Pilot Study: Endoscopic Anatomical Study of the Lower Premasseter Space and Buccal Space for Sub–superficial Musculo-aponeurotic System Face Lift: Observations Based on Live Dissections

Abstract

Background:

Sub-superficial musculo-aponeurotic system dissections of the lower premasseteric space (LPMS) and buccal space (BS) performed under direct visualization are challenging because of the close relationship between neurovascular bundles and the fascioligamentous system, making these structures prone to injury. This pilot study aims to document the endoscopic anatomy of these spaces through intraoperative visualization, enabling clearer identification and description of key structures.

Methods:

Five representative cases were selected from a series of 80 sub-superficial musculo-aponeurotic system face lift dissections for this observational, descriptive pilot study. Inclusion was based on high-quality intraoperative imaging and preservation of anatomical integrity. Endoscopic dissections were performed using a 4-mm, 30-degree endoscope. Photographic and video documentation of the LPMS and BS were obtained and reviewed qualitatively. No objective measurements or interobserver validation were performed.

Results:

Endoscopic visualization revealed the detailed anatomy of both spaces. The LPMS was identified as a rhomboidal cavity bordered by the buccinator, masseteric fascia, parotid gland, and the BS. The BS appeared as a wedge-shaped cavity containing the buccal fat pad and traversed by the facial vessels and buccal nerve branches. High-definition photographs demonstrated differentiation among ligamentous, vascular, and neural structures.

Conclusions:

Within the limitations of this pilot study, the LPMS and BS appeared to be natural optical cavities of the face that may be suitable for endoscopic exploration. Endoscopic visualization may allow precise identification of their contents and support safer release of fascial and ligamentous structures. These preliminary observations require validation through controlled comparative studies to confirm any potential reduction in neurovascular injury risk.

Takeaways

Question: Can endoscopic visualization improve the identification of anatomical structures within the lower premasseteric space and buccal space in living tissue to complement existing anatomical knowledge derived from cadaveric dissections?

Findings: In this study, 5 cases were selected from 80 face lift procedures with intraoperative endoscopic documentation. Endoscopic visualization provided magnified views of the spaces, enabling differentiation of ligamentous, vascular, and neural structures and confirming anatomical relationships previously described in cadaveric studies.

Meaning: Endoscopic visualization may help surgeons better recognize deep facial anatomy within natural spaces, potentially supporting safer sub-superficial musculo-aponeurotic system dissection during face lifts and complementing the historical anatomical knowledge derived from cadaveric dissections.

INTRODUCTION

Endoscopic techniques for facial rejuvenation have been widely developed during the past 3 decades, pioneered by Vasconez et al,¹ Isse,² Ramirez,³ and Del Campo et al.⁴ These approaches introduced the concept of minimally invasive access to facial planes, enabling surgeons to work within natural spaces of the face while reducing visible scars and recovery time.

The anatomical descriptions made by Mendelson and Nahai^5,6 enabled a safer approach to the neurovascular bundles in high-risk areas, representing an advancement over initial descriptions by Skoog,⁷ Hamra,⁸ and Stuzin et al,⁹ who presented sub-superficial musculo-aponeurotic system (SMAS) techniques primarily to improve face lift results. However, the anatomical descriptions remained difficult to interpret due to the proximity and similarity of ligaments and arteries, thereby increasing perceived surgical risk.

The anatomical contributions of Mendelson and Wong¹⁰ redefined the understanding of facial retaining ligaments and spaces. Among these, the lower premasseteric space (LPMS) and the buccal space (BS) are of clinical importance. The LPMS occupies the lower half of the masseter muscle, in front of the parotid gland, along a line connecting the upper edge of the tragus to the oral commissure, adjacent to the mandibular body.¹¹ The BS is a deep soft tissue space located anterior to the masseteric space.¹² It extends from the posterior border near the masseter to its anterior aspect, where the floor of the space (formed by the buccinator and its fat) joins its roof, formed by the facial extension of the medial cheek SMAS, and continues toward the oral commissure.¹³

Understanding the anatomy of the LPMS and BS is essential for safe and reproducible face lift dissections. In particular, accurate recognition of fascioligamentous structures and the relationship of neurovascular bundles in these areas may help minimize complications while optimizing outcomes in facial rejuvenation. Although cadaveric studies have contributed significantly to anatomical knowledge, intraoperative endoscopic visualization provides an opportunity to observe theoretical anatomy in living tissue during surgical procedures.

