaneous fat, redistribution of fat, or atrophy of muscle of facial expression. Each face ages in a relatively similar sequence of events; the variation exists between the start and duration of each event. Some races show signs of aging in the late 20s, and other racial groups do not show clinically evident changes until the late 30s or early 40s. Overall, there is a general sagging from the forehead to the chin, clinically appearing as lines and folds. One can also see resorption and redistribution of fat; specifically this can be observed in the temporal and cheek area. The eyes can appear more withdrawn as the boney orbit looses volume from bone resorption and fat loss. The nose appears longer as the upper and lower cartilages separate. Alveolar bone loss in combination with loss of dentition can give the appearance of excessive soft tissue in the perioral region. As the chin descends downward, it further lengthens the face. The neck ages due to the laxity in the platysma muscle and descent of the hyoid bone and larynx. This can be seen as anterior banding of the platysma. Increased fat in the submental area also attributes to a sagging appearance, which is diagrammed in Figs. 1 and 2 .

Jan 23, 2017 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Surgical Anatomy of the Superficial Musculo-Aponeurotic System (SMAS)
Premium Wordpress Themes by UFO Themes