35.1 Introduction

Traditional facelift surgery relies on the tightening of skin and subcutaneous tissue in order to restore a youthful appearance to the aging face. In 1976, Mitz and Peyronie [1] provided a detailed anatomic description of the superficial musculoaponeurotic system (SMAS) as a distinct layer deep to the subcutaneous tissue. Years before the SMAS was formally described, Skoog [2] used the SMAS for plication and flap suspension in his facelift procedures. In recent years, the use of the SMAS has been described in a multitude of facelift techniques. Some prefer plication or imbrication of the SMAS layer. Others advocate the sub-SMAS biplanar approach with deep or extended SMAS dissection.

Modifications to the limited SMAS dissection may achieve the goal of improved facial contouring with long-lasting effects. Nonetheless, the risk of facial nerve injury is greater with the inclusion of SMAS elevation anterior to the parotid gland as compared with a standard SMAS dissection. Given the proximity of the facial nerve to the plane of dissection, surface anatomic landmarks are necessary to predict the location of the nerve as it courses deep to the SMAS layer.

The safe facelift technique addresses these needs and provides the surgeon with bony anatomic

B.J. Wilhelmi ( )

Plastic Surgery Division, Department of Surgery, University of Louisville, 2nd floor ACB Building, 550 South Jackson Street, Louisville,

KY 50202, USA

e-mail: bjwilh01@louisville.edu

Y. Hazani

Aesthetic Surgery Fellow Harvard,

Massachusetts General Hospital,

Boston, MA, USA

landmarks to elevate the SMAS. While soft tissue landmarks can vary significantly among patients and even change position with aging, the use of facial bony prominences can serve as a more reliable method. Prior to utilizing the anatomic landmarks for elevating the SMAS, a thorough understanding of the pertinent anatomy is necessary.

35.2 Anatomic Considerations

The soft tissue of the face is arranged in multiple consistent layers with retaining ligaments that anchor the soft tissue to the facial skeleton. Structures within each layer maintain their anatomic location while the thickness of each layer can change as the dissection proceeds medially. The six distinct layers are, skin, subcutaneous fat, superficial facial fascia (SMAS), mimetic muscles, deep facial fascia (parotidomasseteric fascia), and the plane of the facial nerve, buccal fat pad, parotid duct, and the facial artery and vein.

35.2.1 The Facial Nerve

The facial nerve originates in the pons between the cranial nerves VI and VIII (Table 35.1) [3–8]. The facial nerve leaves the calvarium, passing through the facial canal of the temporal bone to exit from the stylomastoid foramen. The main trunk of the facial nerve courses 0.5–1.5 cm before entering the posterior aspect of the parotid gland. The critical landmarks which can be used to identify the main trunk of the facial nerve include 1 cm below the conchal cartilaginous pointer, and 6–8 mm below the tympanomastoid

sulcus, where it crosses the styloid process and the anterior to posterior belly of the digastric muscle.

The facial nerve enters the parotid gland and splits it into superficial and deep lobes. Within the parotid gland, the nerve divides into an upper and lower portion. Further divisions and intercommunications result in five major branches that emerge through the anterior border of the parotid gland. These are the frontal, zygomatic, buccal, marginal mandibular, and cervical branches.

The frontal branch courses cranially and over the zygomatic arch in a consistent course from 0.5 cm below the tragus to 1.5 cm above the lateral brow. Stuzin et al. defined the location of the frontal branch in three-dimensional planes on the underside of the temporoparietal fascia (superficial temporal fascia). In the temporal region, the frontal branch innervates the frontalis, lateral orbicularis oculi, corrugator supercilii, and procerus muscles.

The buccal, zygomatic, and marginal branches exit the anterior edge of the parotid gland and proceed along the superficial layer of the masseter, immediately below the deep facial fascia. The zygomatic branch extends toward the zygomaticus major muscle and provides motor innervation to the upper third of the muscle belly. Some fibers cross over the anterior

aspect of the zygomaticus major muscle and arborize within the orbicularis oculi muscle.

The buccal branch courses over the buccal fat pad and join the plane of the parotid duct, and the facial artery and vein. A rich plexiform of nerve connections between the buccal and zygomatic branches innervates the mimetic muscles of the buccal region. These include muscles responsible for movement of the cheeks, nostrils, nasolabial fold, upper lip, and oral commisures.

Along the inferior border of the mandible, the marginal mandibular branch crosses over the facial vessels and proceeds toward the major lip depressors and mentalis muscle. The cervical branch emerges from the caudal edge of the parotid gland and courses in a longitudinal vector. In the neck, it is deep to the platysma and the deep cervical fascia. The cervical branch innervates the platysma muscle (Table 35.1).

35.2.2 The SMAS Layer

The SMAS is a strictly superficial anatomical structure of the face derived from the primitive platysma, and does not possess any bony insertions. It is composed of