Study Objective

This pilot clinical study was designed as a descriptive anatomical work to illustrate and document the LPMS and BS through intraoperative endoscopic visualization in a series of representative face lift procedures. The study does not aim to validate clinical outcomes, measure complication rates, or establish the superiority of endoscopic over direct visualization. By providing high-definition images and describing anatomical landmarks observed in living tissue, the study aims to complement existing anatomical knowledge derived from cadaveric dissections.

MATERIALS AND METHODS

Study Design

This is an observational descriptive pilot study based on retrospective analysis of intraoperative documentation from face lift procedures. Between 2019 and 2023, a total of 80 consecutive patients underwent rhytidectomy procedures at a single private practice in Colombia. All procedures were performed by the same senior surgeon using sub-SMAS dissection with ligament-release techniques, with or without concurrent cervicoplasty.

Selection Criteria

Cases were selected through purposive sampling based on the following inclusion criteria: (1) availability of high-quality intraoperative photographic documentation of the dissection; (2) preservation of anatomical structures without distortion or artifact caused by surgical maneuvers; and (3) representation of consistent anatomical findings across patients, allowing correlation with established anatomical descriptions. Patients were excluded if intraoperative visualization was compromised or if key anatomical planes were not adequately exposed.

Acknowledgment of Selection Bias

This nonrandom selection introduces inherent bias and limits generalizability to the broader surgical population. The purposive selection of cases with high visual quality and preserved anatomy may not represent the full spectrum of anatomical variations or challenging surgical scenarios encountered in routine practice.

Patient Characteristics

Overall, patients did not have cardiovascular risk and were classified as ASA I or ASA II, based on history-taking and clinical evaluation. In some cases, mild controlled hypotension was used (mean arterial pressure maintained at ≥65 mm Hg). Tumescent infiltration with 1% lidocaine was administered. Additionally, 22 (27.5%) patients underwent blepharoplasty, and 20 patients underwent a forehead lift. Five patients received only a temporo-mastoid approach without a preauricular incision.

The 5 representative cases consisted of women aged between 46 and 64 years who underwent aesthetic facial rejuvenation procedures. All patients provided written informed consent for the use of intraoperative imaging and anonymized clinical data for academic and research purposes.

Surgical Approach

A 2-cm skin window was created along the canto-gonion line, approximately 25 mm anterior to the inferior border of the tragus. Through this access, sub-SMAS dissection was carried out using a 4-mm Karl Storz Hopkins Optic 30-degree endoscope, with craniocaudal progression of the surgical field up to the labiomental groove and mentonian fat pad.

The LPMS was approached first, followed by exploration of the BS. Both spaces were documented with high-definition photographs and video sequences, which were later reviewed and compared with the anatomical descriptions of Mendelson and other authors.^11,14–16

Anatomical Analysis

Anatomical structures were identified qualitatively based on morphological characteristics (color, texture, mobility, pulsation) and comparison with established anatomical descriptions. No formal measurement protocol was used. Structures were identified by a single surgeon (J.I.C.) without independent reviewer assessment or interobserver validation.

Documentation

Four representative photographs were selected from 5 live surgery videos chosen from 80 facial procedures, describing anatomical structures in each space in the progressive order of dissection. Additionally, 2 video segments were selected to show the endoscopic anatomy with accompanying commentary. The set of photographs was taken during dissections of the anatomical spaces as shown in Figure 1.

Fig. 1.

Graphical description and location of the lower premasseter space and BS. It shows the entry site on the canto-gonion diagonal. Red lines indicate the approximate locations of the photographs.

Red lines show the entry site on the canto-gonion diagonal and indicate the approximate locations of the photographs.

• Red diagonal 1: proximal to the opening of the LPMS.

• Red diagonal 2: in the middle of the LPMS.

