An Anatomical Dissection Method for Observation of Fibrous Facial Structures

Abstract

Background: In recent years, structures including the superficial musculoaponeurotic system and retaining ligaments that support the facial soft tissue have been clarified. However, these structures are very difficult to observe in their entirety by the standard gross anatomical procedure (ie, dissection from superficial to deep layers). Furthermore, accurate descriptions of these structures are rare in both anatomical and plastic surgery textbooks. The aim of this study was to clarify the facial fibrous structures in a gross anatomical view. Methods: The authors’ novel method used soft facial tissue and bone. The tissue was fixed in gelatin and sectioned at a thickness of 5 to 10 mm. Each section was placed on a wooden board; the bone was then pinned, and the skin was pulled outward with sutures to hyperextend the soft tissue. Subsequently, the loose connective tissue was torn and fat tissue was removed under a surgical microscope. After the removal of fat tissue, the fibrous facial structures (eg, the superficial musculoaponeurotic system and retaining ligaments) could be observed clearly. Results: The thickness of the sections allowed three-dimensional observation, such that a structure located deep within a section could be clearly observed. The expansion of soft tissue facilitated observation of the facial layer and fibrous structures, and the locations of nerves and vessels. Therefore, the facial layer structure was readily discerned. Conclusion: This method is likely to be very useful in the field of plastic surgery because it enabled intuitive identification of facial layers and their characteristics. Clinical Relevance Statement: The dissection method developed by the authors reveals the connected morphology of each tissue of the face, thus providing basic data for analyzing soft tissue changes due to aging and gravity. This will be useful for the development of anti-aging medicine.

A new injection method for identifying the subpopliteal recess of the knee

“…In traditional gross anatomical dissection, the three‐dimensional relationships between tissues are damaged because the superficial structures are detached or cut to expose the deep structures. It is possible to simulate the muscles and blood vessels in their entirety and show their distributions by connecting the stumps, even if they are cut (Han et al, 2023; Hashiguchi et al, 2023; Watanabe et al, 2023). However, it is difficult to confirm the continuity of the joint capsule and the bursa after they are cut because of their delicate and vague color tone.…”

“…After injection, the ECL cures quickly by resting at room temperature. Specimens stained by this method can be observed not only via traditional gross anatomical dissection, but also via cross‐sectional dissection (Han et al, 2023; Hashiguchi et al, 2023; Watanabe et al, 2023).…”

Three sublayers in the SMAS: Observations of facial soft tissue using the stretched tissue dissection method focusing on the SMAS

“…Although the superficial musculoaponeurotic system (SMAS), which corresponds to the superficial fascia of the face, is generally recognized in the field of plastic surgery, the SMAS still remains controversial in some perspectives, including the morphology of each part and the connection between tissues comprising the SMAS such as between the SMAS on the parotid gland (PG) and the superficial temporal fascia (STF). To solve these issues, we developed a new anatomical dissection method named Stretched Tissue Dissection (STD) (Hashiguchi et al, n.d.). This anatomical dissection method has the following merits: the tissue can be observed in three dimension, the area of loose connective tissue is stretched and can be identified clearly, the fibrous tissue becomes hard via formalin fixation and is clearly observed, the position of each tissue in a layer, such as facial muscles, nerves, and blood vessels, can be observed clearly, and the dynamic connection of layers can be observed because you can move the tissue using tweezers (Hashiguchi et al, n.d.).…”

“…To solve these issues, we developed a new anatomical dissection method named Stretched Tissue Dissection (STD) (Hashiguchi et al, n.d.). This anatomical dissection method has the following merits: the tissue can be observed in three dimension, the area of loose connective tissue is stretched and can be identified clearly, the fibrous tissue becomes hard via formalin fixation and is clearly observed, the position of each tissue in a layer, such as facial muscles, nerves, and blood vessels, can be observed clearly, and the dynamic connection of layers can be observed because you can move the tissue using tweezers (Hashiguchi et al, n.d.). This method allows for the observation of the layers over a wide area, filling the gap between microscopic and macroscopic observation.…”

Discussion: The Superficial Musculoaponeurotic System: Does It Really Exist as an Anatomical Entity?

“…In this conclusion, the authors seem to define the SMAS as layer 3 alone, because layer 2 obviously continues anterior to the parotid. Opposing opinions of the existence of the SMAS go as far back as Gardetto et al, 10 who, in 2003, questioned its potential presence in the midface, to Hashiguchi et al, 11 who recently identify the SMAS in almost all of their sections using a gelatin-fixation technique, including in areas anterior to the parotid.…”