Enhanced study of facial soft tissues using a novel large scale histology technique

Self Cite

As Voltaire (1756) said, the Holy Roman Empire was neither holy nor Roman, nor an empire. Analogously, the superficial musculoaponeurotic system (SMAS) is neither aponeurotic nor an entire system.-K. Hwang (2018) The term superficial musculoaponeurotic system (SMAS) was originally described by Mitz and Peyronie in 1976 as a distinct musculoaponeurotic layer between the superficial fat and the deep fat responsible for complex facial mimicry. 1 From thereon, this term has been inextricably linked to face-lift surgery: where the layer of dissection is described in reference to the SMAS, being either superficial to or deep to the SMAS. This supposed layer is used to safely lift sagged facial tissues. In the layered anatomy of the face, the SMAS is categorized as layer 3, situated between the subcutaneous fat (layer 2) and the areolar plane of the spaces (layer 4). 2Background: The exact anatomical entity behind the term superficial musculoaponeurotic system (SMAS) remains poorly understood. The different interpretations of the term SMAS by anatomists, surgeons, and histologists have caused confusion. This article aims to provide clarity regarding this term and the relevant anatomy. Methods: A literature review was conducted to uncover the variety of descriptions of the term SMAS. A feasibility study, followed by a conclusive series of standardized layered dissections complemented by histologic analysis and sheet plastination, was performed on 50 cadaver heads (16 embalmed and 34 fresh; mean age, 75 years). Results: Most literature considers the SMAS as layer 3, that is, a musculoaponeurotic layer that separates the subcutaneous fat of the superficial fascia from the deep fat of the deep fascia. The authors' dissections, histologic analysis, and sheet plastination demonstrated that layer 3 is present only where there are flat mimetic muscles and platysma-auricular fascia over the posterior part of the parotid gland as the evolutionary remnant of the platysma, but not between the flat mimetic muscles. Here, the subcutaneous fat is in direct contact with the deep fat without the interposition of a musculoaponeurotic layer 3. Conclusions: Because of the absence of a distinct and complete layer 3 connecting the flat mimetic muscles, the authors conclude that the SMAS as originally described does not exist as a specific anatomical entity. In retrospect, the surgically created compound layered flap composed of a variable thickness of subcutaneous fat, mimetic muscles (eg, platysma, orbicularis oculi), and a thin layer of deep fascia is what is known as the "SMAS." (

Section: Methodsmentioning

confidence: 99%

The Superficial Musculo-Aponeurotic System (SMAS): Does it Really Exist as an Anatomic Entity?

Minelli

Lei

Mendelson³

2023

Self Cite

“…Histologic analysis of full-thickness macrosections of the face and neck was performed in 73 samples from 11 fresh cadavers (six male and five female cadavers; mean age, 81 years). 27 …”

Section: Methodsmentioning

confidence: 99%

“…Histologic analysis of full-thickness macrosections of the face and neck was performed in 73 samples from 11 fresh cadavers (six male and five female cadavers; mean age, 81 years). 27 2. Sheet plastination of the head and neck of 10 fresh cadavers were processed by von Hagens plastination in the axial, sagittal, and coronal planes using their latest technique (four male and six female cadavers; mean age, 67 years).…”

Section: Methodsmentioning

confidence: 99%

The Deep Fascia of the Head and Neck Revisited: Relationship with the Facial Nerve and Implications for Rhytidectomy

Minelli

Lei

Mendelson³

2023

Self Cite

Background: The deep fascia is important in face-lift surgery, as it is relied on for protection of the facial nerve during surgical dissection. Lack of consistency with the term may be attributable to the term deep fascia having two different meanings. It is a specific type of connective tissue, classically thin, fibrous, and flat, whereas in the description of the layers of the face and neck, the deep fascia layer includes all the connective tissue deep to the superficial fascia layer. This cadaver study was undertaken to clarify the layered anatomy of the face and neck and its relationship with the facial nerve branches. Methods: Preliminary dissections and macrosectioning, followed by a conclusive series of standardized layered dissections, histologic analysis, and sheet plastination, were performed on 50 cadaver heads. Results: The deep fascia is thin in convex areas of the face and neck, and thicker in concave areas; it is interspersed with deep fat. The facial nerve branches, after emerging from the parotid gland, are embedded within the deep fascia, not deep to it. They transition from deep within the deep fascia at specific locations to course in the most superficial part of the deep fascia where they underlie their target superficial fascia muscles and are at risk from deep plane face-lift dissection. Conclusions: The deep fascia layer is a multilamellar fibrofatty layer of variable thickness, which includes the deep fat in which the facial nerve branches are embedded. In deep plane face-lift surgery, dissection must be performed in the most superficial level of this deep fascia layer.

“…Histologic images of full-thickness macrosections were studied on 10 cadavers to investigate the microanatomy of glideplanes and ligaments. 32 In addition, the difference between a hanging cheek versus a no-release lifted cheek was studied histologically in 6 hemifaces.…”

Section: Methodsmentioning

confidence: 99%

Anatomy of the Facial Glideplanes, Deep Plane Spaces and Ligaments: Implications for Surgical and Non-Surgical Lifting Procedures

Minelli,

Brown,

van der Lei

et al. 2023

Self Cite

BACKGROUND: The soft tissue glideplanes of the face are functionally important and have a role in facial rejuvenation surgery. The aim of this study was to improve our understanding of soft tissue mobility of the face and its impact on the redraping of tissues involved in facelifting. The consequences of “no-release” and “extensive-release” lifting were analyzed to explain the difference in efficacy and potential longevity between these two contrasting philosophies. MATERIALS & METHODS: Preliminary dissections and macro sectioning were followed by a definitive series of standardized layered dissections on fifty cadaver heads, along with histology, sheet plastination, and mechanical testing. RESULTS: The previously described spaces are potential surgical dissection planes deep to the superficial fascia layer. The classically described retaining ligaments are local reinforcements of a system of small retaining fibers (retinacula cutis and deep retinacula fibers) which provide support of the soft tissues of the face and neck against gravitational sagging while allowing certain mobility. This mobility is utilized when mobile tissues are lifted without surgical release. However, the process of dragging up these fibers results in a loss of their previous, anti-gravitational, supportive orientation. CONCLUSION: No-release lifting techniques, such as thread lifts and minimal-invasive facelifts, tighten “tissue laxity” with a change of the gravity-opposing tissue architecture, placing the weight of the flap solely on the fixation, which limits longevity of the lift. The alternative, to perform a full release with redraping, enables reattachment of the flap to a higher position, with preservation of the original deep fascial architecture with its antigravity orientation and natural mobility, conceivably improving the longevity of the lift.