• Red diagonal 3: distal to the LPMS and at the opening of the BS (LPMS–BS interface).

• Red diagonal 4: BS near the mentonian region (distal view).

Scope of the Study

This article does not intend to present strategies or maneuvers for surgical modification of facial anatomical structures, nor the results of a specific surgical technique. It is designed solely to illustrate and describe the clear anatomy of the LPMS and BS with the endoscope as a tool for the surgeons working in the deep facial anatomy. The study provides no comparative data, outcome measurements, or validation of clinical efficacy.

Ethical Considerations

The study was conducted in accordance with the principles of the Declaration of Helsinki. As a retrospective descriptive analysis of intraoperative documentation, it was exempt from formal institutional review board approval. Patients and the clinic were informed of the academic nature of the study and consented to the use of their data.

RESULTS

Endoscopic visualization was successfully performed in all 5 representative face lift cases. The optical approach revealed clear anatomical boundaries of both the LPMS and the BS, allowing identification of ligamentous, vascular, and neural structures based on their morphological characteristics.

Lower Premasseteric Space

The LPMS was consistently identified as a rhomboidal anatomical space with a floor formed by the extension of the parotid-masseteric fascia that covers the muscle (masseteric fascia; deep plane 5 of Mendelson).¹² The space contained nerve bundles and the ligamentous system.¹¹ The inferior buccal trunk was observed crossing diagonally toward the anterosuperior corner, where the main masseteric ligament was identified, before ascending to the lip muscles, where it emitted anastomotic branches. A row of minor masseteric ligaments was observed running parallel to the anterior edge, and the mandibular branch was seen passing through the floor space more anteriorly than the buccal trunk, or outside it at its lower edge.

Buccal Space

The BS appeared as a wedge-shaped cavity located deep to the SMAS, containing the buccal fat pad and traversed by the facial artery and vein.¹⁷ The upper half of its lateral border was formed by the medial SMAS, and the platysma formed its lower half. Medially, it was bounded by the buccinator with its fascia.¹⁴ The facial artery was observed crossing the mandibular edge anterior to the facial vein; upon reaching the modiolus, it branched into the labial and mental arteries before becoming the angular artery. The buccal and zygomatic branches of the facial nerve were seen passing through the space after crossing the facial vein. The posterior limit was occupied by the distal portion of the parotid duct.

Photographic and Video Documentation

High-definition intraoperative images showed that the endoscope provided magnified and comfortable optical access to these anatomical spaces. Photographic sequences demonstrated the layered relationship between the buccal fat pad, vascular pedicle, and nerve branches, with consistent findings across all 5 cases. Videos further illustrated these anatomical landmarks.

Important Note

The selected cases represent favorable anatomical scenarios with adequate tissue quality. The findings may not be representative of all clinical scenarios.

Endoscopic Visualization 1

A 64-year-old woman with midfacial ptosis, deep jowls, and platysmal bands underwent deep-plane cheek and neck rejuvenation surgery (Fig. 2). Live surgical anatomical dissection of both the LPMS and BS is demonstrated in Video 1, where key anatomical structures are identified (Fig. 2). (See Video 1 [online], which displays anatomical dissection 1 of the LPMS and BS.)

Fig. 2.

Endoscopic anatomy of LPMS and BS. A, Proximal view of the LPMS. B, Middle-level view of the LPMS. C, View of the entry into the upper DAO recess to expose the mandibular osseocutaneous ligament. D, View of the interface between BS and mentonian region. Original image published in Cir Plást Iberolatinoam. 2024;50:141–150 and reproduced with permission.¹⁸ DAO, depressor anguli oris.

Video 1. Lower premasseter space and buccal space series 1. The cavity is clear with well-defined upper and lower boundaries and its roof and floor. Release of the minor and major masseteric ligaments, as well as the anterior membrane of the LPMS was observed to open the BS. The release of the platysmal mesentery was observed until it reached the middle premasseter space. Dissection extended to the mandibular osseocutaneous ligament to observe its release, the Mentonian fat pad, the jowl, and the lower lip depressor as the cephalic limits of the BS. Classic anatomy is evident, where neurovascular bundles cannot be visualized when passing through the roof (sub-SMAS).

Download video file ^{(92.5MB, mp4)}

Endoscopic Visualization 2

A 46-year-old woman with midfacial ptosis, deep cheek folds, and platysmal bands underwent deep-plane face lift surgery for cheek and neck rejuvenation, an endoscopic forehead lift, and blepharoplasty (Fig. 3). Live surgical anatomical dissection of both the LPMS and BS is demonstrated in Video 2, where key anatomical structures are identified (Fig. 3). (See Video 2 [online], which displays anatomical dissection 2 of the LPMS and BS.)

Fig. 3.

Endoscopic anatomy of LPMS and BS. A, Proximal dissection of the LPMS near the middle premasseter space. B, Middle-level view of the 2 premasseteric spaces, highlighting the upper and key masseteric ligament with its tree-like shape. The buccal trunk is observed in the floor. C, Distal view of the LPMS and the BS. D, Opening of the DAO recess to identify the mandibular osseocutaneous ligament, comprising a single tree-like branch. Original image published in Cir Plást Iberolatinoam. 2024;50:141–150 and reproduced with permission.¹⁸ DAO, depressor anguli oris.

Video 2. Lower premasseter space and buccal space series 2. The classic anatomy is visualized, showing a large masseteric cavity with all its boundaries, minor and main masseteric ligaments, and an intercommunicating buccal nerve. Precise and safe electrocoagulation of platysma without causing injuries is shown. The BS is observed with the branch of the buccal nerve over the modiolus, as well as the release of the middle premasseter space in its lower portion, visualizing the upper masseteric ligament near the buccal trunk and the Bichat's bag with the buccal nerve branches in its capsule. The mandibular osseocutaneous ligament and the mandibular cutaneous ligament were defined, and their release was observed.

Download video file ^{(52.2MB, mp4)}

Endoscopic Visualization 3

A 57-year-old woman with midfacial ptosis, deep cheek folds, and platysmal bands underwent deep-plane face lift surgery for cheek and neck rejuvenation (Fig. 4).

Fig. 4.

Endoscopic anatomy of LPMS and BS. A, Proximal view of the LPMS in a compartment with abundant fat. B, Middle-level view of the premassteric space and its 2 compartments. C, Endoscopic view of the BS. D, Zoom-in endoscopic view of the mandibular osseocutaneous ligament showing 2 key branches. The images in parts C and D were originally published in Cir Plást Iberolatinoam. 2024;50:141–150 and are reproduced with permission.¹⁸

Endoscopic Visualization 4

A 62-year-old woman with early relapse (after 1 y) of a previous face lift performed by another surgeon (Fig. 5). High-definition ultrasound revealed severe allogenosis, and deep-plane surgery was recommended.

Fig. 5.

Endoscopic anatomy of LPMS and BS. Patient with silicone-type alloplastic degeneration. A detailed view of the mandibular osseocutaneous ligament before its release. Original image published in Cir Plást Iberolatinoam. 2024;50:141-150 and reproduced with permission.¹⁸

Endoscopic Visualization 5

A 59-year-old woman with midfacial ptosis, deep jowls, and platysmal bands underwent deep-plane cheek and neck rejuvenation surgery (Fig. 6).

Fig. 6.

Endoscopic anatomy of LPMS and BS. A, Proximal view of the LPMS highlighting the lower buccal trunk passing through. B, Middle-level view of the space showing the key masseteric ligament being crossed by the buccal nerve at the LPMS–BS interface. C, Middle-level view of the space showing the key masseteric ligament being released, with the opening of the middle premasseteric space and the BS. D, Middle-level view highlighting the mandibular nerve crossing the facial artery.

Clinical Observations

No intraoperative complications related to the use of the endoscope were observed. Dissections proceeded without an apparent increase in operative time. The additional optical access facilitated the release of the mandibular and masseteric ligaments. Patients tolerated the procedures well, and the incorporation of endoscopic visualization did not alter postoperative recovery. However, these observations are limited to 5 selected cases and cannot be generalized.

DISCUSSION

Established Anatomical Framework

The LPMS holds clinical importance because its structural changes contribute to the development of jowls as part of facial aging.¹² In young individuals, ligaments are firm and supported by fasciomembranous and platysmal structures that are tightly attached to the masseter. With aging, these supports weaken, the space distends, and jowls form progressively. Reece et al¹⁵ described that the superior and inferior jowl cushions descend below the mandibular cutaneous ligament, with the lower edge of the LPMS extending inferiorly to create the labiomental groove, anchored by the mandibular osseocutaneous ligament.

Anatomically, the roof of the LPMS consists of the platysma with its fascia and fat,¹⁶ merging posteriorly with the parotid-auricular fascia. The upper border is defined by platysmal insertions into the masseter, which extend to the modiolus. Together with the middle space, these reflections form a mesentery-like configuration. The anterior border is a thin membranous extension parallel to the masseter’s anterior edge, whereas the inferior border lies approximately 15 mm above the gonion, forming the platysma–mandibular adhesion. This continues about 25 mm anterior to the palpable masseter border, where the mandibular cutaneous ligament originates.¹²

The BS, primarily containing the buccal fat pad, facilitates movement of the nasolabial midface segment and cushions the region during jaw opening. The posterior limit is the masseteric fascia, which encloses the facial vein. The anterior limit is formed by the modiolus pillar and the muscles inserting into it, including the levator anguli oris, zygomaticus major and minor, risorius, depressor anguli oris, and platysma.¹⁴ The inferior limit corresponds to the platysma’s mandibular insertion and the mandibular ligament, whereas the superior border is defined by fascial extensions of the zygomaticus major muscle and the buccinator’s bony origin.¹⁴

With aging, laxity of the lower masseteric ligaments allows the BS to enlarge, leading to downward prolapse of the buccal fat pad below the oral commissure. When this pad extends to cover the anterior border of the lower masseter, it accentuates the labiomental sulcus and jowl formation.¹⁷

Observations From the Present Study

In our pilot series, the LPMS and BS were visualized endoscopically in all 5 selected cases. The anatomical structures identified corresponded to those described by Mendelson and other authors in cadaveric studies.^{11,14–16,19} The endoscope provided magnified views of these spaces, allowing visual differentiation of structures based on their morphological characteristics, some of which are shown in Table 1.

Table 1.

Morphological Characteristics for Structure Differentiation

Feature	Nerves	Ligaments	Arteries	Veins
Color	Pearl white	White-beige	Grayish white	Pink/red
Texture/appearance	Smooth, cylindrical, trunks	Fibrous, firm, tree-like	Smooth, tubular, cables	Smooth, tubular
Mobility	Mobile, elastic	Fixed at insertions	Mobile	Mobile
Trajectory	Horizontal and vertical (deep fascia to SMAS)	Vertical	Horizontal and vertical	Horizontal and vertical
Pulsation	Absent	Absent	Present	Absent

These characteristics represent observational impressions of the operating surgeon and have not been validated through controlled comparison or interobserver assessment.

Contribution of This Work

The anatomical structures visualized in this study have been well described by Mendelson and other authors through cadaveric dissection.^{11,14–16,19} The contribution of the present work is the documentation of these structures through intraoperative endoscopic visualization, demonstrating their appearance in living tissue during actual surgical procedures. This study does not claim to identify previously unknown structures, but rather to illustrate the feasibility of endoscopic visualization as a complementary approach to anatomical documentation in facial surgery.

Theoretical Advantages of Endoscopic Visualization

The LPMS and BS seemed to be suitable for endoscopic visualization because they are naturally distensible, unlike other facial spaces where surgical creation is required. Endoscopy has demonstrated its value in the upper face for decades in procedures such as the extended brow lift,²⁰ endoscopic brow lift and midface lift,²¹ the endoscopic forehead lift,²² and others. Applying the same principle to the LPMS and BS may provide direct optical access to structures that are otherwise difficult to visualize.

Traditional descriptions of the deep face emphasize the close relationship and similarity between ligaments, nerves, vessels, and arterial bundles, which increases perceived surgical risk.¹⁹ Endoscopic visualization may allow better differentiation of these structures (Table 1), potentially reducing uncertainty and improving surgical safety. However, this potential advantage has not been validated in the present study and would require comparative studies with complication rate analysis to confirm. The videos and photographs presented in this study demonstrate live anatomical relationships that have previously been described only in cadaveric dissections or schematic diagrams.

Another theoretical advantage of endoscopy is its adaptability to individual anatomical variation. Unlike rigid measurements derived from cadaveric studies, intraoperative visualization may account for patient-specific variability, avoiding the limitations of average-based anatomical schemas. This flexibility may be relevant in aging patients, in whom structural changes alter relationships described in younger or cadaveric specimens. A comparison between visualization methods based on observational impressions is outlined in Table 2.

Table 2.

Comparison of Visualization Methods: Observational Impressions.

Feature	Direct Visualization	Endoscopic Visualization
Magnification	Limited (1–3× with loupes)	10–20× magnified view
Illumination	Variable; shadows possible	Coaxial and uniform
Access to deep cavities	Requires wider exposure	Through a small window
Depth perception	Three-dimensional	Two-dimensional image
Equipment required	Standard instruments	Endoscopic system
Learning curve	Standard surgical training	Significant
Anatomical structures of the BS (1–4)	+	++++
Nerve migration from the deep fascia to the superficial fascia (1–4)	+	++++

This comparison represents subjective observations by the operating surgeon and has not been validated through controlled comparison or blinded assessment. The relative advantages listed are theoretical and require prospective validation.

Endoscopic access to the zygomatic, masseteric, and mandibular ligaments, as well as to the BS and its mesenteries, enables surgeons to release these structures under direct vision. Although BS dissection has been considered high risk, endoscopy may mitigate the risk of injury by providing a magnified view of the space and its contents, including the platysma–mandibular ligament and the mandibular osseocutaneous ligament.¹⁸

Limitations

This study has significant limitations that must be considered when interpreting its findings:

1. Selection bias: Cases were selected through purposive sampling for optimal visualization quality, which does not represent the full spectrum of anatomical variations or surgical scenarios encountered in routine practice.

2. Single-surgeon observation: All observations were made by a single experienced surgeon without independent reviewer assessment or interobserver validation.

3. Absence of objective measurements: The study is based on qualitative visual observation without anatomical measurements, variability analysis, or reproducibility assessment.

4. No comparative control: The study provides no comparison with direct visualization and cannot establish superiority of 1 method over another.

5. No outcome data: The study provides no evidence of reduced neurovascular injury rates or improved clinical outcomes. Claims regarding improved safety are theoretical and extrapolated from the optical characteristics observed.

6. Limited generalizability: The findings may not be applicable to patients with prior facial surgery, significant scarring, unusual anatomical variants, or complex revision cases.

7. Equipment and training requirements: The technique requires specific endoscopic equipment, which may not be available in all surgical settings. A significant learning curve is required to develop proficiency in coordinating endoscopic visualization with surgical dissection. Widespread adoption would require structured training programs.

8. Small sample size: The limited sample of 5 selected cases restricts generalizability.

Future studies should incorporate larger cohorts with random or consecutive case selection, standardized measurements, blinded interobserver assessment, comparative design (endoscopic versus direct visualization), and objective outcome measures.

CONCLUSIONS

Within the significant limitations of this pilot study, including single-surgeon observation and the absence of quantitative measurements, we present preliminary observations suggesting that the LPMS and BS may serve as natural optical cavities suitable for endoscopic visualization in sub-SMAS facial surgery.

Endoscopic visualization allowed identification and documentation of anatomical structures within these spaces, corresponding to established cadaveric descriptions. The magnified view may facilitate differentiation between ligamentous, vascular, and neural structures based on morphological characteristics, potentially reducing specific risks.

These observations should be interpreted as hypothesis-generating rather than definitive. The theoretical potential for improved anatomical recognition and safer surgical dissection requires validation through larger, controlled studies with objective outcome measures.

The primary applicability of these findings may be in minimal-access surgical approaches, though the requirement for specialized equipment and training may limit widespread adoption.

DISCLOSURE

The author has no financial interest to declare in relation to the content of this article.